Splash - A javascript rendering service¶

Splash is a javascript rendering service. It’s a lightweight web browser with an HTTP API, implemented in Python using Twisted and QT. The (twisted) QT reactor is used to make the sever fully asynchronous allowing to take advantage of webkit concurrency via QT main loop. Some of Splash features:

process multiple webpages in parallel;
get HTML results and/or take screenshots;
turn OFF images or use Adblock Plus rules to make rendering faster;
execute custom JavaScript in page context;
write Lua browsing scripts;
develop Splash Lua scripts in Splash-Jupyter Notebooks.
get detailed rendering info in HAR format.

Documentation¶

Installation¶

Linux + Docker¶

Install Docker.
Pull the image:
```
$ sudo docker pull scrapinghub/splash
```

Start the container:

$ sudo docker run -p 5023:5023 -p 8050:8050 -p 8051:8051 scrapinghub/splash

Splash is now available at 0.0.0.0 at ports 8050 (http), 8051 (https) and 5023 (telnet).

OS X + Docker¶

Install Docker (via Boot2Docker).
Pull the image:
```
$ docker pull scrapinghub/splash
```

Start the container:

$ docker run -p 5023:5023 -p 8050:8050 -p 8051:8051 scrapinghub/splash

Figure out the ip address of boot2docker:

$ boot2docker ip

The VM's Host only interface IP address is: 192.168.59.103

Splash is available at the returned IP address at ports 8050 (http), 8051 (https) and 5023 (telnet).

Ubuntu 14.04 (manual way)¶

1. Install system dependencies (check provision.sh <https://github.com/scrapinghub/splash/blob/master/dockerfiles/splash/provision.sh>)

Clone the repo from Github:

$ git clone https://github.com/scrapinghub/splash/

Install dependencies with pip:

$ cd splash
$ pip3 install -r requirements.txt

To run the server execute the following command:

python3 -m splash.server

Run python -m splash.server --help to see options available.

By default, Splash API endpoints listen to port 8050 on all available IPv4 addresses. To change the port use --port option:

python3 -m splash.server --port=5000

Required Python packages¶

# install PyQt5 (Splash is tested on PyQT 5.5.1)
# and the following packages:
twisted >= 15.5.0
qt5reactor
psutil
adblockparser >= 0.4
https://github.com/sunu/pyre2/archive/c610be52c3b5379b257d56fc0669d022fd70082a.zip#egg=re2
xvfbwrapper
Pillow
six

# for scripting support
cython
https://github.com/scoder/lupa/archive/8c74d0a278b45df5d813abbab64377e80864bd56.zip#egg=lupa --install-option="--with-cython"
funcparserlib >= 0.3.6

Splash Versions¶

docker pull scrapinghub/splash will give you the latest stable Splash release. To obtain the latest development version use docker pull scrapinghub/splash:master. Specific Splash versions are also available, e.g. docker pull scrapinghub/splash:1.8.

Customizing Dockerized Splash¶

Passing Custom Options¶

To run Splash with custom options pass them to docker run. For example, let’s increase log verbosity:

$ docker run -p 8050:8050 scrapinghub/splash -v3

To see all possible options pass --help. Not all options will work the same inside Docker: changing ports doesn’t make sense (use docker run options instead), and paths are paths in the container.

Building Local Docker Images¶

To build your own Docker image, checkout Splash source code using git, then execute the following command from Splash source root:

$ docker build -t my-local-splash .

To build Splash-Jupyter Docker image use this command:

$ docker build -t my-local-splash-jupyter -f  dockerfiles/splash-jupyter/Dockerfile .

You may have to change FROM line in dockerfiles/splash-jupyter/Dockerfile if you want it to be based on your local Splash Docker container.

Splash HTTP API¶

Consult with Installation to get Splash up and running.

Splash is controlled via HTTP API. For all endpoints below parameters may be sent either as GET arguments or encoded to JSON and POSTed with Content-Type: application/json header.

The most versatile endpoint that provides all Splash features is execute (WARNING: it is still experimental). Other endpoints may be easier to use in specific cases - for example, render.png returns a screenshot in PNG format that can be used as img src without any further processing, and render.json is convenient if you don’t need to interact with a page.

The following endpoints are supported:

render.html¶

Return the HTML of the javascript-rendered page.

Arguments:

url : string : required: The url to render (required)

baseurl : string : optional

The base url to render the page with.

If given, base HTML content will be feched from the URL given in the url argument, and render using this as the base url.

timeout : float : optional

A timeout (in seconds) for the render (defaults to 30).

By default, maximum allowed value for the timeout is 60 seconds. To override it start Splash with --max-timeout command line option. For example, here Splash is configured to allow timeouts up to 2 minutes:

$ python -m splash.server --max-timeout 120

resource_timeout : float : optional

A timeout (in seconds) for individual network requests.

See also: splash:on_request and its request:set_timeout(timeout) method; splash.resource_timeout attribute.

wait : float : optional: Time (in seconds) to wait for updates after page is loaded (defaults to 0). Increase this value if you expect pages to contain setInterval/setTimeout javascript calls, because with wait=0 callbacks of setInterval/setTimeout won’t be executed. Non-zero wait is also required for PNG and JPEG rendering when doing full-page rendering (see render_all). Maximum allowed value for wait is 10 seconds.

proxy : string : optional

Proxy profile name or proxy URL. See Proxy Profiles.

A proxy URL should have the following format: [protocol://][user:password@]proxyhost[:port])

Where protocol is either http or socks5. If port is not specified, the port 1080 is used by default.

js : string : optional: Javascript profile name. See Javascript Profiles.

js_source : string : optional: JavaScript code to be executed in page context. See Executing custom Javascript code within page context.

filters : string : optional: Comma-separated list of request filter names. See Request Filters

allowed_domains : string : optional: Comma-separated list of allowed domain names. If present, Splash won’t load anything neither from domains not in this list nor from subdomains of domains not in this list.

allowed_content_types : string : optional: Comma-separated list of allowed content types. If present, Splash will abort any request if the response’s content type doesn’t match any of the content types in this list. Wildcards are supported using the fnmatch syntax.

forbidden_content_types : string : optional: Comma-separated list of forbidden content types. If present, Splash will abort any request if the response’s content type matches any of the content types in this list. Wildcards are supported using the fnmatch syntax.

viewport : string : optional

View width and height (in pixels) of the browser viewport to render the web page. Format is “<width>x<height>”, e.g. 800x600. Default value is 1024x768.

‘viewport’ parameter is more important for PNG and JPEG rendering; it is supported for all rendering endpoints because javascript code execution can depend on viewport size.

For backward compatibility reasons, it also accepts ‘full’ as value; viewport=full is semantically equivalent to render_all=1 (see render_all).

images : integer : optional

Whether to download images. Possible values are 1 (download images) and 0 (don’t download images). Default is 1.

Note that cached images may be displayed even if this parameter is 0. You can also use Request Filters to strip unwanted contents based on URL.

headers : JSON array or object : optional

HTTP headers to set for the first outgoing request.

This option is only supported for application/json POST requests. Value could be either a JSON array with (header_name, header_value) pairs or a JSON object with header names as keys and header values as values.

“User-Agent” header is special: is is used for all outgoing requests, unlike other headers.

body : string : optional: Body of HTTP POST request to be sent if method is POST. Default content-type header for POST requests is application/x-www-form-urlencoded.

http_method : string : optional: HTTP method of outgoing Splash request. Default method is GET. Splash also supports POST.

Examples¶

Curl example:

curl 'http://localhost:8050/render.html?url=http://domain.com/page-with-javascript.html&timeout=10&wait=0.5'

The result is always encoded to utf-8. Always decode HTML data returned by render.html endpoint from utf-8 even if there are tags like

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

in the result.

render.png¶

Return a image (in PNG format) of the javascript-rendered page.

Arguments:

Same as render.html plus the following ones:

width : integer : optional: Resize the rendered image to the given width (in pixels) keeping the aspect ratio.

height : integer : optional: Crop the renderd image to the given height (in pixels). Often used in conjunction with the width argument to generate fixed-size thumbnails.

render_all : int : optional: Possible values are 1 and 0. When render_all=1, extend the viewport to include the whole webpage (possibly very tall) before rendering. Default is render_all=0.

Note

render_all=1 requires non-zero wait parameter. This is an unfortunate restriction, but it seems that this is the only way to make rendering work reliably with render_all=1.

scale_method : string : optional: Possible values are raster (default) and vector. If scale_method=raster, rescaling operation performed via width parameter is pixel-wise. If scale_method=vector, rescaling is done element-wise during rendering.

Note

Vector-based rescaling is more performant and results in crisper fonts and sharper element boundaries, however there may be rendering issues, so use it with caution.

Examples¶

Curl examples:

# render with timeout
curl 'http://localhost:8050/render.png?url=http://domain.com/page-with-javascript.html&timeout=10'

# 320x240 thumbnail
curl 'http://localhost:8050/render.png?url=http://domain.com/page-with-javascript.html&width=320&height=240'

render.jpeg¶

Return a image (in JPEG format) of the javascript-rendered page.

Arguments:

Same as render.png plus the following ones:

quality : integer : optional: JPEG quality parameter in range from 0 to 100. Default is quality=75.

Note

quality values above 95 should be avoided; quality=100 disables portions of the JPEG compression algorithm, and results in large files with hardly any gain in image quality.

Examples¶

Curl examples:

# render with default quality
curl 'http://localhost:8050/render.jpeg?url=http://domain.com/'

# render with low quality
curl 'http://localhost:8050/render.jpeg?url=http://domain.com/&quality=30'

render.har¶

Return information about Splash interaction with a website in HAR format. It includes information about requests made, responses received, timings, headers, etc.

You can use online HAR viewer to visualize information returned from this endpoint; it will be very similar to “Network” tabs in Firefox and Chrome developer tools.

Currently this endpoint doesn’t expose raw request and response contents; only meta-information like headers and timings is available.

Arguments for this endpoint are the same as for render.html.

render.json¶

Return a json-encoded dictionary with information about javascript-rendered webpage. It can include HTML, PNG and other information, based on arguments passed.

Arguments:

Same as render.jpeg plus the following ones:

html : integer : optional: Whether to include HTML in output. Possible values are 1 (include) and 0 (exclude). Default is 0.

png : integer : optional: Whether to include PNG in output. Possible values are 1 (include) and 0 (exclude). Default is 0.

jpeg : integer : optional: Whether to include JPEG in output. Possible values are 1 (include) and 0 (exclude). Default is 0.

iframes : integer : optional: Whether to include information about child frames in output. Possible values are 1 (include) and 0 (exclude). Default is 0.

script : integer : optional: Whether to include the result of the executed javascript final statement in output (see Executing custom Javascript code within page context). Possible values are 1 (include) and 0 (exclude). Default is 0.

console : integer : optional: Whether to include the executed javascript console messages in output. Possible values are 1 (include) and 0 (exclude). Default is 0.

history : integer : optional

Whether to include the history of requests/responses for webpage main frame. Possible values are 1 (include) and 0 (exclude). Default is 0.

Use it to get HTTP status codes and headers. Only information about “main” requests/responses is returned (i.e. information about related resources like images and AJAX queries is not returned). To get information about all requests and responses use ‘har’ argument.

har : integer : optional: Whether to include HAR in output. Possible values are 1 (include) and 0 (exclude). Default is 0. If this option is ON the result will contain the same data as render.har provides under ‘har’ key.

Examples¶

By default, URL, requested URL, page title and frame geometry is returned:

{
    "url": "http://crawlera.com/",
    "geometry": [0, 0, 640, 480],
    "requestedUrl": "http://crawlera.com/",
    "title": "Crawlera"
}

Add ‘html=1’ to request to add HTML to the result:

{
    "url": "http://crawlera.com/",
    "geometry": [0, 0, 640, 480],
    "requestedUrl": "http://crawlera.com/",
    "html": "<!DOCTYPE html><!--[if IE 8]>....",
    "title": "Crawlera"
}

Add ‘png=1’ to request to add base64-encoded PNG screenshot to the result:

{
    "url": "http://crawlera.com/",
    "geometry": [0, 0, 640, 480],
    "requestedUrl": "http://crawlera.com/",
    "png": "iVBORw0KGgoAAAAN...",
    "title": "Crawlera"
}

Setting both ‘html=1’ and ‘png=1’ allows to get HTML and a screenshot at the same time - this guarantees that the screenshot matches the HTML.

By adding “iframes=1” information about iframes could be obtained:

{
    "geometry": [0, 0, 640, 480],
    "frameName": "",
    "title": "Scrapinghub | Autoscraping",
    "url": "http://scrapinghub.com/autoscraping.html",
    "childFrames": [
        {
            "title": "Tutorial: Scrapinghub's autoscraping tool - YouTube",
            "url": "",
            "geometry": [235, 502, 497, 310],
            "frameName": "<!--framePath //<!--frame0-->-->",
            "requestedUrl": "http://www.youtube.com/embed/lSJvVqDLOOs?version=3&rel=1&fs=1&showsearch=0&showinfo=1&iv_load_policy=1&wmode=transparent",
            "childFrames": []
        }
    ],
    "requestedUrl": "http://scrapinghub.com/autoscraping.html"
}

Note that iframes can be nested.

Pass both ‘html=1’ and ‘iframes=1’ to get HTML for all iframes as well as for the main page:

 {
    "geometry": [0, 0, 640, 480],
    "frameName": "",
    "html": "<!DOCTYPE html...",
    "title": "Scrapinghub | Autoscraping",
    "url": "http://scrapinghub.com/autoscraping.html",
    "childFrames": [
        {
            "title": "Tutorial: Scrapinghub's autoscraping tool - YouTube",
            "url": "",
            "html": "<!DOCTYPE html>...",
            "geometry": [235, 502, 497, 310],
            "frameName": "<!--framePath //<!--frame0-->-->",
            "requestedUrl": "http://www.youtube.com/embed/lSJvVqDLOOs?version=3&rel=1&fs=1&showsearch=0&showinfo=1&iv_load_policy=1&wmode=transparent",
            "childFrames": []
        }
    ],
    "requestedUrl": "http://scrapinghub.com/autoscraping.html"
}

Unlike ‘html=1’, ‘png=1’ does not affect data in childFrames.

When executing JavaScript code (see Executing custom Javascript code within page context) add the parameter ‘script=1’ to the request to include the code output in the result:

{
    "url": "http://crawlera.com/",
    "geometry": [0, 0, 640, 480],
    "requestedUrl": "http://crawlera.com/",
    "title": "Crawlera",
    "script": "result of script..."
}

The JavaScript code supports the console.log() function to log messages. Add ‘console=1’ to the request to include the console output in the result:

{
    "url": "http://crawlera.com/",
    "geometry": [0, 0, 640, 480],
    "requestedUrl": "http://crawlera.com/",
    "title": "Crawlera",
    "script": "result of script...",
    "console": ["first log message", "second log message", ...]
}

Curl examples:

# full information
curl 'http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&png=1&html=1&iframes=1'

# HTML and meta information of page itself and all its iframes
curl 'http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&html=1&iframes=1'

# only meta information (like page/iframes titles and urls)
curl 'http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&iframes=1'

# render html and 320x240 thumbnail at once; do not return info about iframes
curl 'http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&html=1&png=1&width=320&height=240'

# Render page and execute simple Javascript function, display the js output
curl -X POST -H 'content-type: application/javascript' \
    -d 'function getAd(x){ return x; } getAd("abc");' \
    'http://localhost:8050/render.json?url=http://domain.com&script=1'

# Render page and execute simple Javascript function, display the js output and the console output
curl -X POST -H 'content-type: application/javascript' \
    -d 'function getAd(x){ return x; }; console.log("some log"); console.log("another log"); getAd("abc");' \
    'http://localhost:8050/render.json?url=http://domain.com&script=1&console=1'

execute¶

Warning

This endpoint is experimental. API could change in future releases.

Execute a custom rendering script and return a result.

render.html, render.png, render.jpeg, render.har and render.json endpoints cover many common use cases, but sometimes they are not enough. This endpoint allows to write custom Splash Scripts.

Arguments:

lua_source : string : required: Browser automation script. See Splash Scripts Tutorial for more info.

timeout : float : optional: Same as ‘timeout’ argument for render.html.
allowed_domains : string : optional: Same as ‘allowed_domains’ argument for render.html.
proxy : string : optional: Same as ‘proxy’ argument for render.html.
filters : string : optional: Same as ‘filters’ argument for render.html.

Executing custom Javascript code within page context¶

Note

Splash supports executing JavaScript code within the context of the page. The JavaScript code is executed after the page finished loading (including any delay defined by ‘wait’) but before the page is rendered. This allow to use the javascript code to modify the page being rendered.

To execute JavaScript code use js_source parameter. It should contain JavaScript code to be executed.

Note that browsers and proxies limit the amount of data can be sent using GET, so it is a good idea to use content-type: application/json POST request.

Curl example:

# Render page and modify its title dynamically
curl -X POST -H 'content-type: application/json' \
    -d '{"js_source": "document.title=\"My Title\";", "url": "http://example.com"}' \
    'http://localhost:8050/render.html'

Another way to do it is to use a POST request with the content-type set to ‘application/javascript’. The body of the request should contain the code to be executed.

Curl example:

# Render page and modify its title dynamically
curl -X POST -H 'content-type: application/javascript' \
    -d 'document.title="My Title";' \
    'http://localhost:8050/render.html?url=http://domain.com'

To get the result of a javascript function executed within page context use render.json endpoint with script = 1 parameter.

Javascript Profiles¶

Splash supports “javascript profiles” that allows to preload javascript files. Javascript files defined in a profile are executed after the page is loaded and before any javascript code defined in the request.

The preloaded files can be used in the user’s POST’ed code.

To enable javascript profiles support, run splash server with the --js-profiles-path=<path to a folder with js profiles> option:

python -m splash.server --js-profiles-path=/etc/splash/js-profiles

Note

Javascript Security¶

If Splash is started with --js-cross-domain-access option

python -m splash.server --js-cross-domain-access

then javascript code is allowed to access the content of iframes loaded from a security origin diferent to the original page (browsers usually disallow that). This feature is useful for scraping, e.g. to extract the html of a iframe page. An example of its usage:

curl -X POST -H 'content-type: application/javascript' \
    -d 'function getContents(){ var f = document.getElementById("external"); return f.contentDocument.getElementsByTagName("body")[0].innerHTML; }; getContents();' \
    'http://localhost:8050/render.html?url=http://domain.com'

The javascript function ‘getContents’ will look for a iframe with the id ‘external’ and extract its html contents.

Note that allowing cross origin javascript calls is a potential security issue, since it is possible that secret information (i.e cookies) is exposed when this support is enabled; also, some websites don’t load when cross-domain security is disabled, so this feature is OFF by default.

Request Filters¶

Splash supports filtering requests based on Adblock Plus rules. You can use filters from EasyList to remove ads and tracking codes (and thus speedup page loading), and/or write filters manually to block some of the requests (e.g. to prevent rendering of images, mp3 files, custom fonts, etc.)

To activate request filtering support start splash with --filters-path option:

python -m splash.server --filters-path=/etc/splash/filters

Note

Proxy Profiles¶

Splash supports “proxy profiles” that allows to set proxy handling rules per-request using proxy parameter.

To enable proxy profiles support, run splash server with --proxy-profiles-path=<path to a folder with proxy profiles> option:

python -m splash.server --proxy-profiles-path=/etc/splash/proxy-profiles

Note

If you run Splash using Docker, check Folders Sharing.

Then create an INI file with “proxy profile” config inside the specified folder, e.g. /etc/splash/proxy-profiles/mywebsite.ini. Example contents of this file:

[proxy]

; required
host=proxy.crawlera.com
port=8010

; optional, default is no auth
username=username
password=password

; optional, default is HTTP. Allowed values are HTTP and SOCKS5
type=HTTP

[rules]
; optional, default ".*"
whitelist=
    .*mywebsite\.com.*

; optional, default is no blacklist
blacklist=
    .*\.js.*
    .*\.css.*
    .*\.png

whitelist and blacklist are newline-separated lists of regexes. If URL matches one of whitelist patterns and matches none of blacklist patterns, proxy specified in [proxy] section is used; no proxy is used otherwise.

Then, to apply proxy rules according to this profile, add proxy=mywebsite parameter to request:

curl 'http://localhost:8050/render.html?url=http://mywebsite.com/page-with-javascript.html&proxy=mywebsite'

If default.ini profile is present, it will be used when proxy argument is not specified. If you have default.ini profile but don’t want to apply it pass none as proxy value.

Other Endpoints¶

_gc¶

To reclaim some RAM send a POST request to the /_gc endpoint:

curl -X POST http://localhost:8050/_gc

It runs the Python garbage collector and clears internal WebKit caches.

_debug¶

To get debug information about Splash instance (max RSS used, number of used file descriptors, active requests, request queue length, counts of alive objects) send a GET request to the /_debug endpoint:

curl http://localhost:8050/_debug

_ping¶

To ping Splash instance send a GET request to the /_ping endpoint:

curl http://localhost:8050/_ping

It returns “ok” status and max RSS used, if instance is alive.

Splash Scripts Tutorial¶

Warning

Scripting support is an experimental feature for early adopters; API could change in future releases.

Intro¶

Splash can execute custom rendering scripts written in the Lua programming language. This allows us to use Splash as a browser automation tool similar to PhantomJS.

To execute a script and get the result back send it to the execute endpoint in a lua_source argument.

Note

Most likely you’ll be able to follow Splash scripting examples even without knowing Lua; nevertheless, the language is worth learning. With Lua you can, for example, write Redis, Nginx, Apache, World of Warcraft scripts, create mobile apps using Moai or Corona SDK or use the state of the art Deep Learning framework Torch7. It is easy to get started and there are good online resources available like the tutorial Learn Lua in 15 minutes and the book Programming in Lua.

Let’s start with a basic example:

function main(splash)
    splash:go("http://example.com")
    splash:wait(0.5)
    local title = splash:evaljs("document.title")
    return {title=title}
end

If we submit this script to the execute endpoint in a lua_source argument, Splash will go to the example.com website, wait until it loads, wait aother half-second, then get the page title (by evaluating a JavaScript snippet in page context), and then return the result as a JSON encoded object.

Note

Splash UI provides an easy way to try scripts: there is a code editor for Lua and a button to submit a script to execute. Visit http://127.0.0.1:8050/ (or whatever host/port Splash is listening to).

Entry Point: the “main” Function¶

The script must provide a “main” function which is called by Splash. The result is returned as an HTTP response. The script could contain other helper functions and statements, but ‘main’ is required.

In the first example ‘main’ function returned a Lua table (an associative array similar to JavaScript Object or Python dict). Such results are returned as JSON.

The following will return the string {"hello":"world!"} as an HTTP response:

function main(splash)
    return {hello="world!"}
end

The script can also return a string:

function main(splash)
    return 'hello'
end

Strings are returned as-is (unlike tables they are not encoded to JSON). Let’s check it with curl:

$ curl 'http://127.0.0.1:8050/execute?lua_source=function+main%28splash%29%0D%0A++return+%27hello%27%0D%0Aend'
hello

The “main” function receives an object that allows us to control the “browser tab”. All Splash features are exposed using this object. By convention, this argument is called “splash”, but you are not required to follow this convention:

function main(please)
    please:go("http://example.com")
    please:wait(0.5)
    return "ok"
end

Where Are My Callbacks?¶

Here is a snippet from our first example:

splash:go("http://example.com")
splash:wait(0.5)
local title = splash:evaljs("document.title")

The code looks like standard procedural code; there are no callbacks or fancy control-flow structures. It doesn’t mean Splash works in a synchronous way; under the hood it is still async. When you call splash.wait(0.5), Splash switches from the script to other tasks, and comes back after 0.5s.

It is possible to use loops, conditional statements, functions as usual in Splash scripts which enables more straightforward coding.

Let’s check an example PhantomJS script:

var users = ["PhantomJS", "ariyahidayat", /*...*/];

function followers(user, callback) {
    var page = require('webpage').create();
    page.open('http://mobile.twitter.com/' + user, function (status) {
        if (status === 'fail') {
            console.log(user + ': ?');
        } else {
            var data = page.evaluate(function () {
                return document.querySelector('div.profile td.stat.stat-last div.statnum').innerText;
            });
            console.log(user + ': ' + data);
        }
        page.close();
        callback.apply();
    });
}
function process() {
    if (users.length > 0) {
        var user = users[0];
        users.splice(0, 1);
        followers(user, process);
    } else {
        phantom.exit();
    }
}
process();

The code is (arguably) tricky: process function implements a loop by creating a chain of callbacks; followers function doesn’t return a value (it would be more complex to implement) - the result is logged to the console instead.

A similar Splash script:

-- Implementation of "follow.js" example from
-- PhantomJS
-- https://github.com/ariya/phantomjs/blob/master/examples/follow.js

USERS = {
  'PhantomJS',
  'ariyahidayat',
  'detronizator',
  'KDABQt',
  'lfranchi',
  'jonleighton',
  '_jamesmgreene',
  'Vitalliumm',
}

local base = 'http://mobile.twitter.com/'
function follow(splash, user)
  local ok, msg = splash:go(base .. user)
  if not ok then
    return "Can't get followers of " .. user .. ': ' .. msg
  end
  return splash:evaljs([[
    document.querySelector('div.profile td.stat.stat-last div.statnum').innerText;
  ]]);
end

function process(splash, users)
  local result = {}
  for idx, user in ipairs(users) do
    result[user] = follow(splash, user)
  end
  return result
end

function main(splash)
  return {
    users=process(splash, USERS),
  }
end

Observations:

some Lua knowledge is helpful to be productive in Splash Scripts: ipairs, [[multi-line strings]] or string concatenation via .. could be unfamiliar;
in Splash variant followers function can return a result (a number of twitter followers); also, it doesn’t need a “callback” argument;
instead of a page.open callback which receives “status” argument there is a “blocking” splash:go call which returns “ok” flag;
error handling is different: in case of an HTTP 4xx or 5xx error PhantomJS doesn’t return an error code to page.open callback - example script will try to get the followers nevertheless because “status” won’t be “fail”; in Splash this error will be detected and ”?” will be returned;
process function can use a standard Lua for loop without a need to create a recursive callback chain;
instead of console messages we’ve got a JSON HTTP API;
apparently, PhantomJS allows to create multiple page objects and run several page.open requests in parallel (?); Splash only provides a single “browser tab” to a script via its splash parameter of main function (but you’re free to send multiple concurrent requests with Lua scripts to Splash).

There are great PhantomJS wrappers like CasperJS and NightmareJS which (among other things) bring a sync-looking syntax to PhantomJS scripts by providing custom control flow mini-languages. However, they all have their own gotchas and edge cases (loops? moving code to helper functions? error handling?). Splash scripts are standard Lua code.

Note

PhantomJS itself and its wrappers are great, they deserve lots of respect; please don’t take this writeup as an attack on them. These tools are much more mature and feature complete than Splash. Splash tries to look at the problem from a different angle, but for each unique Splash feature there are ten unique PhantomJS features.

Living Without Callbacks¶

Note

For the curious, Splash uses Lua coroutines under the hood.

Internally, “main” function is executed as a coroutine by Splash, and some of the splash:foo() methods use coroutine.yield. See http://www.lua.org/pil/9.html for Lua coroutines tutorial.

In Splash scripts it is not explicit which calls are async and which calls are blocking; this is a common criticism of coroutines/greenlets. Check this article for a good description of the problem.

However, these negatives have no real impact in Splash scripts which: are meant to be small, where shared state is minimized, and the API is designed to execute a single command at a time, so in most cases the control flow is linear.

If you want to be safe then think of all splash methods as async; consider that after you call splash:foo() a webpage being rendered can change. Often that’s the point of calling a method, e.g. splash:wait(time) or splash:go(url) only make sense because webpage changes after calling them, but still - keep it in mind.

There are async methods like splash:go, splash:wait, splash:wait_for_resume, etc.; most splash methods are currently not async, but thinking of them as of async will allow your scripts to work if we ever change that.

Calling Splash Methods¶

Unlike in many languages, methods in Lua are usually separated from an object using a colon :; to call “foo” method of “splash” object use splash:foo() syntax. See http://www.lua.org/pil/16.html for more details.

There are two main ways to call Lua methods in Splash scripts: using positional and named arguments. To call a method using positional arguments use parentheses splash:foo(val1, val2), to call it with named arguments use curly braces: splash:foo{name1=val1, name2=val2}:

-- Examples of positional arguments:
splash:go("http://example.com")
splash:wait(0.5, false)
local title = splash:evaljs("document.title")

-- The same using keyword arguments:
splash:go{url="http://example.com"}
splash:wait{time=0.5, cancel_on_redirect=false}
local title = splash:evaljs{source="document.title"}

-- Mixed arguments example:
splash:wait{0.5, cancel_on_redirect=false}

For convenience all splash methods are designed to support both styles of calling: positional and named. But since there are no “real” named arguments in Lua most Lua functions (including the ones from the standard library) choose to support just positional arguments.

Error Handling¶

There are two ways to report errors in Lua: raise an exception and return an error flag. See http://www.lua.org/pil/8.3.html.

Splash uses the following convention:

for developer errors (e.g. incorrect function arguments) exception is raised;
for errors outside developer control (e.g. a non-responding remote website) status flag is returned: functions that can fail return ok, reason pairs which developer can either handle or ignore.

If main results in an unhandled exception then Splash returns HTTP 400 response with an error message.

It is possible to raise an exception manually using Lua error function:

error("A message to be returned in a HTTP 400 response")

To handle Lua exceptions (and prevent Splash from returning HTTP 400 response) use Lua pcall; see http://www.lua.org/pil/8.4.html.

To convert “status flag” errors to exceptions Lua assert function can be used. For example, if you expect a website to work and don’t want to handle errors manually, then assert allows to stop processing and return HTTP 400 if the assumption is wrong:

local ok, msg = splash:go("http://example.com")
if not ok then
    -- handle error somehow, e.g.
    error(msg)
end

-- a shortcut for the code above: use assert
assert(splash:go("http://example.com"))

Sandbox¶

By default Splash scripts are executed in a restricted environment: not all standard Lua modules and functions are available, Lua require is restricted, and there are resource limits (quite loose though).

To disable the sandbox start Splash with --disable-lua-sandbox option:

$ python -m splash.server --disable-lua-sandbox

Timeouts¶

By default Splash aborts script execution after a timeout (30s by default); it is a common problem for long scripts.

For more information see I’m getting lots of 504 Timeout errors, please help! and 2. Splash Lua script does too many things.

Splash Scripts Reference¶

Warning

Scripting support is an experimental feature for early adopters; API could change in future releases.

splash object is passed to main function; via this object a script can control the browser. Think of it as of an API to a single browser tab.

Attributes¶

splash.args¶

splash.args is a table with incoming parameters. It contains merged values from the orignal URL string (GET arguments) and values sent using application/json POST request.

splash.js_enabled¶

Enable or disable execution of JavaSript code embedded in the page.

Signature: splash.js_enabled = true/false

JavaScript execution is enabled by default.

splash.private_mode_enabled¶

Enable or disable browser’s private mode (incognito mode).

Signature: splash.private_mode_enabled = true/false

Private mode is enabled by default unless you pass flag --disable-private-mode at Splash startup. Note that if you disable private mode browsing data such as cookies or items kept in local storage may persist between requests.

splash.resource_timeout¶

Set a default timeout for network requests, in seconds.

Signature: splash.resource_timeout = number

Example - abort requests to remote resources if they take more than 10 seconds:

function main(splash)
    splash.resource_timeout = 10.0
    assert(splash:go(splash.args.url))
    return splash:png()
end

Zero or nil value means “no timeout”.

Request timeouts set in splash:on_request using request:set_timeout have a priority over splash.resource_timeout.

splash.images_enabled¶

Enable/disable images.

Signature: splash.images_enabled = true/false

By default, images are enabled. Disabling of the images can save a lot of network traffic (usually around ~50%) and make rendering faster. Note that this option can affect the JavaScript code inside page: disabling of the images may change sizes and positions of DOM elements, and scripts may read and use them.

Splash uses in-memory cache; cached images will be displayed even when images are disabled. So if you load a page, then disable images, then load a new page, then likely first page will display all images and second page will display some images (the ones common with the first page). Splash cache is shared between scripts executed in the same process, so you can see some images even if they are disabled at the beginning of the script.

Example:

function main(splash)
    splash.images_enabled = false
    assert(splash:go(splash.args.url))
    return {png=splash:png()}
end

Methods¶

splash:go¶

Go to an URL. This is similar to entering an URL in a browser address bar, pressing Enter and waiting until page loads.

Signature: ok, reason = splash:go{url, baseurl=nil, headers=nil, http_method="GET", body=nil, formdata=nil}

Parameters:

url - URL to load;
baseurl - base URL to use, optional. When baseurl argument is passed the page is still loaded from url, but it is rendered as if it was loaded from baseurl: relative resource paths will be relative to baseurl, and the browser will think baseurl is in address bar;
headers - a Lua table with HTTP headers to add/replace in the initial request.
http_method - optional, string with HTTP method to use when visiting url, defaults to GET, Splash also supports POST.
body - optional, string with body for POST request
formdata - Lua table that will be converted to urlencoded POST body and sent with header content-type: application/x-www-form-urlencoded

Returns: ok, reason pair. If ok is nil then error happened during page load; reason provides an information about error type.

Async: yes, unless the navigation is locked.

Five types of errors are reported (ok can be nil in 5 cases):

There is a network error: a host doesn’t exist, server dropped connection, etc. In this case reason is "network<code>". A list of possible error codes can be found in Qt docs. For example, "network3" means a DNS error (invalid hostname).
Server returned a response with 4xx or 5xx HTTP status code. reason is "http<code>" in this case, i.e. for HTTP 404 Not Found reason is "http404".
Navigation is locked (see splash:lock_navigation); reason is "navigation_locked".
Splash can’t render the main page (e.g. because the first request was aborted) - reason is render_error.
If Splash can’t decide what caused the error, just "error" is returned.

Error handling example:

local ok, reason = splash:go("http://example.com")
if not ok then
    if reason:sub(0,4) == 'http' then
        -- handle HTTP errors
    else
        -- handle other errors
    end
end
-- process the page

-- assert can be used as a shortcut for error handling
assert(splash:go("http://example.com"))

Errors (ok==nil) are only reported when “main” webpage request failed. If a request to a related resource failed then no error is reported by splash:go. To detect and handle such errors (e.g. broken image/js/css links, ajax requests failed to load) use splash:har or splash:on_response.

splash:go follows all HTTP redirects before returning the result, but it doesn’t follow HTML <meta http-equiv="refresh" ...> redirects or redirects initiated by JavaScript code. To give the webpage time to follow those redirects use splash:wait.

headers argument allows to add or replace default HTTP headers for the initial request. To set custom headers for all further requests (including requests to related resources) use splash:set_custom_headers or splash:on_request.

Custom headers example:

local ok, reason = splash:go{"http://example.com", headers={
    ["Custom-Header"] = "Header Value",
}})

User-Agent header is special: once used, it is kept for further requests. This is an implementation detail and it could change in future releases; to set User-Agent header it is recommended to use splash:set_user_agent method.

splash:wait¶

Wait for time seconds. When script is waiting WebKit continues processing the webpage.

Signature: ok, reason = splash:wait{time, cancel_on_redirect=false, cancel_on_error=true}

Parameters:

time - time to wait, in seconds;
cancel_on_redirect - if true (not a default) and a redirect happened while waiting, then splash:wait stops earlier and returns nil, "redirect". Redirect could be initiated by <meta http-equiv="refresh" ...> HTML tags or by JavaScript code.
cancel_on_error - if true (default) and an error which prevents page from being rendered happened while waiting (e.g. an internal WebKit error or a network error like a redirect to a non-resolvable host) then splash:wait stops earlier and returns nil, "<error string>".

Returns: ok, reason pair. If ok is nil then the timer was stopped prematurely, and reason contains a string with a reason.

Async: yes.

Usage example:

-- go to example.com, wait 0.5s, return rendered html, ignore all errors.
function main(splash)
    splash:go("http://example.com")
    splash:wait(0.5)
    return {html=splash:html()}
end

By default wait timer continues to tick when redirect happens. cancel_on_redirect option can be used to restart the timer after each redirect. For example, here is a function that waits for a given time after each page load in case of redirects:

function wait_restarting_on_redirects(splash, time, max_redirects)
    local redirects_remaining = max_redirects
    while redirects_remaining > 0 do
        local ok, reason = self:wait{time=time, cancel_on_redirect=true}
        if reason ~= 'redirect' then
            return ok, reason
        end
        redirects_remaining = redirects_remaining - 1
    end
    return nil, "too_many_redirects"
end

splash:jsfunc¶

Convert JavaScript function to a Lua callable.

Signature: lua_func = splash:jsfunc(func)

Parameters:

func - a string which defines a JavaScript function.

Returns: a function that can be called from Lua to execute JavaScript code in page context.

Async: no.

Example:

function main(splash)
  local get_div_count = splash:jsfunc([[
    function () {
      var body = document.body;
      var divs = body.getElementsByTagName('div');
      return divs.length;
    }
  ]])

  local url = splash.args.url
  splash:go(url)
  return string.format("There are %s DIVs in %s",
      get_div_count(), url)
end

Note how Lua [[ ]] string syntax is helpful here.

JavaScript functions may accept arguments:

local vec_len = splash:jsfunc([[
    function(x, y) {
       return Math.sqrt(x*x + y*y)
    }
]])
return {res=vec_len(5, 4)}

Global JavaScript functions can be wrapped directly:

local pow = splash:jsfunc("Math.pow")
local twenty_five = pow(5, 2)  -- 5^2 is 25
local thousand = pow(10, 3)    -- 10^3 is 1000

Lua strings, numbers, booleans and tables can be passed as arguments; they are converted to JS strings/numbers/booleans/objects. Currently it is not possible to pass other Lua objects. For example, it is not possible to pass a wrapped JavaScript function or a regular Lua function as an argument to another wrapped JavaScript function.

Lua → JavaScript conversion rules:

Lua	JavaScript
string	string
number	number
boolean	boolean
table	Object or Array, see below
nil	undefined

Function result is converted from JavaScript to Lua data type. Only simple JS objects are supported. For example, returning a function or a JQuery selector from a wrapped function won’t work.

By default Lua tables are converted to JavaScript Objects. To convert a table to an Array use treat.as_array.

JavaScript → Lua conversion rules:

JavaScript	Lua
string	string
number	number
boolean	boolean
Object	table
Array	table, marked as array (see treat.as_array)
`undefined`	`nil`
`null`	`""` (an empty string)
Date	string: date’s ISO8601 representation, e.g. `1958-05-21T10:12:00.000Z`
function	`nil`
circular object	`nil`
host object	`nil`

Note

The rule of thumb: if an argument or a return value can be serialized via JSON, then it is fine.

Note that currently you can’t return DOM Elements, JQuery $ results and similar structures from JavaScript to Lua; to pass data you have to extract their attributes of interest as plain strings/numbers/objects/arrays:

-- this function assumes jQuery is loaded in page
local get_hrefs = splash:jsfunc([[
    function(sel){
        return $(sel).map(function(){return this.href}).get();
    }
]])
local hrefs = get_hrefs("a.story-title")

Function arguments and return values are passed by value. For example, if you modify an argument from inside a JavaScript function then the caller Lua code won’t see the changes, and if you return a global JS object and modify it in Lua then object won’t be changed in webpage context.

If a JavaScript function throws an error, it is re-throwed as a Lua error. To handle errors it is better to use JavaScript try/catch because some of the information about the error can be lost in JavaScript → Lua conversion.

splash:evaljs¶

Execute a JavaScript snippet in page context and return the result of the last statement.

Signature: result = splash:evaljs(snippet)

Parameters:

snippet - a string with JavaScript source code to execute.

Returns: the result of the last statement in snippet, converted from JavaScript to Lua data types. In case of syntax errors or JavaScript exceptions an error is raised.

Async: no.

JavaScript → Lua conversion rules are the same as for splash:jsfunc.

splash:evaljs is useful for evaluation of short JavaScript snippets without defining a wrapper function. Example:

local title = splash:evaljs("document.title")

Don’t use splash:evaljs when the result is not needed - it is inefficient and could lead to problems; use splash:runjs instead. For example, the following innocent-looking code (using jQuery) will do unnecessary work:

splash:evaljs("$(console.log('foo'));")

A gotcha is that to allow chaining jQuery $ function returns a huge object, splash:evaljs tries to serialize it and convert to Lua, which is a waste of resources. splash:runjs doesn’t have this problem.

If the code you’re evaluating needs arguments it is better to use splash:jsfunc instead of splash:evaljs and string formatting. Compare:

function main(splash)

    local font_size = splash:jsfunc([[
        function(sel) {
            var el = document.querySelector(sel);
            return getComputedStyle(el)["font-size"];
        }
    ]])

    local font_size2 = function(sel)
        -- FIXME: escaping of `sel` parameter!
        local js = string.format([[
            var el = document.querySelector("%s");
            getComputedStyle(el)["font-size"]
        ]], sel)
        return splash:evaljs(js)
    end

    -- ...
end

splash:runjs¶

Run JavaScript code in page context.

Signature: ok, error = splash:runjs(snippet)

Parameters:

snippet - a string with JavaScript source code to execute.

Returns: ok, error pair. When the execution is successful ok is True. In case of JavaScript errors ok is nil, and error contains the error string.

Async: no.

Example:

assert(splash:runjs("document.title = 'hello';"))

Note that JavaScript functions defined using function foo(){} syntax won’t be added to the global scope:

assert(splash:runjs("function foo(){return 'bar'}"))
local res = splash:evaljs("foo()")  -- this raises an error

It is an implementation detail: the code passed to splash:runjs is executed in a closure. To define functions use global variables, e.g.:

assert(splash:runjs("foo = function (){return 'bar'}"))
local res = splash:evaljs("foo()")  -- this returns 'bar'

If the code needs arguments it is better to use splash:jsfunc. Compare:

function main(splash)

    -- Lua function to scroll window to (x, y) position.
    function scroll_to(x, y)
        local js = string.format(
            "window.scrollTo(%s, %s);",
            tonumber(x),
            tonumber(y)
        )
        assert(splash:runjs(js))
    end

    -- a simpler version using splash:jsfunc
    local scroll_to2 = splash:jsfunc("window.scrollTo")

    -- ...
end

splash:wait_for_resume¶

Run asynchronous JavaScript code in page context. The Lua script will yield until the JavaScript code tells it to resume.

Signature: result, error = splash:wait_for_resume(snippet, timeout)

Parameters:

snippet - a string with a JavaScript source code to execute. This code must include a function called main. The first argument to main is an object that has the properties resume and error. resume is a function which can be used to resume Lua execution. It takes an optional argument which will be returned to Lua in the result.value return value. error is a function which can be called with a required string value that is returned in the error return value.
timeout - a number which determines (in seconds) how long to allow JavaScript to execute before forceably returning control to Lua. Defaults to zero, which disables the timeout.

Returns: result, error pair. When the execution is successful result is a table. If the value returned by JavaScript is not undefined, then the result table will contain a key value that has the value passed to splash.resume(…). The result table also contains any additional key/value pairs set by splash.set(…). In case of timeout or JavaScript errors result is nil and error contains an error message string.

Async: yes.

Examples:

The first, trivial example shows how to transfer control of execution from Lua to JavaScript and then back to Lua. This command will tell JavaScript to sleep for 3 seconds and then return to Lua. Note that this is an async operation: the Lua event loop and the JavaScript event loop continue to run during this 3 second pause, but Lua will not continue executing the current function until JavaScript calls splash.resume().

function main(splash)

    local result, error = splash:wait_for_resume([[
        function main(splash) {
            setTimeout(function () {
                splash.resume();
            }, 3000);
        }
    ]])

    -- result is {}
    -- error is nil

end

result is set to an empty table to indicate that nothing was returned from splash.resume. You can use assert(splash:wait_for_resume(…)) even when JavaScript does not return a value because the empty table signifies success to assert().

Note

Your JavaScript code must contain a main() function. You will get an error if you do not include it. The first argument to this function can have any name you choose, of course. We will call it splash by convention in this documentation.

The next example shows how to return a value from JavaScript to Lua. You can return booleans, numbers, strings, arrays, or objects.

function main(splash)

    local result, error = splash:wait_for_resume([[
        function main(splash) {
            setTimeout(function () {
                splash.resume([1, 2, 'red', 'blue']);
            }, 3000);
        }
    ]])

    -- result is {value={1, 2, 'red', 'blue'}}
    -- error is nil

end

Note

As with splash:evaljs, be wary of returning objects that are too large, such as the $ object in jQuery, which will consume a lot of time and memory to convert to a Lua result.

You can also set additional key/value pairs in JavaScript with the splash.set(key, value) function. Key/value pairs will be included in the result table returned to Lua. The following example demonstrates this.

function main(splash)

    local result, error = splash:wait_for_resume([[
        function main(splash) {
            setTimeout(function () {
                splash.set("foo", "bar");
                splash.resume("ok");
            }, 3000);
        }
    ]])

    -- result is {foo="bar", value="ok"}
    -- error is nil

end

The next example shows an incorrect usage of splash:wait_for_resume(): the JavaScript code does not contain a main() function. result is nil because splash.resume() is never called, and error contains an error message explaining the mistake.

function main(splash)

    local result, error = splash:wait_for_resume([[
        console.log('hello!');
    ]])

    -- result is nil
    -- error is "error: wait_for_resume(): no main() function defined"

end

The next example shows error handling. If splash.error(…) is called instead of splash.resume(), then result will be nil and error will contain the string passed to splash.error(…).

function main(splash)

    local result, error = splash:wait_for_resume([[
        function main(splash) {
            setTimeout(function () {
                splash.error("Goodbye, cruel world!");
            }, 3000);
        }
    ]])

    -- result is nil
    -- error is "error: Goodbye, cruel world!"

end

Your JavaScript code must either call splash.resume() or splash.error() exactly one time. Subsequent calls to either function have no effect, as shown in the next example.

function main(splash)

    local result, error = splash:wait_for_resume([[
        function main(splash) {
            setTimeout(function () {
                splash.resume("ok");
                splash.resume("still ok");
                splash.error("not ok");
            }, 3000);
        }
    ]])

    -- result is {value="ok"}
    -- error is nil

end

The next example shows the effect of the timeout argument. We have set the timeout argument to 1 second, but our JavaScript code will not call splash.resume() for 3 seconds, which guarantees that splash:wait_for_resume() will time out.

When it times out, result will be nil, error will contain a string explaining the timeout, and Lua will continue executing. Calling splash.resume() or splash.error() after a timeout has no effect.

function main(splash)

    local result, error = splash:wait_for_resume([[
        function main(splash) {
            setTimeout(function () {
                splash.resume("Hello, world!");
            }, 3000);
        }
    ]], 1)

    -- result is nil
    -- error is "error: One shot callback timed out while waiting for resume() or error()."

end

Note

The timeout must be >= 0. If the timeout is 0, then splash:wait_for_resume() will never timeout (although Splash’s HTTP timeout still applies).

Note that your JavaScript code is not forceably canceled by a timeout: it may continue to run until Splash shuts down the entire browser context.

splash:autoload¶

Set JavaScript to load automatically on each page load.

Signature: ok, reason = splash:autoload{source_or_url, source=nil, url=nil}

Parameters:

source_or_url - either a string with JavaScript source code or an URL to load the JavaScript code from;
source - a string with JavaScript source code;
url - an URL to load JavaScript source code from.

Returns: ok, reason pair. If ok is nil, error happened and reason contains an error description.

Async: yes, but only when an URL of a remote resource is passed.

splash:autoload allows to execute JavaScript code at each page load. splash:autoload doesn’t doesn’t execute the passed JavaScript code itself. To execute some code once, after page is loaded use splash:runjs or splash:jsfunc.

splash:autoload can be used to preload utility JavaScript libraries or replace JavaScript objects before a webpage has a chance to do it.

Example:

function main(splash)
    splash:autoload([[
        function get_document_title(){
           return document.title;
        }
    ]])
    assert(splash:go(splash.args.url))
    return splash:evaljs("get_document_title()")
end

For the convenience, when a first splash:autoload argument starts with “http://” or “https://” a script from the passed URL is loaded. Example 2 - make sure a remote library is available:

function main(splash)
    assert(splash:autoload("https://code.jquery.com/jquery-2.1.3.min.js"))
    assert(splash:go(splash.args.url))
    local version = splash:evaljs("$.fn.jquery")
    return 'JQuery version: ' .. version
end

To disable URL auto-detection use ‘source’ and ‘url’ arguments:

splash:autoload{url="https://code.jquery.com/jquery-2.1.3.min.js"}
splash:autoload{source="window.foo = 'bar';"}

It is a good practice not to rely on auto-detection when the argument is not a constant.

If splash:autoload is called multiple times then all its scripts are executed on page load, in order they were added.

To revert Splash not to execute anything on page load use splash:autoload_reset.

splash:autoload_reset¶

Unregister all scripts previously set by splash:autoload.

Signature: splash:autoload_reset()

Returns: nil

Async: no

After splash:autoload_reset call scripts set by splash:autoload won’t be loaded in future requests; one can use splash:autoload again to setup a different set of scripts.

Already loaded scripts are not removed from the current page context.

splash:call_later¶

Arrange for the callback to be called after the given delay seconds.

Signature: timer = splash:call_later(callback, delay)

Parameters:

callback - function to run;
delay - delay, in seconds;

Returns: a handle which allows to cancel pending timer or reraise exceptions happened in a callback.

Async: no.

Example 1 - take two HTML snapshots, at 1.5s and 2.5s after page loading starts:

function main(splash)
    local snapshots = {}
    local timer = splash:call_later(function()
        snapshots["a"] = splash:html()
        splash:wait(1.0)
        snapshots["b"] = splash:html()
    end, 1.5)
    assert(splash:go(splash.args.url))
    splash:wait(3.0)
    timer:reraise()
    return snapshots
end

splash:call_later returns a handle (a timer). To cancel pending task use its timer:cancel() method. If a callback is already started timer:cancel() has no effect.

By default, exceptions raised in splash:call_later callback stop the callback, but don’t stop the main script. To reraise these errors use timer:reraise().

splash:call_later arranges callback to be executed in future; it never runs it immediately, even if delay is 0. When delay is 0 callback is executed no earlier than current function yields to event loop, i.e. no earlier than some of the async functions is called.

splash:http_get¶

Send an HTTP GET request and return a response without loading the result to the browser window.

Signature: response = splash:http_get{url, headers=nil, follow_redirects=true}

Parameters:

url - URL to load;
headers - a Lua table with HTTP headers to add/replace in the initial request;
follow_redirects - whether to follow HTTP redirects.

Returns: a Response Object.

Async: yes.

Example:

local reply = splash:http_get("http://example.com")

This method doesn’t change the current page contents and URL. To load a webpage to the browser use splash:go.

splash:http_post¶

Send an HTTP POST request and return a response without loading the result to the browser window.

Signature: response = splash:http_post{url, headers=nil, follow_redirects=true, body=nil}

Parameters:

url - URL to load;
headers - a Lua table with HTTP headers to add/replace in the initial request;
follow_redirects - whether to follow HTTP redirects.
body - string with body of request, if you intend to send form submission, body should be urlencoded.

Returns: a Response Object.

Async: yes.

Example of form submission:

local reply = splash:http_post{url="http://example.com", body="user=Frank&password=hunter2"}
-- reply.body contains raw HTML data (as a binary object)
-- reply.status contains HTTP status code, as a number
-- see Response docs for more info

Example of JSON POST request:

json = require("json")

local reply = splash:http_post{
    url="http://example.com/post",
    body=json.encode({alpha="beta"}),
    headers={["content-type"]="application/json"}
}

This method doesn’t change the current page contents and URL. To load a webpage to the browser use splash:go.

See also: splash:http_get, json, Response Object.

splash:set_content¶

Set the content of the current page and wait until the page loads.

Signature: ok, reason = splash:set_content{data, mime_type="text/html; charset=utf-8", baseurl=""}

Parameters:

data - new page content;
mime_type - MIME type of the content;
baseurl - external objects referenced in the content are located relative to baseurl.

Returns: ok, reason pair. If ok is nil then error happened during page load; reason provides an information about error type.

Async: yes.

Example:

function main(splash)
    assert(splash:set_content("<html><body><h1>hello</h1></body></html>"))
    return splash:png()
end

splash:html¶

Return a HTML snapshot of a current page (as a string).

Signature: html = splash:html()

Returns: contents of a current page (as a string).

Async: no.

Example:

-- A simplistic implementation of render.html endpoint
function main(splash)
    splash:set_result_content_type("text/html; charset=utf-8")
    assert(splash:go(splash.args.url))
    return splash:html()
end

Nothing prevents us from taking multiple HTML snapshots. For example, let’s visit first 3 pages on a website, and for each page store initial HTML snapshot and an HTML snapshot after waiting 0.5s:

treat = require("treat")

-- Given an url, this function returns a table
-- with the page screenshoot, it's HTML contents
-- and it's title.
function page_info(splash, url)
    local ok, msg = splash:go(url)
    if not ok then
        return {ok=false, reason=msg}
    end
    local res = {
        html=splash:html(),
        title=splash:evaljs('document.title'),
        image=splash:png(),
        ok=true,
    }
    return res
end

-- visit first 3 pages of hacker news
local base = "https://news.ycombinator.com/news?p="
function main(splash)
    local result = treat.as_array({})
    for i=1,3 do
        local url =  base .. i
        result[i] = page_info(splash, url)
    end
    return result
end

splash:png¶

Return a width x height screenshot of a current page in PNG format.

Signature: png = splash:png{width=nil, height=nil, render_all=false, scale_method='raster'}

Parameters:

width - optional, width of a screenshot in pixels;
height - optional, height of a screenshot in pixels;
render_all - optional, if true render the whole webpage;
scale_method - optional, method to use when resizing the image, 'raster' or 'vector'

Returns: PNG screenshot data, as a binary object.

Async: no.

Without arguments splash:png() will take a snapshot of the current viewport.

width parameter sets the width of the resulting image. If the viewport has a different width, the image is scaled up or down to match the specified one. For example, if the viewport is 1024px wide then splash:png{width=100} will return a screenshot of the whole viewport, but the image will be downscaled to 100px width.

height parameter sets the height of the resulting image. If the viewport has a different height, the image is trimmed or extended vertically to match the specified one without resizing the content. The region created by such extension is transparent.

To set the viewport size use splash:set_viewport_size, splash:set_viewport_full or render_all argument. render_all=true is equivalent to running splash:set_viewport_full() just before the rendering and restoring the viewport size afterwards.

scale_method parameter must be either 'raster' or 'vector'. When scale_method='raster', the image is resized per-pixel. When scale_method='vector', the image is resized per-element during rendering. Vector scaling is more performant and produces sharper images, however it may cause rendering artifacts, so use it with caution.

The result of splash:png is a binary object, so you can return it directly from “main” function and it will be sent as a binary image data with a proper Content-Type header:

-- A simplistic implementation of render.png endpoint
function main(splash)
   assert(splash:go(splash.args.url))
   return splash:png{
      width=splash.args.width,
      height=splash.args.height
   }
end

If the result of splash:png() is returned as a table value, it is encoded to base64 to make it possible to embed in JSON and build a data:uri on a client (magic!):

function main(splash)
    assert(splash:go(splash.args.url))
    return {png=splash:png()}
end

If your script returns the result of splash:png() in a top-level "png" key (as we’ve done in a previous example) then Splash UI will display it as an image.

splash:jpeg¶

Return a width x height screenshot of a current page in JPEG format.

Signature: jpeg = splash:jpeg{width=nil, height=nil, render_all=false, scale_method='raster', quality=75}

Parameters:

width - optional, width of a screenshot in pixels;
height - optional, height of a screenshot in pixels;
render_all - optional, if true render the whole webpage;
scale_method - optional, method to use when resizing the image, 'raster' or 'vector'
quality - optional, quality of JPEG image, integer in range from 0 to 100

Returns: JPEG screenshot data, as a binary object.

Async: no.

Without arguments splash:jpeg() will take a snapshot of the current viewport.

width parameter sets the width of the resulting image. If the viewport has a different width, the image is scaled up or down to match the specified one. For example, if the viewport is 1024px wide then splash:jpeg{width=100} will return a screenshot of the whole viewport, but the image will be downscaled to 100px width.

height parameter sets the height of the resulting image. If the viewport has a different height, the image is trimmed or extended vertically to match the specified one without resizing the content. The region created by such extension is white.

To set the viewport size use splash:set_viewport_size, splash:set_viewport_full or render_all argument. render_all=true is equivalent to running splash:set_viewport_full() just before the rendering and restoring the viewport size afterwards.

scale_method parameter must be either 'raster' or 'vector'. When scale_method='raster', the image is resized per-pixel. When scale_method='vector', the image is resized per-element during rendering. Vector scaling is more performant and produces sharper images, however it may cause rendering artifacts, so use it with caution.

quality parameter must be an integer in range from 0 to 100. Values above 95 should be avoided; quality=100 disables portions of the JPEG compression algorithm, and results in large files with hardly any gain in image quality.

The result of splash:jpeg is a binary object, so you can return it directly from “main” function and it will be sent as a binary image data with a proper Content-Type header:

-- A simplistic implementation of render.jpeg endpoint
function main(splash)
    assert(splash:go(splash.args.url))
    return splash:jpeg{
       width=splash.args.width,
       height=splash.args.height
    }
end

If the result of splash:jpeg() is returned as a table value, it is encoded to base64 to make it possible to embed in JSON and build a data:uri on a client:

function main(splash)
    assert(splash:go(splash.args.url))
    return {jpeg=splash:jpeg()}
end

Note that splash:jpeg() is often 1.5..2x faster than splash:png().

splash:har¶

Signature: har = splash:har{reset=false}

Parameters:

reset - optional; when true, reset HAR records after taking a snapshot.

Returns: information about pages loaded, events happened, network requests sent and responses received in HAR format.

Async: no.

Use splash:har to get information about network requests and other Splash activity.

If your script returns the result of splash:har() in a top-level "har" key then Splash UI will give you a nice diagram with network information (similar to “Network” tabs in Firefox or Chrome developer tools):

function main(splash)
    assert(splash:go(splash.args.url))
    return {har=splash:har()}
end

By default, when several requests are made (e.g. splash:go is called multiple times), HAR data is accumulated and combined into a single object (logs are still grouped by page).

If you want only updated information use reset parameter: it drops all existing logs and start recording from scratch:

function main(splash)
    assert(splash:go(splash.args.url1))
    local har1 = splash:har{reset=true}
    assert(splash:go(splash.args.url2))
    local har2 = splash:har()
    return {har1=har1, har2=har2}
end

splash:har_reset¶

Signature: splash:har_reset()

Returns: nil.

Async: no.

Drops all internally stored HAR records. It is similar to splash:har{reset=true}, but doesn’t return anything.

splash:history¶

Signature: entries = splash:history()

Returns: information about requests/responses for the pages loaded, in HAR entries format.

Async: no.

splash:history doesn’t return information about related resources like images, scripts, stylesheets or AJAX requests. If you need this information use splash:har or splash:on_response.

Let’s get a JSON array with HTTP headers of the response we’re displaying:

function main(splash)
    assert(splash:go(splash.args.url))
    local entries = splash:history()
    -- #entries means "entries length"; arrays in Lua start from 1
    local last_entry = entries[#entries]
    return {
       headers = last_entry.response.headers
    }
end

See also: splash:har, splash:on_response.

splash:url¶

Signature: url = splash:url()

Returns: the current URL.

Async: no.

splash:get_cookies¶

Signature: cookies = splash:get_cookies()

Returns: CookieJar contents - an array with all cookies available for the script. The result is returned in HAR cookies format.

Async: no.

Example result:

[
    {
        "name": "TestCookie",
        "value": "Cookie Value",
        "path": "/",
        "domain": "www.example.com",
        "expires": "2016-07-24T19:20:30+02:00",
        "httpOnly": false,
        "secure": false,
    }
]

splash:init_cookies¶

Replace all current cookies with the passed cookies.

Signature: splash:init_cookies(cookies)

Parameters:

cookies - a Lua table with all cookies to set, in the same format as splash:get_cookies returns.

Returns: nil.

Async: no.

Example 1 - save and restore cookies:

local cookies = splash:get_cookies()
-- ... do something ...
splash:init_cookies(cookies)  -- restore cookies

Example 2 - initialize cookies manually:

splash:init_cookies({
    {name="baz", value="egg"},
    {name="spam", value="egg", domain="example.com"},
    {
        name="foo",
        value="bar",
        path="/",
        domain="localhost",
        expires="2016-07-24T19:20:30+02:00",
        secure=true,
        httpOnly=true,
    }
})

-- do something
assert(splash:go("http://example.com"))

splash:clear_cookies¶

Clear all cookies.

Signature: n_removed = splash:clear_cookies()

Returns: a number of cookies deleted.

Async: no.

To delete only specific cookies use splash:delete_cookies.

splash:delete_cookies¶

Delete matching cookies.

Signature: n_removed = splash:delete_cookies{name=nil, url=nil}

Parameters:

name - a string, optional. All cookies with this name will be deleted.
url - a string, optional. Only cookies that should be sent to this url will be deleted.

Returns: a number of cookies deleted.

Async: no.

This function does nothing when both name and url are nil. To remove all cookies use splash:clear_cookies method.

splash:set_result_status_code¶

Set HTTP status code of a result returned to a client.

Signature: splash:set_result_status_code(code)

Parameters:

code - HTTP status code (a number 200 <= code <= 999).

Returns: nil.

Async: no.

Use this function to signal errors or other conditions to splash client using HTTP status codes.

Example:

function main(splash)
    local ok, reason = splash:go("http://www.example.com")
    if reason == "http500" then
        splash:set_result_status_code(503)
        splash:set_result_header("Retry-After", 10)
        return ''
    end
    return splash:png()
end

Be careful with this function: some proxies can be configured to process responses differently based on their status codes. See e.g. nginx proxy_next_upstream option.

In case of unhandled Lua errors HTTP status code is set to 400 regardless of the value set with splash:set_result_status_code.

splash:set_result_content_type¶

Set Content-Type of a result returned to a client.

Signature: splash:set_result_content_type(content_type)

Parameters:

content_type - a string with Content-Type header value.

Returns: nil.

Async: no.

If a table is returned by “main” function then splash:set_result_content_type has no effect: Content-Type of the result is set to application/json.

This function does not set Content-Type header for requests initiated by splash:go; this function is for setting Content-Type header of a result.

Example:

function main(splash)
    splash:set_result_content_type("text/xml")
    return [[
       <?xml version="1.0" encoding="UTF-8"?>
       <note>
           <to>Tove</to>
           <from>Jani</from>
           <heading>Reminder</heading>
           <body>Don't forget me this weekend!</body>
       </note>
    ]]
end

splash:set_result_header¶

Set header of result response returned to splash client.

Signature: splash:set_result_header(name, value)

Parameters:

name of response header
value of response header

Returns: nil.

Async: no.

This function does not set HTTP headers for responses returned by splash:go or requests initiated by splash:go; this function is for setting headers of splash response sent to client.

Example 1, set ‘foo=bar’ header:

function main(splash)
    splash:set_result_header("foo", "bar")
    return "hello"
end

Example 2, measure the time needed to build PNG screenshot and return it result in an HTTP header:

function main(splash)

    -- this function measures the time code takes to execute and returns
    -- it in an HTTP header
    function timeit(header_name, func)
        local start_time = splash:get_perf_stats().walltime
        local result = func()  -- it won't work for multiple returned values!
        local end_time = splash:get_perf_stats().walltime
        splash:set_result_header(header_name, tostring(end_time - start_time))
        return result
    end

    -- rendering script
    assert(splash:go(splash.args.url))
    local screenshot = timeit("X-Render-Time", function()
       return splash:png()
    end)
    splash:set_result_content_type("image/png")
    return screenshot
end

splash:get_viewport_size¶

Get the browser viewport size.

Signature: width, height = splash:get_viewport_size()

Returns: two numbers: width and height of the viewport in pixels.

Async: no.

splash:set_viewport_size¶

Set the browser viewport size.

Signature: splash:set_viewport_size(width, height)

Parameters:

width - integer, requested viewport width in pixels;
height - integer, requested viewport height in pixels.

Returns: nil.

Async: no.

This will change the size of the visible area and subsequent rendering commands, e.g., splash:png, will produce an image with the specified size.

splash:png uses the viewport size.

Example:

function main(splash)
    splash:set_viewport_size(1980, 1020)
    assert(splash:go("http://example.com"))
    return {png=splash:png()}
end

Note

This will relayout all document elements and affect geometry variables, such as window.innerWidth and window.innerHeight. However window.onresize event callback will only be invoked during the next asynchronous operation and splash:png is notably synchronous, so if you have resized a page and want it to react accordingly before taking the screenshot, use splash:wait.

splash:set_viewport_full¶

Resize browser viewport to fit the whole page.

Signature: width, height = splash:set_viewport_full()

Returns: two numbers: width and height the viewport is set to, in pixels.

Async: no.

splash:set_viewport_full should be called only after page is loaded, and some time passed after that (use splash:wait). This is an unfortunate restriction, but it seems that this is the only way to make automatic resizing work reliably.

See splash:set_viewport_size for a note about interaction with JS.

splash:png uses the viewport size.

Example:

function main(splash)
    assert(splash:go("http://example.com"))
    assert(splash:wait(0.5))
    splash:set_viewport_full()
    return {png=splash:png()}
end

splash:set_user_agent¶

Overwrite the User-Agent header for all further requests.

Signature: splash:set_user_agent(value)

Parameters:

value - string, a value of User-Agent HTTP header.

Returns: nil.

Async: no.

splash:set_custom_headers¶

Set custom HTTP headers to send with each request.

Signature: splash:set_custom_headers(headers)

Parameters:

headers - a Lua table with HTTP headers.

Returns: nil.

Async: no.

Headers are merged with WebKit default headers, overwriting WebKit values in case of conflicts.

When headers argument of splash:go is used headers set with splash:set_custom_headers are not applied to the initial request: values are not merged, headers argument of splash:go has higher priority.

Example:

splash:set_custom_headers({
   ["Header-1"] = "Value 1",
   ["Header-2"] = "Value 2",
})

Note

Named arguments are not supported for this function.

splash:get_perf_stats¶

Return performance-related statistics.

Signature: stats = splash:get_perf_stats()

Returns: a table that can be useful for performance analysis.

Async: no.

As of now, this table contains:

walltime - (float) number of seconds since epoch, analog of os.clock
cputime - (float) number of cpu seconds consumed by splash process
maxrss - (int) high water mark number of bytes of RAM consumed by splash process

splash:on_request¶

Register a function to be called before each HTTP request.

Signature: splash:on_request(callback)

Parameters:

callback - Lua function to call before each HTTP request.

Returns: nil.

Async: no.

splash:on_request callback receives a single request argument (a Request Object).

To get information about a request use request attributes; to change or drop the request before sending use request methods;

A callback passed to splash:on_request can’t call Splash async methods like splash:wait or splash:go.

Example 1 - log all URLs requested using request.url attribute:

treat = require("treat")
function main(splash)
    local urls = {}
    splash:on_request(function(request)
        table.insert(urls, request.url)
    end)
    assert(splash:go(splash.args.url))
    return treat.as_array(urls)
end

Example 2 - to log full request information use request.info attribute; don’t store request objects directly:

treat = require("treat")
function main(splash)
    local entries = treat.as_array({})
    splash:on_request(function(request)
        table.insert(entries, request.info)
    end)
    assert(splash:go(splash.args.url))
    return entries
end

Example 3 - drop all requests to resources containing ”.css” in their URLs (see request:abort):

splash:on_request(function(request)
    if string.find(request.url, ".css") ~= nil then
        request.abort()
    end
end)

Example 4 - replace a resource (see request:set_url):

splash:on_request(function(request)
    if request.url == 'http://example.com/script.js' then
        request:set_url('http://mydomain.com/myscript.js')
    end
end)

Example 5 - set a custom proxy server, with credentials passed in an HTTP request to Splash (see request:set_proxy):

splash:on_request(function(request)
    request:set_proxy{
        host = "0.0.0.0",
        port = 8990,
        username = splash.args.username,
        password = splash.args.password,
    }
end)

Example 6 - discard requests which take longer than 5 seconds to complete, but allow up to 15 seconds for the first request (see request:set_timeout):

local first = true
splash.resource_timeout = 5
splash:on_request(function(request)
    if first then
        request:set_timeout(15.0)
        first = false
    end
end)

Note

splash:on_request doesn’t support named arguments.

splash:on_response_headers¶

Register a function to be called after response headers are received, before response body is read.

Signature: splash:on_response_headers(callback)

Parameters:

callback - Lua function to call for each response after response headers are received.

Returns: nil.

Async: no.

splash:on_response_headers callback receives a single response argument (a Response Object).

response.body is not available in a splash:on_response_headers callback because response body is not read yet. Thats the point of splash:on_response_headers method: you can abort reading of the response body using response:abort method.

A callback passed to splash:on_response_headers can’t call Splash async methods like splash:wait or splash:go. response object is deleted after exiting from a callback, so you cannot use it outside a callback.

Example 1 - log content-type headers of all responses received while rendering

function main(splash)
    local all_headers = {}
    splash:on_response_headers(function(response)
        local content_type = response.headers["Content-Type"]
        all_headers[response.url] = content_type
    end)
    assert(splash:go(splash.args.url))
    return all_headers
end

Example 2 - abort reading body of all responses with content type text/css

function main(splash)
    splash:on_response_headers(function(response)
        local content_type = response.headers["Content-Type"]
        if content_type == "text/css" then
            response.abort()
        end
    end)
    assert(splash:go(splash.args.url))
    return splash:png()
end

Example 3 - extract all cookies set by website without downloading response bodies

function main(splash)
    local cookies = ""
    splash:on_response_headers(function(response)
        local response_cookies = response.headers["Set-cookie"]
        cookies = cookies .. ";" .. response_cookies
        response.abort()
    end)
    assert(splash:go(splash.args.url))
    return cookies
end

Note

splash:on_response_headers doesn’t support named arguments.

splash:on_response¶

Register a function to be called after response is downloaded.

Signature: splash:on_response(callback)

Parameters:

callback - Lua function to call for each response after it is downloaded.

Returns: nil.

Async: no.

splash:on_response callback receives a single response argument (a Response Object).

Note

Currently you can’t access response.body in a splash:on_response callback.

Note

splash:on_response doesn’t support named arguments.

splash:on_request_reset¶

Remove all callbacks registered by splash:on_request.

Signature: splash:on_request_reset()

Returns: nil

Async: no.

splash:on_response_headers_reset¶

Remove all callbacks registered by splash:on_response_headers.

Signature: splash:on_response_headers_reset()

Returns: nil

Async: no.

splash:on_response_reset¶

Remove all callbacks registered by splash:on_response.

Signature: splash:on_response_reset()

Returns: nil

Async: no.

splash:get_version¶

Get Splash major and minor version.

Signature: version_info = splash:get_version()

Returns: A table with version information.

Async: no.

As of now, this table contains:

splash - (string) Splash version
major - (int) Splash major version
minor - (int) Splash minor version
python - (string) Python version
qt - (string) Qt version
pyqt - (string) PyQt version
webkit - (string) WebKit version
sip - (string) SIP version
twisted - (string) Twisted version

Example:

function main(splash)
     local version = splash:get_version()
     if version.major < 2 and version.minor < 8 then
         error("Splash 1.8 or newer required")
     end
 end

Response Object¶

Response objects are returned as a result of several Splash methods (like splash:http_get or splash:http_post); they are are also passed to some of the callbacks (e.g. splash:on_response and splash:on_response_headers callbacks). These objects contain information about a response.

response.url¶

URL of the response. In case of redirects response.url is a last URL.

This field is read-only.

response.status¶

HTTP status code of the response.

This field is read-only.

response.ok¶

true for successful responses and false when error happened.

Example:

local reply = splash:http_get("some-bad-url")
-- reply.ok == false

This field is read-only.

response.headers¶

A Lua table with HTTP headers (header name => header value). Keys are header names (strings), values are header values (strings).

Lookups are case-insensitive, so response.headers['content-type'] is the same as response.headers['Content-Type'].

This field is read-only.

response.info¶

A Lua table with response data in HAR response format.

This field is read-only.

response.body¶

Raw response body (a binary object).

If you want to process response body from Lua use treat.as_string to convert it to a Lua string first.

response.request¶

A corresponding Request Object.

This field is read-only.

response:abort¶

Signature: response:abort()

Returns: nil.

Async: no.

Abort reading of the response body. This method is only available if a response is not read yet - currently you can use it only in a splash:on_response_headers callback.

Request Object¶

Request objects are received by splash:on_request callbacks; they are also available as response.request.

Attributes¶

Request objects has several attributes with information about a HTTP request. These fields are for information only; changing them doesn’t change the request to be sent.

request.url¶

Requested URL.

request.method¶

HTTP method name in upper case, e.g. “GET”.

request.headers¶

A Lua table with request HTTP headers (header name => header value). Keys are header names (strings), values are header values (strings).

Lookups are case-insensitive, so request.headers['content-type'] is the same as request.headers['Content-Type'].

request.info¶

A table with request data in HAR request format.

Methods¶

To change or drop the request before sending use one of the request methods. Note that these methods are only available before the request is sent (they has no effect if a request is already sent). Currently it means you can only use them in splash:on_request callbacks.

request:abort¶

Drop the request.

Signature: request:abort()

Returns: nil.

Async: no.

request:set_url¶

Change request URL to a specified value.

Signature: request:set_url(url)

Parameters:

url - new request URL

Returns: nil.

Async: no.

request:set_proxy¶

Set a proxy server to use for this request.

Signature: request:set_proxy{host, port, username=nil, password=nil, type='HTTP'}

Parameters:

host
port
username
password
type - proxy type; allowed proxy types are ‘HTTP’ and ‘SOCKS5’.

Returns: nil.

Async: no.

Omit username and password arguments if a proxy doesn’t need auth.

When type is set to ‘HTTP’ HTTPS proxying should also work; it is implemented using CONNECT command.

request:set_timeout¶

Set a timeout for this request.

Signature: request:set_timeout(timeout)

Parameters:

timeout - timeout value, in seconds.

Returns: nil.

Async: no.

If response is not fully received after the timeout, request is aborted. See also: splash.resource_timeout.

request:set_header¶

Set an HTTP header for this request.

Signature: request:set_header(name, value)

Parameters:

name - header name;
value - header value.

Returns: nil.

Async: no.

Working with Binary Data¶

Motivation¶

Splash assumes that most strings in a script are encoded to UTF-8. This is true for HTML content - even if the original response was not UTF-8, internally browser works with UTF-8, so splash:html result is always UTF-8.

When you return a Lua table from the main function Splash encodes it to JSON; JSON is a text protocol which can’t handle arbitrary binary data, so Splash assumes all strings are UTF-8 when returning a JSON result.

But sometimes it is necessary to work with binary data: for example, it could be raw image data returned by splash:png or a response body of a non-UTF-8 page returned by splash:http_get.

Binary Objects¶

To pass non-UTF8 data to Splash (returning it as a result of main or passing as arguments to splash methods) a script may mark it as a binary object using treat.as_binary function.

Some of the Splash functions already return binary objects: splash:png, splash:jpeg; response.body attribute is also a binary object.

A binary object can be returned as a main result directly. It is the reason the following example works (a basic render.png implementation in Lua):

-- basic render.png emulation
function main(splash)
    assert(splash:go(splash.args.url))
    return splash:png()
end

All binary objects have content-type attached. For example, splash:png result will have content-type image/png.

When returned directly, a binary object data is used as-is for the response body, and Content-Type HTTP header is set to the content-type of a binary object. So in the previous example the result will be a PNG image with a proper Content-Type header.

To construct your own binary objects use treat.as_binary function. For example, let’s return a 1x1px black GIF image as a response:

treat = require("treat")
base64 = require("base64")

function main(splash)
    local gif_b64 = "AQABAIAAAAAAAAAAACH5BAAAAAAALAAAAAABAAEAAAICTAEAOw=="
    local gif_bytes = base64.decode(gif_b64)
    return treat.as_binary(gif_bytes, "image/gif")
end

When main result is returned, binary object content-type takes a priority over a value set by splash:set_result_content_type. To override content-type of a binary object create another binary object with a required content-type:

lcoal treat = require("treat")
function main(splash)
    -- ...
    local img = splash:png()
    return treat.as_binary(img, "image/x-png") -- default was "image/png"
end

When a binary object is serialized to JSON it is auto-encoded to base64 before serializing. For example, it may happen when a table is returned as a main function result:

function main(splash)
    assert(splash:go(splash.args.url))

    -- result is a JSON object {"png": "...base64-encoded image data"}
    return {png=splash:png()}
end

Available Lua Libraries¶

When Sandbox is disabled all standard Lua modules are available; with a Sandbox ON (default) only some of them can be used. See Standard Library for more.

Splash ships several non-standard modules by default:

json - encoded/decode JSON data
base64 - encode/decode Base64 data
treat - fine-tune the way Splash works with your Lua varaibles and returns the result.

Unlike standard modules, custom modules should to be imported before use, for example:

base64 = require("base64")
function main(splash)
    return base64.encode('hello')
end

It is possible to add more Lua libraries to Splash using Custom Lua Modules feature.

Standard Library¶

The following standard Lua 5.2 libraries are available to Splash scripts when Sandbox is enabled (default):

Aforementioned libraries are pre-imported; there is no need to require them.

Note

Not all functions from these libraries are currently exposed when Sandbox is enabled.

json¶

A library to encode data to JSON and decode it from JSON to Lua data structure. It provides 2 functions: json.encode and json.decode.

json.encode¶

Encode data to JSON.

Signature: result = json.encode(obj)

Parameters:

obj - an object to encode.

Returns: a string with JSON representation of obj.

JSON format doesn’t support binary data; json.encode handles Binary Objects by automatically encoding them to Base64 before putting to JSON.

json.decode¶

Decode JSON string to a Lua object.

Signature: decoded = json.decode(s)

Parameters:

s - a string with JSON.

Returns: decoded Lua object.

Example:

json = require("json")

function main(splash)
    local resp = splash:http_get("http:/myapi.example.com/resource.json")
    local decoded = json.decode(resp.content.text)
    return {myfield=decoded.myfield}
end

Note that unlike json.encode function, json.decode doesn’t have any special features to support binary data. It means that if you want to get a binary object encoded by json.encode back, you need to decode data from base64 yourselves. This can be done in a Lua script using base64 module.

base64¶

A library to encode/decode strings to/from Base64. It provides 2 functions: base64.encode and base64.decode. These functions are handy if you need to pass some binary data in a JSON request or response.

base64.encode¶

Encode a string or a binary object to Base64.

Signature: encoded = base64.encode(s)

Parameters:

s - a string or a binary object to encode.

Returns: a string with Base64 representation of s.

base64.decode¶

Decode a string from base64.

Signature: data = base64.decode(s)

Parameters:

s - a string to decode.

Returns: a Lua string with decoded data.

Note that base64.decode may return a non-UTF-8 Lua string, so the result may be unsafe to pass back to Splash (as a part of main function result or as an argument to splash methods). It is fine if you know the original data was ASCII or UTF8, but if you work with unknown data, “real” binary data or just non-UTF-8 content then call treat.as_binary on the result of base64.decode.

Example - return 1x1px black gif:

treat = require("treat")
base64 = require("base64")

function main(splash)
    local gif_b64 = "AQABAIAAAAAAAAAAACH5BAAAAAAALAAAAAABAAEAAAICTAEAOw=="
    local gif_bytes = base64.decode(gif_b64)
    return treat.as_binary(gif_bytes, "image/gif")
end

treat¶

treat.as_binary¶

Get a binary object for a string.

Signature: bytes = treat.as_binary(s, content_type="application/octet-stream")

Parameters:

s - a string.
content-type - Content-Type of s.

Returns: a binary object.

treat.as_binary returns a binary object for a string. This binary object no longer can be processed from Lua, but it can be returned as a main() result as-is.

treat.as_string¶

Get a Lua string with a raw data from a binary object.

Signature: s, content_type = treat.as_string(bytes)

Parameters:

bytes - a binary object.

Returns: (s, content_type) pair: a Lua string with raw data and its Content-Type.

treat.as_string “unwraps” a binary object and returns a plain Lua string which can be processed from Lua. If the resulting string is not encoded to UTF-8 then it is still possible to process it in Lua, but it is not safe to return it as a main result or pass to Splash functions. Use treat.as_binary to convert processed string to a binary object if you need to pass it back to Splash.

treat.as_array¶

Mark a Lua table as an array (for JSON encoding and Lua -> JS conversions).

Signature: tbl = treat.as_array(tbl)

Parameters:

tbl - a Lua table.

Returns: the same table.

JSON can represent arrays and objects, but in Lua there is no distinction between them; both key-value mappings and arrays are stored in Lua tables.

By default, Lua tables are converted to JSON objects when returning a result from Splash main function and when using json.encode or ref:splash-jsfunc:

function main(splash)
    -- client gets {"foo": "bar"} JSON object
    return {foo="bar"}
end

It can lead to unexpected results with array-like Lua tables:

function main(splash)
    -- client gets {"1": "foo", "2": "bar"} JSON object
    return {"foo", "bar"}
end

treat.as_array allows to mark tables as JSON arrays:

treat = require("treat")

function main(splash)
    local tbl = {"foo", "bar"}
    treat.as_array(tbl)

    -- client gets ["foo", "bar"] JSON object
    return tbl
end

This function modifies its argument inplace, but as a shortcut it returns the same table; it allows to simplify the code:

treat = require("treat")
function main(splash)
    -- client gets ["foo", "bar"] JSON object
    return treat.as_array({"foo", "bar"})
end

Note

There is no autodetection of table type because {} Lua table is ambiguous: it can be either a JSON array or as a JSON object. With table type autodetection it is easy to get a wrong output: even if some data is always an array, it can be suddenly exported as an object when an array is empty. To avoid surprises Splash requires an explicit treat.as_array call.

Adding Your Own Modules¶

Splash provides a way to use custom Lua modules (stored on server) from scripts passed via HTTP API. This allows to

reuse code without sending it over network again and again;
use third-party Lua modules;
implement features which need unsafe code and expose them safely in a sandbox.

Note

To learn about Lua modules check e.g. http://lua-users.org/wiki/ModulesTutorial. Please prefer “the new way” of writing modules because it plays better with a sandbox. A good Lua modules style guide can be found here: http://hisham.hm/2014/01/02/how-to-write-lua-modules-in-a-post-module-world/

Setting Up¶

To use custom Lua modules, do the following steps:

setup the path for Lua modules and add your modules there;
tell Splash which modules are enabled in a sandbox;
use Lua require function from a script to load a module.

To setup the path for Lua modules start Splash with --lua-package-path option. --lua-package-path value should be a semicolon-separated list of places where Lua looks for modules. Each entry should have a ? in it that’s replaced with the module name.

Example:

$ python -m splash.server --lua-package-path "/etc/splash/lua_modules/?.lua;/home/myuser/splash-modules/?.lua"

Note

If you use Splash installed using Docker see Folders Sharing for more info on how to setup paths.

Note

For the curious: --lua-package-path value is added to Lua package.path.

When you use a Lua sandbox (default) Lua require function is restricted when used in scripts: it only allows to load modules from a whitelist. This whitelist is empty by default, i.e. by default you can require nothing. To make your modules available for scripts start Splash with --lua-sandbox-allowed-modules option. It should contain a semicolon-separated list of Lua module names allowed in a sandbox:

$ python -m splash.server --lua-sandbox-allowed-modules "foo;bar" --lua-package-path "/etc/splash/lua_modules/?.lua"

After that it becomes possible to load these modules from Lua scripts using require:

local foo = require("foo")
function main(splash)
    return {result=foo.myfunc()}
end

Writing Modules¶

A basic module could look like the following:

-- mymodule.lua
local mymodule = {}

function mymodule.hello(name)
    return "Hello, " .. name
end

return mymodule

Usage in a script:

local mymodule = require("mymodule")

function main(splash)
    return mymodule.hello("world!")
end

Many real-world modules will likely want to use splash object. There are several ways to write such modules. The simplest way is to use functions that accept splash as an argument:

-- utils.lua
local utils = {}

-- wait until `condition` function returns true
function utils.wait_for(splash, condition)
    while not condition() do
        splash:wait(0.05)
    end
end

return utils

Usage:

local utils = require("utils")

function main(splash)
    splash:go(splash.args.url)

    -- wait until <h1> element is loaded
    utils.wait_for(splash, function()
       return splash:evaljs("document.querySelector('h1') != null")
    end)

    return splash:html()
end

Another way to write such module is to add a method to splash object. This can be done by adding a method to its Splash class - the approach is called “open classes” in Ruby or “monkey-patching” in Python.

-- wait_for.lua

-- Sandbox is not enforced in custom modules, so we can import
-- internal Splash class and change it - add a method.
local Splash = require("splash")

function Splash:wait_for(condition)
    while not condition() do
        self:wait(0.05)
    end
end

-- no need to return anything

Usage:

require("wait_for")

function main(splash)
    splash:go(splash.args.url)

    -- wait until <h1> element is loaded
    splash:wait_for(function()
       return splash:evaljs("document.querySelector('h1') != null")
    end)

    return splash:html()
end

Which style to prefer is up to the developer. Functions are more explicit and composable, monkey patching enables a more compact code. Either way, require is explicit.

As seen in a previous example, sandbox restrictions for standard Lua modules and functions are not applied in custom Lua modules, i.e. you can use all the Lua powers. This makes it possible to import third-party Lua modules and implement advanced features, but requires developer to be careful. For example, let’s use os module:

-- evil.lua
local os = require("os")
local evil = {}

function evil.sleep()
    -- Don't do this! It blocks the event loop and has a startup cost.
    -- splash:wait is there for a reason.
    os.execute("sleep 2")
end

function evil.touch(filename)
    -- another bad idea
    os.execute("touch " .. filename)
end

-- todo: rm -rf /

return evil

Splash and Jupyter¶

Splash provides a custom Jupyter (previously known as IPython) kernel for Lua. Together with Jupyter notebook frontend it forms an interactive web-based development environment for Splash Scripts with syntax highlighting, smart code completion, context-aware help, inline images support and a real live WebKit browser window with Web Inspector enabled, controllable from a notebook.

Installation¶

To install Splash-Jupyter using Docker, run:

$ docker pull scrapinghub/splash-jupyter

Then start the container:

$ docker run -p 8888:8888 -it scrapinghub/splash-jupyter

Note

Without -it flags you won’t be able to stop the container using Ctrl-C.

If you’re on Linux, Jupyter server with Splash kernel enabled will be available at http://0.0.0.0:8888.

If you use boot2docker, run $ boot2docker ip to get the ip address, the visit http://<ip-returned-by-boot2docker>:8888. If you use docker-machine, run $ docker-machine ip <your machine> to get the ip.

By default, notebooks are stored in a Docker container; they are destroyed when you restart an image. To persist notebooks you can mount a local folder to /notebooks. For example, let’s use current folder to store the notebooks:

$ docker run -v `/bin/pwd`/notebooks:/notebooks -p 8888:8888 -it splash-jupyter

To view Live Webkit window with web inspector when Splash-Jupyter is executed from Docker, you will need to pass additional docker parameters to share the host system’s X server with the docker container, and use the --disable-xvfb command line flag:

$ docker run -e DISPLAY=unix$DISPLAY \
             -v /tmp/.X11-unix:/tmp/.X11-unix \
             -v $XAUTHORITY:$XAUTHORITY \
             -e XAUTHORITY=$XAUTHORITY \
             -p 8888:8888 \
             -it scrapinghub/splash-jupyter --disable-xvfb

Alternatively, to enable live Webkit window you can install Splash in a “manual way” - see Ubuntu 14.04 (manual way).

Install IPython/Jupyter with notebook feature. Splash kernel requires IPython 4.x:
```
$ pip3 install 'ipython[notebook] >= 4.0.0, < 5.0'
```
Make sure Splash is installed: run pip3 install -U splash. If you use Splash master branch run pip3 install -U . from source checkout instead.
Let IPython know about Splash kernel by running the following command:
```
$ python3 -m splash.kernel install
```

To run IPython with Splash notebook, first start IPython notebook and then create a new Splash notebook using “New” button.

From Notebook to HTTP API¶

After you finished developing the script using a Jupyter Notebook, you may want to convert it to a form suitable for submitting to Splash HTTP API (see execute).

To do that, copy-paste (or download using “File -> Download as -> .lua”) all relevant code, then put it inside function main(splash):

function main(splash)
    -- Script code goes here,
    -- including all helper functions.
    return {...}  -- return the result
end

To make the script more generic you can use splash.args instead of hardcoded constants (e.g. for page urls). Also, consider submitting several requests with different arguments instead of running a loop in a script if you need to visit and process several pages - it is an easy way to parallelize the work.

There are some gotchas:

When you run a notebook cell and then run another notebook cell there is a delay between runs; the effect is similar to inserting splash:wait calls at the beginning of each cell.
Regardless of sandbox settings, scripts in Jupyter notebook are not sandboxed. Usually it is not a problem, but some functions may be unavailable in HTTP API if sandbox is enabled.

FAQ¶

I’m getting lots of 504 Timeout errors, please help!¶

HTTP 504 error means a request to Splash took more than timeout seconds to complete (30s by default) - Splash aborts script execution after the timeout. To override the timeout value pass ‘timeout’ argument to the Splash endpoint you’re using.

Note that the maximum allowed timeout value is limited by the maximum timeout setting, which is by default 60 seconds. In other words, by default you can’t pass ?timeout=300 to run a long script - an error will be returned.

Maximum allowed timeout can be increased by passing --max-timeout option to Splash server on startup:

$ python -m splash.server --max-timeout 3600

For Docker the command would be something like this (see Passing Custom Options):

$ docker run -it -p 8050:8050 scrapinghub/splash --max-timeout 3600

The next question is why a request can need 10 minutes to render. There are 3 common reasons:

1. Slow website¶

A website can be really slow, or it can try to get some remote resources which are really slow.

There is no way around increasing timeouts and reducing request rate if the website itself is slow. However, often the problem lays in unreliable remote resources like third-party trackers or advertisments. By default Splash waits for all remote resources to load, but in most cases it is better not to wait for them forever.

To abort resource loading after a timeout and give the whole page a chance to render use resource timeouts. For render.*** endpoints use ‘resource_timeout’ argument; for execute use either splash.resource_timeout or request:set_timeout (see splash:on_request).

It is a good practive to always set resource_timeout; something similar to resource_timeout=20 often works well.

2. Splash Lua script does too many things¶

When a script fetches many pages or uses large delays then timeouts are inevitable. Sometimes you have to run such scripts; in this case increase --max-timeout Splash option and use larger timeout values.

But before increasing the timeouts consider splitting your script into smaller steps and sending them to Splash individually. For example, if you need to fetch 100 websites, don’t write a Splash Lua script which takes a list of 100 URLs and fetches them - write a Splash Lua script that takes 1 URL and fetches it, and send 100 requests to Splash. This approach has a number of benefits: it makes scripts more simple and robust and enables parallel processing.

3. Splash instance is overloaded¶

When Splash is overloaded it may start producing 504 errors.

Splash renders requests in parallel, but it doesn’t render them all at the same time - concurrency is limited to a value set at startup using --slots option. When all slots are used a request is put into a queue. The thing is that a timeout starts to tick once Splash receives a request, not when Splash starts to render it. If a request stays in an internal queue for a long time it can timeout even if a website is fast and splash is capable of rendering the website.

To increase rendering speed and fix an issue with a queue it is recommended to start several Splash instances and use a load balancer capable of maintaining its own request queue. HAProxy has all necessary features; check an example config here. A shared request queue in a load balancer also helps with reliability: you won’t be loosing requests if a Splash instance needs to be restarted.

Note

Nginx (which is another popular load balancer) provides an internal queue only in its commercial version, Nginx Plus.

How to run Splash in production?¶

Easy Way¶

If you want to get started quickly take a look at Aquarium (which is a Splash setup without many of the pitfalls) or use a hosted solution like ScrapingHub’s.

Don’t forget to use resource timeous in your client code (see 1. Slow website). It also makes sense to retry a couple of times if Splash returns 5xx error response.

Hard Way¶

If you want to create your own production setup, here is a small non-exhaustive checklist:

Splash should be daemonized and started on boot;
in case of failures or segfaults Splash must be restarted;
memory usage should be limited;
several Splash instances should be started to use all CPU cores and/or multiple servers;
requests queue should be moved to the load balancer to make rendering more robust (see 3. Splash instance is overloaded).

Of course, it is also good to setup monitoring, configuration management, etc. - all the usual stuff.

To daemonize Splash, start it on boot and restart on failures one can use Docker: since Docker 1.2 there are --restart and -d options which can be used together. Another way to do that is to use standard tools like upstart, systemd or supervisor.

Note

Docker --restart option won’t work without -d.

Splash uses an unbound in-memory cache and so it will eventually consume all RAM. A workaround is to restart the process when it uses too much memory; there is Splash --maxrss option for that. You can also add Docker --memory option to the mix.

In production it is a good idea to pin Splash version - instead of scrapinghub/splash it is usually better to use something like scrapinghub/splash:2.0.

A command for starting a long-running Splash server which uses up to 4GB RAM and daemonizes & restarts itself could look like this:

$ docker run -d -p 8050:8050 --memory=4.5G --restart=always scrapinghub/splash:2.0 --maxrss 4000

You also need a load balancer; for example configs check Aquarium or an HAProxy config in Splash repository.

Splash Development¶

Contributing¶

Splash is free & open source. Development happens at github: https://github.com/scrapinghub/splash

Development Setup¶

Consult with Installation to get Splash up and running.

Install development specific dependencies with:

$ sudo apt-get install libffi-dev libssl-dev

pip install -r requirements-dev.txt

Functional Tests¶

https://secure.travis-ci.org/scrapinghub/splash.png?branch=master

Run with:

py.test --doctest-modules splash

To speedup test running install pytest-xdist Python package and run Splash tests in parallel:

py.test --doctest-modules -n4 splash

Stress tests¶

There are some stress tests that spawn its own splash server and a mock server to run tests against.

To run the stress tests:

python -m splash.tests.stress

Typical output:

$ python -m splash.tests.stress
Total requests: 1000
Concurrency   : 50
Log file      : /tmp/splash-stress-48H91h.log
........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Received/Expected (per status code or error):
  200: 500/500
  504: 200/200
  502: 300/300

Changes¶

2.0.2 (26-02-2016)¶

This is a bugfix release:

an issue which may cause segfaults is fixed.

2.0.1 (25-02-2016)¶

This is a bugfix release:

XSS in HTTP UI is fixed;
Splash-Jupyter docker image is fixed.

2.0 (21-02-2016)¶

Splash 2.0 uses Qt 5.5.1 instead of Qt 4; it means the rendering engine now supports more HTML5 features and is more modern overall. Also, the official Docker image now uses Python 3 instead of Python 2. This work is largely done by Tarashish Mishra as a Google Summer of Code 2015 project.

Splash 2.0 release introduces other cool new features:

many Splash HTTP UI improvements;
better support for binary data;
built-in json and base64 libraries;
more control for result serialization (support for JSON arrays and raw bytes);
it is now possible to turn Private mode OFF at startup using command-line option or at runtime using splash.private_mode_enabled attribute;
_ping endpoint is added;
cookie handling is fixed;
downloader efficiency is improved;
request processing is stopped when client disconnects;
logging inside callbacks now uses proper verbosity;
sandbox memory limit for user objects is increased to 50MB;
some sandboxing issues are fixed;
splash:evaljs and splash:jsfunc results are sanitized better;
it is possible to pass arguments when starting Splash-Jupyter - it means now you can get a browser window for splash-jupyter when it is executed from docker;
proxy authentication is fixed;
logging improvements: logs now contain request arguments in JSON format; errors are logged;

There are backwards-incompatible changes to Splash Scripting: previously, different Splash methods were returning/receiving inconsistent response and request objects. For example, splash:http_get response was not in the same format as response received by splash:on_response callbacks. Splash 2.0 uses Request and Response objects consistently. Unfortunately this requires changes to existing user scripts:

replace resp = splash:http_get(...) and resp = splash:http_post(...) with resp = splash:http_get(...).info and resp = splash:http_post(...).info. Client code also may need to be changed: the default encoding of info['content']['text'] is now base64. If you used resp.content.text consider switching to response.body.
response object received by splash:on_response_headers and splash:on_response callbacks is changed: instead of response.request write response.request.info.

Serialization of JS objects in splash:jsfunc, splash:evaljs and splash:wait_for_resume is changed: circular objects are no longer returned, Splash doesn’t try to serialize DOM elements, and error messages are changed.

Splash no longer supports QT-based disk cache; it was disable by default and it usage was discouraged since Splash 1.0, in Splash 2.0 --cache command-line option is removed. For HTTP cache there are better options like Squid.

Another backwards-incompatible change is that Splash-as-a-proxy feature is removed. Please use regular HTTP API instead of this proxy interface. Of course, Splash will still support using proxies to make requests, these are two different features.

1.8 (2015-09-29)¶

New features:

POST requests support: http_method and body arguments for render endpoints; new splash:go arguments: body, http_method and formdata; new splash:http_post method.
Errors are now returned in JSON format; error mesages became more detailed; Splash UI now displays detailed error information.
new splash:call_later method which allows to schedule tasks in future;
new splash:on_response method allows to register a callback to be executed after each response;
proxy can now be set directly, without using proxy profiles - there is a new proxy argument for render endpoints;
more detailed splash:go errors: a new “render_error” error type can be reported;
new splash:set_result_status_code method;
new splash.resource_timeout attribute as a shortcut for request:set_timeout in splash:on_request;
new splash:get_version method;
new splash:autoload_reset, splash:on_response_reset, splash:on_request_reset, splash:on_response_headers_reset, splash:har_reset methods and a new reset=true argument for splash:har. They are most useful with Splash-Jupyter.

Bug fixes and improvements:

fixed an issue: proxies were not applied for POST requests;
improved argument validation for various methods;
more detailed logs;
it is now possible to load a combatibility shim for window.localStorage;
code coverage integration;
improved Splash-Jupyter tests;
Splash-Jupyter is upgraded to Jupyter 4.0.

1.7 (2015-08-06)¶

New features:

render.jpeg endpoint and splash:jpeg function allow to take screenshots in JPEG format;
splash:on_response_headers Lua function and allowed_content_types / forbidden_content_types HTTP arguments allow to discard responses earlier based on their headers;
splash.images_enabled attribute to enable/disable images from Lua scripts;
splash.js_enabled attribute to enable/disable JS processing from Lua scripts;
splash:set_result_header method for setting custom HTTP headers returned to Splash clients;
resource_timeout argument for setting network request timeouts in render endpoints;
request:set_timeout(timeout) method (ses splash:on_request) for setting request timeouts from Lua scripts;
SOCKS5 proxy support: new ‘type’ argument in proxy profile config files and request:set_proxy method (ses splash:on_request)
enabled HTTPS proxying;

Other changes:

HTTP error detection is improved;
MS fonts are added to the Docker image for better rendering quality;
Chinese fonts are added to the Docker image to enable rendering of Chinese websites;
validation of timeout and wait arguments is improved;
documentation: grammar is fixed in the tutorial;
assorted documentation improvements and code cleanups;
splash:set_images_enabled method is deprecated.

1.6 (2015-05-15)¶

The main new feature in Splash 1.6 is splash:on_request function which allows to process individual outgoing requests: log, abort, change them.

Other improvements:

a new _gc endpoint which allows to clear QWebKit caches;
Docker images are updated with more recent package versions;
HTTP arguments validation is improved;
serving Splash UI under HTTPS is fixed.
documentation improvements and typo fixes.

1.5 (2015-03-03)¶

In this release we introduce Splash-Jupyter - a web-based IDE for Splash Lua scripts with syntax highlighting, autocompletion and a connected live browser window. It is implemented as a kernel for Jupyter (IPython).

Docker images for Splash 1.5 are optimized - download size is much smaller than in previous releases.

Other changes:

splash:go() returned incorrect result after an unsuccessful splash:go() call - this is fixed;
Lua main function can now return multiple results;
there are testing improvements and internal cleanups.

1.4 (2015-02-10)¶

This release provides faster and more robust screenshot rendering, many improvements in Splash scripting engine and other improvements like better cookie handling.

From version 1.4 Splash requires Pillow (built with PNG support) to work.

There are backwards-incompatible changes in Splash scripts:

splash:set_viewport() is split into splash:set_viewport_size() and splash:set_viewport_full();
old splash:runjs() method is renamed to splash:evaljs();
new splash:runjs method just runs JavaScript code without returning the result of the last JS statement.

To upgrade check all splash:runjs() usages: if the returned result is used then replace splash:runjs() with splash:evaljs().

viewport=full argument is deprecated; use render_all=1.

New scripting features:

it is now possible to write custom Lua plugins stored server-side;
a restricted version of Lua require is enabled in sandbox;
splash:autoload() method for setting JS to load on each request;
splash:wait_for_resume() method for interacting with async JS code;
splash:lock_navigation() and splash:unlock_navigation() methods;
splash:set_viewport() is split into splash:set_viewport_size() and splash:set_viewport_full();
splash:get_viewport_size() method;
splash:http_get() method for sending HTTP GET requests without loading result to the browser;
splash:set_content() method for setting page content from a string;
splash:get_cookies(), splash:add_cookie(), splash:clear_cookies(), splash:delete_cookies() and splash:init_cookies() methods for working with cookies;
splash:set_user_agent() method for setting User-Agent header;
splash:set_custom_headers() method for setting other HTTP headers;
splash:url() method for getting current URL;
splash:go() now accepts headers argument;
splash:evaljs() method, which is a splash:runjs() from Splash v1.3.1 with improved error handling (it raises an error in case of JavaScript exceptions);
splash:runjs() method no longer returns the result of last computation;
splash:runjs() method handles JavaScript errors by returning ok, error pair;
splash:get_perf_stats() method for getting Splash resource usage.

Other improvements:

–max-timeout option can be passed to Splash at startup to increase or decrease maximum allowed timeout value;
cookies are no longer shared between requests;
PNG rendering becomes more efficient: less CPU is spent on compression. The downside is that the returned PNG images become 10-15% larger;
there is an option (scale_method=vector) to resize images while painting to avoid pixel-based resize step - it can make taking a screenshot much faster on image-light webpages (up to several times faster);
when ‘height’ is set and image is downscaled the rendering is more efficient because Splash now avoids rendering unnecessary parts;
/debug endpoint tracks more objects;
testing setup improvements;
application/json POST requests handle invalid JSON better;
undocumented splash:go_and_wait() and splash:_wait_restart_on_redirects() methods are removed (they are moved to tests);
Lua sandbox is cleaned up;
long log messages from Lua are truncated in logs;
more detailed error info is logged;
example script in Splash UI is simplified;
stress tests now include PNG rendering benchmark.

Bug fixes:

default viewport size and window geometry are now set to 1024x768; this fixes PNG screenshots with viewport=full;
PNG rendering is fixed for huge viewports;
splash:go() argument validation is improved;
timer is properly deleted when an exception is raised in an errback;
redirects handling for baseurl requests is fixed;
reply is deleted only once when baseurl is used.

1.3.1 (2014-12-13)¶

This release fixes packaging issues with Splash 1.3.

1.3 (2014-12-04)¶

This release introduces an experimental scripting support.

Other changes:

manhole is disabled by default in Debian package;
more objects are tracked in /debug endpoint;
“history” in render.json now includes “queryString” keys; it makes the output compatible with HAR entry format;
logging improvements;
improved timer cancellation.

1.2.1 (2014-10-16)¶

Dockerfile base image is downgraded to Ubuntu 12.04 to fix random crashes;
Debian/buildbot config is fixed to make Splash UI available when deployed from deb;
Qt / PyQt / sip / WebKit / Twisted version numbers are logged at startup.

1.2 (2014-10-14)¶

All Splash rendering endpoints now accept Content-Type: application/json POST requests with JSON-encoded rendering options as an alternative to using GET parameters;
headers parameter allows to set HTTP headers (including user-agent) for all endpoints - previously it was possible only in proxy mode;
js_source parameter allows to execute JS in page context without application/javascript POST requests;
testing suite is switched to pytest, test running can now be parallelized;
viewport size changes are logged;
/debug endpoint provides leak info for more classes;
Content-Type header parsing is less strict;
documentation improvements;
various internal code cleanups.

1.1 (2014-10-10)¶

An UI is added - it allows to quickly check Splash features.
Splash can now return requests/responses information in HAR format. See render.har endpoint and har argument of render.json endpoint. A simpler history argument is also available. With HAR support it is possible to get timings for various events, HTTP status code of the responses, HTTP headers, redirect chains, etc.
Processing of related resources is stopped earlier and more robustly in case of timeouts.
wait parameter changed its meaning: waiting now restarts after each redirect.
Dockerfile is improved: image is updated to Ubuntu 14.04; logs are shown immediately; it becomes possible to pass additional options to Splash and customize proxy/js/filter profiles; adblock filters are supported in Docker; versions of Python dependencies are pinned; Splash is started directly (without supervisord).
Splash now tries to start Xvfb automatically - no need for xvfb-run. This feature requires xvfbwrapper Python package to be installed.
Debian package improvements: Xvfb viewport matches default Splash viewport, it is possible to change Splash option using SPLASH_OPTS environment variable.
Documentation is improved: finally, there are some install instructions.
Logging: verbosity level of several logging events are changed; data-uris are truncated in logs.
Various cleanups and testing improvements.

1.0 (2014-07-28)¶

Initial release.

Splash - A javascript rendering service¶

Documentation¶

Installation¶

Linux + Docker¶

OS X + Docker¶

Ubuntu 14.04 (manual way)¶

Required Python packages¶

Splash Versions¶

Customizing Dockerized Splash¶

Passing Custom Options¶

Folders Sharing¶

Building Local Docker Images¶

Splash HTTP API¶

render.html¶

Examples¶

render.png¶

Examples¶

render.jpeg¶

Examples¶

render.har¶

render.json¶

Examples¶

execute¶

Executing custom Javascript code within page context¶

Javascript Profiles¶

Javascript Security¶

Request Filters¶

Proxy Profiles¶

Other Endpoints¶

_gc¶

_debug¶

_ping¶

Splash Scripts Tutorial¶

Intro¶

Entry Point: the “main” Function¶

Where Are My Callbacks?¶

Living Without Callbacks¶

Calling Splash Methods¶

Error Handling¶

Sandbox¶

Timeouts¶

Splash Scripts Reference¶

Attributes¶

splash.args¶

splash.js_enabled¶

splash.private_mode_enabled¶

splash.resource_timeout¶

splash.images_enabled¶

Methods¶

splash:go¶

splash:wait¶

splash:jsfunc¶

splash:evaljs¶

splash:runjs¶

splash:wait_for_resume¶

splash:autoload¶

splash:autoload_reset¶

splash:call_later¶

splash:http_get¶

splash:http_post¶

splash:set_content¶

splash:html¶

splash:png¶

splash:jpeg¶

splash:har¶

splash:har_reset¶

splash:history¶

splash:url¶

splash:get_cookies¶

splash:add_cookie¶

splash:init_cookies¶

splash:clear_cookies¶

splash:delete_cookies¶

splash:lock_navigation¶

splash:unlock_navigation¶

splash:set_result_status_code¶

splash:set_result_content_type¶

splash:set_result_header¶

splash:get_viewport_size¶

splash:set_viewport_size¶