Frontend Prerenderer

Uses PhantomJS/Chromium to render a single-page application written in javascript. Useful for SEO and indexing by social media. Works on LOW-END-BOXES, does not consume much ram memory.

/*
 * Wolnościowiec / Frontend Pre-renderer
 * -------------------------------------
 *
 *   Wolnościowiec is a project to integrate the movement
 *   of people who strive to build a society based on
 *   solidarity, freedom, equality with a respect for
 *   individual and cooperation of each other.
 *
 *   We support human rights, animal rights, feminism,
 *   anti-capitalism (taking over the production by workers),
 *   anti-racism, and internationalism. We negate
 *   the political fight and politicians at all.
 *
 *   http://wolnosciowiec.net/en
 *
 *   License: LGPLv3
 */

Configuration

Create your config.php file in the root directory to override default settings. The config.dist.php is a default configuration file and can be copied in place of config.php

Reference

• skipped_headers: List of headers to not forward (PhantomJS only)
• allowed_domains: Accept requests only for those domains (all browsers)
• delay: Give the browser X seconds before getting the result from it (PhantomJS only)
• timeout: Give the browser maximum amount of time to render (PhantomJS only)
• with_images: Allow to render images? Mostly its not necessary (all browsers)
• debug: Print debugging information instead of the result (PhantomJS only)
• renderer: Decides if we want to use phantomjs or chromium
• chromium_binary: The command name for Chromium, could be eg. chrome, chromium, google-chrome-beta or some path
• window_size: Browser window size (Chromium only)
• open_process_limit: Limit the amount of workers, so the server will not blow up (Chromium only)
• wait_for_process_time: Amount of seconds to wait for a process when the maximum of opened browsers (defined in open_process_limit) is reached After this time there will be a 503 returned.

Installation

make deploy

Browser differences

Feature	Chromium	PhantomJS
Response body	Fast fetch, waits for everything	Based on delay or timeout
Response headers	Not supported	Supported with exclusion list
Response code	Not supported	Supported
Requirements	Just the Chromium browser	The PhantomJS, and the NodeJS
Proxy support	Yes	No

Usage

The usage is simple, just redirect any request to this service, it should go through index.php Use the webserver to redirect requests properly and validate which domains are allowed.

Render a different page than the request

You can render any page eg. facebook.com by providing the URL in the header.

Example request:

GET /

X-Render-Url: https://www.facebook.com/events/209461189653825/

This allows to use the prerender service for scrapping any pages in a microservice architecture, with scaled services behind the load balancer.

Cache regeneration

The service keeps the history of successful requests from robots, so later there is a possibility to click all of those links again using a script reclick-cache

To pass the clicks from reclick-cache you have to redirect it's useragent curl/reclick-cache through the prerenderer, so accept it as a crawler on the webserver configuration just like you do for search engines.

Schedule ./bin/reclick-cache.sh to run eg. daily to regenerate the cache, so the crawlers could hit the cached version instead of waiting long for the page to load.

Proxy support

(Works only in Chromium)

By passing a header "X-Proxy-Address" you can enforce the browser to use a proxy server.

Example:

X-Proxy-Address: http://localhost:8080