Prerender Service
Google, Facebook, Twitter, Yahoo, and Bing are constantly trying to view your website... but they don't execute javascript. That's why we built Prerender. Prerender is perfect for AngularJS SEO, BackboneJS SEO, EmberJS SEO, and any other javascript framework.
Behind the scenes, Prerender is a node server from prerender.io that uses phantomjs to create static HTML out of a javascript page. We host this as a service at prerender.io but we also open sourced it because we believe basic SEO is a right, not a privilege!
It should be used in conjunction with these middleware libraries to serve the prerendered HTML to crawlers for SEO. Get started in two lines of code using Rails or Node.
Prerender adheres to google's _escaped_fragment_ proposal, which we recommend you use. It's easy:
- Just add <meta name="fragment" content="!"> to the <head> of all of your pages
- If you use hash urls (#), change them to the hash-bang (#!)
- That's it! Perfect SEO on javascript pages.
Prerender includes lots of plugins, for example using Amazon S3 to cache your prerendered HTML.
Prerender also starts multiple phantomjs processes to maximize throughput.
Middleware
This is a list of middleware available to use with the prerender service:
Official middleware
Javascript
- prerender-node (Express)
Ruby
- prerender_rails (Rails)
Apache
Nginx
Community middleware
PHP
- zfr-prerender (Zend Framework 2)
- YuccaPrerenderBundle (Symfony 2)
Java
Grails
Nginx
Apache
Request more middleware for a different framework in this issue.
How it works
This is a simple service that only takes a url and returns the rendered HTML (with all script tags removed).
Note: you should proxy the request through your server (using middleware) so that any relative links to CSS/images/etc still work.
GET http://service.prerender.io/https://google.com
GET http://service.prerender.io/https://google.com/search?q=angular
Running locally
If you are trying to test Prerender with your website on localhost, you'll have to run the Prerender server locally so that Prerender can access your local dev website.
If you are running the prerender service locally. Make sure you set your middleware to point to your local Prerender server with:
export PRERENDER_SERVICE_URL=<your local url>
$ npm install
$ node server.js
// also supports heroku style invocation using foreman
$ foreman start
Deploying your own on heroku
$ git clone https://github.com/prerender/prerender.git
$ heroku create
$ git push heroku master
Customization
See prerender.io/server to see how to customize the server.
You can clone this repo and run server.js
OR
use npm install prerender --save to create an express-like server with custom plugins
Plugins
See prerender.io/server to see how to create plugins.
We use a plugin system in the same way that Connect and Express use middleware. Our plugins are a little different and we don't want to confuse the prerender plugins with the prerender middleware, so we opted to call them "plugins".
Plugins are in the lib/plugins directory, and add functionality to the prerender service.
Each plugin can implement any of the plugin methods:
init()
beforePhantomRequest(req, res, next)
onPhantomPageCreate(page, context, next)
afterPhantomRequest(page, context, next)
beforeSend(req, res, next)
Available plugins
removeScriptTags
We remove script tags because we don't want any framework specific routing/rendering to happen on the rendered HTML once it's executed by the crawler. The crawlers may not execute javascript, but we'd rather be safe than have something get screwed up.
For example, if you rendered the HTML of an angular page but left the angular scripts in there, your browser would try to execute the angular routing and rendering on a page that no longer has any angular bindings.
httpHeaders
If your Javascript routing has a catch-all for things like 404's, you can tell the prerender service to serve a 404 to google instead of a 200. This way, google won't index your 404's.
Add these tags in the <head> of your page if you want to serve soft http headers. Note: Prerender will still send the HTML of the page. This just modifies the status code and headers being sent.
Example: telling prerender to server this page as a 404
Example: telling prerender to serve this page as a 302 redirect
whitelist
If you only want to allow requests to a certain domain, use this plugin to cause a 404 for any other domains.
You can add the whitelisted domains to the plugin itself, or use the ALLOWED_DOMAINS environment variable.
export ALLOWED_DOMAINS=www.prerender.io,prerender.io
blacklist
If you want to disallow requests to a certain domain, use this plugin to cause a 404 for the domains.
You can add the blacklisted domains to the plugin itself, or use the BLACKLISTED_DOMAINS environment variable.
export BLACKLISTED_DOMAINS=yahoo.com,www.google.com
s3HtmlCache
A GET request will check S3 for a cached copy. If a cached copy is found, it will return that. Otherwise, it will make the request to your server and then persist the HTML to the S3 cache.
A POST request will skip the S3 cache. It will make a request to your server and then persist the HTML to the S3 cache. The POST is meant to update the cache.
You'll need to sign up with Amazon Web Services and export these 3 environment variables.
$ export AWS_ACCESS_KEY_ID=<aws access key>
$ export AWS_SECRET_ACCESS_KEY=<aws secret access key>
$ export S3_BUCKET_NAME=<bucket name>
Warning! Your keys should be kept private and you'll be charged for all files uploaded to S3.
If Prerender is hosted on a EC2 instance, you can also take advantage of IAM instance roles so that you don't need to export your AWS credentials.
You can also export the S3_PREFIX_KEY variable so that the key (which is by default the complete requested URL) is prefixed. This is useful if you want to organize the snapshots in the same bucket.
inMemoryHtmlCache
The default is an in memory cache but you can easily change it to any caching system compatible with the cache-manager nodejs package.
For example, with the request:
GET http://service.prerender.io/https://facebook.com
First time: Overall Elapsed: 00:00:03.3174661
With cache: Overall Elapsed: 00:00:00.0360119
logger
This will show console.log's from the phantomjs page in your local console. Great for debugging.
License
The MIT License (MIT)
Copyright (c) 2013 Todd Hooper <todd@prerender.io>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.