atilla / thumbsup

Simple Website screenshot service based on PhantomJS and Tornado

About Thumbsup

Thumbsup is a simple website screenshot service.

It uses the excellent http://phantomjs.org/ from Ariya Hidayat to render websites to image files.

This projects embeds the 'urlnorm' URL normalisation routine, written in Python by Mark Nottingham.

It requires ImageMagick for the image manipulation routines.

Thumbsup is built as a web-service using Tornado async web server. Most of the code deals with spawning phantomjs and imagemagic processes for getting the images and collecting the output of the external calls.

The images are served as static files and are cached - once generated, a screenshot will persist until the file is removed. You can easily use another web server for the static file handling, or just put Thumbsup behind a Varnish proxy.

Cache invalidation is easily done with a simple cron job that wipes all files older than your cache period.

File Storage

You can choose between two ways to store your files.

• All in one folder, filename being the hash of the URL and render sizes
• Slightly more elaborate two-level folder scheme, in order to fit a large number of files.

The first file storage methodology is quite naive and will not scale with big amounts of files for obvious reasons. The service will automatically use the second storage scheme, if it detects more than two subfolders in the static files folder. Don't forget you will need the right permissions for the destination folder.

Usage

Simply make a GET request to the specified port. The only required parameter is host which is the URL of the page you want to render.

Optionally you can specify the viewport size view_size, to which the image will be rendered and cropped and thumb_size which are the dimensions to which the rendered screenshot will be resized to. By default those values are '1280x1024' and '320x200', respectively.

Current flaws

Obviously, the service in its current form is a gigantic forkbomb :) One can easily fire off enough requests to kill it, as Tornado will do a pretty good job of spawning things until the system blocks. If you are running thumbsup behind a reverse proxy of some sort, I would strongly advise you to make good use of its rate-limiting. Most of them have some sort of rate-limiting mechanism.

You can keep a pretty large number of files, as long as you create a good number of subfolders in your storage location, but you need to do this manually and the service needs to be restarted.