imageproxy is a small standalone WSGI application that dynamically resizes images.

It supports virtual hosting, so you can use the same instance to serve assets for different domains.

Example config file:

[site:example.net]
root=/srv/example.net/web/media/images
prefix=/assets/media/images

[site:example.com]
root=/srv/example.com/web/media/images
prefix=/assets/media/images

By default only JPEG files can be resized, but if you'd like to make GIFs and PNGs resizable, add the following:

[type:image/gif]
resize=true

[type:image/png]
resize=true

You can specify the configuration file location by giving its path in the IMAGEPROXY_SETTINGS environment variable.

If you want to use this with Paste, it comes with a sample config file. Naturally, you'll need Paste, PasteDeploy, and PasteScript to run it. However, Paste isn't required and the imageproxy.create_application callable can be used with any WSGI server.