This is a Python Paste middleware for OpenStack Swift. It is meant to scale down images served through Swift. For this purpose, it is using the PythonMagick Python binding for the ImageMagick Library.
Install this middleware by running the following command from the source’s base directory.
# python setup.py install
This middleware needs to be added to the proxy-server pipeline. Just add it right before the proxy-server application.
... [pipeline:main] pipeline = healthcheck authtoken keystoneauth image-scaler proxy-server [filter:image-scaler] use = egg:swift-image-scaler#image_scaler_filter maxsize = 20971520 formats = jpg;png;gif ...
We have introduced some safe guards in order to protect the hosting swift-proxy server from abuse and malfunction.
As a first measure, the feature must be enabled per container. In
order to do this, you need to set metadata on the container. Set
image-scaling to "true" (case insensitive) or "1" to enable the
feature. Using the following example, you would enable image scaling
on the image-scaling-test container. The other attributes below can be
set analogously.
$ swift post -m 'image-scaling: True' image-scaling-test
Secondly, the image object has to have an allowed extension, which can
be set as image-scaling-extensions. Just add a comma-separated list
of extensions without "." or spaces. Thus, swift stat should display
something like this.
Meta Image-Scaling-Extensions: png,JPG
The extensions are case insensitive, so "PNG" or "jpg" would be valid, too. The default set of extensions includes "jpg", "png", "gif".
As a last measure, only objects less than image-scaling-max-size will
be considered. The default value for this is 20971520 (20MB).