Remote Storages

In some cases it’s useful to use a CDN for serving static files such as those generated by Django Compressor. Due to the way Django Compressor processes files, it requires the files to be processed (in the {% compress %} block) to be available in a local file system cache.

Django Compressor provides hooks to automatically have compressed files pushed to a remote storage backend. Simply set the storage backend that saves the result to a remote service (see COMPRESS_STORAGE).

django-storages

So assuming your CDN is Amazon S3, you can use the boto3 storage backend from the 3rd party app django-storages. Some required settings are:

AWS_ACCESS_KEY_ID = 'XXXXXXXXXXXXXXXXXXXXX'
AWS_SECRET_ACCESS_KEY = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
AWS_STORAGE_BUCKET_NAME = 'compressor-test'

Next, you need to specify the new CDN base URL and update the URLs to the files in your templates which you want to compress:

COMPRESS_URL = "http://compressor-test.s3.amazonaws.com/"

Note

For staticfiles just set STATIC_URL = COMPRESS_URL

The storage backend to save the compressed files needs to be changed, too:

COMPRESS_STORAGE = 'storages.backends.s3boto3.S3Boto3Storage'

Using staticfiles

If you are using Django’s staticfiles contrib app, you’ll need to use a temporary filesystem cache for Django Compressor to know which files to compress. Since staticfiles provides a management command to collect static files from various locations which uses a storage backend, this is where both apps can be integrated.

1. Make sure the COMPRESS_ROOT and STATIC_ROOT settings are equal since both apps need to look at the same directories when doing their job.

2. You need to create a subclass of the remote storage backend you want to use; below is an example of the boto3 S3 storage backend from django-storages:

   from django.core.files.storage import storages
   from storages.backends.s3boto3 import S3Boto3Storage
   
   class CachedS3Boto3Storage(S3Boto3Storage):
       """
       S3 storage backend that saves the files locally, too.
       """
       def __init__(self, *args, **kwargs):
           super().__init__(*args, **kwargs)
           self.local_storage = storages.create_storage({
               "BACKEND": "compressor.storage.CompressorFileStorage"
           })
   
       def save(self, name, content):
           self.local_storage.save(name, content)
           super().save(name, self.local_storage._open(name))
           return name
   

3. Set your COMPRESS_STORAGE, STATICFILES_STORAGE and COMPRESS_OFFLINE_MANIFEST_STORAGE settings to the dotted path of your custom cached storage backend, e.g. 'mysite.storage.CachedS3Boto3Storage'.

4. To have Django correctly render the URLs to your static files, set the STATIC_URL setting to the same value as COMPRESS_URL (e.g. "http://compressor-test.s3.amazonaws.com/").

In the end it might look like this:

STATIC_ROOT = '/path/to/staticfiles'
COMPRESS_ROOT = STATIC_ROOT
STATICFILES_STORAGE = 'mysite.storage.CachedS3BotoStorage'
COMPRESS_STORAGE = STATICFILES_STORAGE
COMPRESS_OFFLINE_MANIFEST_STORAGE = STATICFILES_STORAGE
STATIC_URL = 'https://compressor-test.s3.amazonaws.com/'
COMPRESS_URL = STATIC_URL