django-s3-cache 0.4

Amazon Simple Storage Service (S3) cache backend for Django

About

This is Amazon Simple Storage Service (S3) cache backend for Django. It is based on the django.core.cache.backends.filebased.FileBasedCache backend and operates in similar fashion. This backend uses django-storages to read/write the data into S3. It uses the s3boto storage backend.

All key/values passed to this backend are stored in a flat directory structure in your S3 bucket. It uses sha1 instead of md5 to create the file name because it proved to be faster when I measured it.

Installation

Use pip to install from PyPI:

pip install django-s3-cache

Configure the use of this backend:

CACHES = {
    'default': {
        'BACKEND': 's3cache.AmazonS3Cache',
        'OPTIONS': {
            'ACCESS_KEY_ID': 'Your AWS access key',
            'SECRET_ACCESS_KEY' : 'Your AWS secret access key',
            'STORAGE_BUCKET_NAME': 'Your AWS storage bucket name',
        }
    }
}

Configuration

Django S3 Cache supports many configuration options. They should be defined as keys of the OPTIONS dictionary in settings.py as shown abowe. For a full list take a look at the code. If something is not defined explicitly it follows the defaults of s3boto backend from django-storages which in turn reads them from settings.py.

NB: some values in settings.py may be used globally by boto and other AWS aware Django components since they follow the format AWS_XXXX. It’s always best to define your values as cache options explicitly if you don’t want to run into problems.

Some notable options are:

• LOCATION - the directory prefix under which to store cache files. Defaults to empty string, which means the root directory;

• DEFAULT_ACL == private - default ACL for created objects. Unlike the s3boto storage backend we set this to private;

• BUCKET_ACL == DEFAULT_ACL - ACL for the bucket if auto created. By default set to private. It’s best to use separate bucket for cache files;

• REDUCED_REDUNDANCY - set to True if you want to save a few cents on storage costs;

• IS_GZIPPED - set to True to enable Gzip compression. Used together with GZIP_CONTENT_TYPES. See django-storages documentation.

Django S3 implements culling strategy similar to the stock filesystem backend. It will honor the following options:

• MAX_ENTRIES - the maximum number of entries allowed in the cache before old values are deleted. This argument defaults to 300;

• CULL_FREQUENCY - the fraction of entries that are culled when MAX_ENTRIES is reached. The actual ratio is 1/CULL_FREQUENCY, so set CULL_FREQUENCY to 2 to cull half of the entries when MAX_ENTRIES is reached;

Contibuting

Source code and issue tracker are at https://github.com/atodorov/django-s3-cache