Azure Storage

A custom storage system for Django using Windows Azure Storage backend.

Notes

Be aware Azure file names have some extra restrictions. They can’t:

  • end with dot (.) or slash (/)
  • contain more than 256 slashes (/)
  • be longer than 1024 characters

This is usually not an issue, since some file-systems won’t allow this anyway. There’s default_storage.get_name_max_len() method to get the max_length allowed. This is useful for form inputs. It usually returns 1024 - len(azure_location_setting). There’s default_storage.get_valid_name(...) method to clean up file names when migrating to Azure.

Gzipping for static files must be done through Azure CDN.

Install

Install Azure SDK:

pip install django-storages[azure]

Private VS Public Access

The AzureStorage allows a single container. The container may have either public access or private access. When dealing with a private container, the AZURE_URL_EXPIRATION_SECS must be set to get temporary URLs.

A common setup is having private media files and public static files, since public files allow for better caching (i.e: no query-string within the URL).

One way to support this is having two backends, a regular AzureStorage with the private container and expiration setting set, and a custom backend (i.e: a subclass of AzureStorage) for the public container.

Custom backend:

# file: ./custom_storage/custom_azure.py
class PublicAzureStorage(AzureStorage):
    account_name = 'myaccount'
    account_key = 'mykey'
    azure_container = 'mypublic_container'
    expiration_secs = None

Then on settings set:

DEFAULT_FILE_STORAGE = 'storages.backends.azure_storage.AzureStorage'
STATICFILES_STORAGE = 'custom_storage.custom_azure.PublicAzureStorage'

Settings

The following settings should be set within the standard django configuration file, usually settings.py.

Set the default storage (i.e: for media files) and the static storage (i.e: fo static files) to use the azure backend:

DEFAULT_FILE_STORAGE = 'storages.backends.azure_storage.AzureStorage'
STATICFILES_STORAGE = 'storages.backends.azure_storage.AzureStorage'

The following settings are available:

is_emulated = setting(‘AZURE_EMULATED_MODE’, False)

AZURE_ACCOUNT_NAME

This setting is the Windows Azure Storage Account name, which in many cases is also the first part of the url for instance: http://azure_account_name.blob.core.windows.net/ would mean:

AZURE_ACCOUNT_NAME = "azure_account_name"

AZURE_ACCOUNT_KEY

This is the private key that gives Django access to the Windows Azure Account.

AZURE_CONTAINER

This is where the files uploaded through Django will be uploaded. The container must be already created, since the storage system will not attempt to create it.

AZURE_SSL

Set a secure connection (HTTPS), otherwise it’s makes an insecure connection (HTTP). Default is True

AZURE_UPLOAD_MAX_CONN

Number of connections to make when uploading a single file. Default is 2

AZURE_CONNECTION_TIMEOUT_SECS

Global connection timeout in seconds. Default is 20

AZURE_BLOB_MAX_MEMORY_SIZE

Maximum memory used by a downloaded file before dumping it to disk. Unit is in bytes. Default is 2MB

AZURE_URL_EXPIRATION_SECS

Seconds before a URL expires, set to None to never expire it. Be aware the container must have public read permissions in order to access a URL without expiration date. Default is None

AZURE_OVERWRITE_FILES

Overwrite an existing file when it has the same name as the file being uploaded. Otherwise, rename it. Default is False

AZURE_LOCATION

Default location for the uploaded files. This is a path that gets prepended to every file name.