# Azure Storage

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

## Installation

Install Azure SDK:

    pip install django-storages[azure]

## Configuration & Settings

Django 4.2 changed the way file storage objects are configured. In particular, it made it easier to independently configure storage backends and add additional ones. To configure multiple storage objects pre Django 4.2 required subclassing the backend because the settings were global, now you pass them under the key `OPTIONS`. For example, to save media files to Azure on Django >= 4.2 you’d define:

    STORAGES = {
        "default": {
            "BACKEND": "storages.backends.azure_storage.AzureStorage",
            "OPTIONS": {
              ...your_options_here
            },
        },
    }

On Django < 4.2 you’d instead define:

    DEFAULT_FILE_STORAGE = "storages.backends.azure_storage.AzureStorage"

To put static files on Azure via `collectstatic` on Django >= 4.2 you’d include the `staticfiles` key (at the same level as `default`) in the `STORAGES` dictionary while on Django < 4.2 you’d instead define:

    STATICFILES_STORAGE = "storages.backends.azure_storage.AzureStorage"

The settings documented in the following sections include both the key for `OPTIONS` (and subclassing) as well as the global value. Given the significant improvements provided by the new API, migration is strongly encouraged.

### Authentication Settings

Several different methods of authentication are provided. In order of precedence they are:

1. `connection_string` or `AZURE_CONNECTION_STRING` (see Connection string docs)

2. (`account_key` or `AZURE_ACCOUNT_KEY`) and (`account_name` or `AZURE_ACCOUNT_NAME`)

3. `token_credential` or `AZURE_TOKEN_CREDENTIAL`

4. `sas_token` or `AZURE_SAS_TOKEN`

### Settings

`azure_container` or `AZURE_CONTAINER`

> Required

> 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` or `AZURE_SSL`

> Default: `True`

> Set a secure connection (HTTPS), otherwise it makes an insecure connection (HTTP).

`upload_max_conn` or `AZURE_UPLOAD_MAX_CONN`

> Default: `2`

> Number of connections to make when uploading a single file.

`timeout` or `AZURE_CONNECTION_TIMEOUT_SECS`

> Default: `20`

> Global connection timeout in seconds.

`max_memory` size `AZURE_BLOB_MAX_MEMORY_SIZE`

> Default: `2*1024*1024` i.e `2MB`

> Maximum memory used by a downloaded file before dumping it to disk in bytes.

`expiration_secs` or `AZURE_URL_EXPIRATION_SECS`

> Default: `None`

> 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.

`overwrite_files` or `AZURE_OVERWRITE_FILES`

> Default: `False`

> Whether or not to overwrite a file previously uploaded with the same name. If not, random character are appended.

`location` or `AZURE_LOCATION`

> Default: `''`

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

`endpoint_suffix` or `AZURE_ENDPOINT_SUFFIX`

> Default: `core.windows.net`

> Use `core.chinacloudapi.cn` for azure.cn accounts.

`custom_domain` or `AZURE_CUSTOM_DOMAIN`

> Default: `None`

> The custom domain to use for generating URLs for files. For example, `www.mydomain.com` or `mycdn.azureedge.net`.

`AZURE_TOKEN_CREDENTIAL`

> A token credential used to authenticate HTTPS requests. The token value should be updated before its expiration.

`cache_control` or `AZURE_CACHE_CONTROL`

> Default: `None`

> A variable to set the Cache-Control HTTP response header. E.g.:

>     cache_control: "public,max-age=31536000,immutable"

`object_parameters` or `AZURE_OBJECT_PARAMETERS`

> Default: `{}`

> Use this to set content settings on all objects. To set these on a per-object basis, subclass the backend and override `AzureStorage.get_object_parameters`.

> This is a Python `dict` and the possible parameters are: `content_type`, `content_encoding`, `content_language`, `content_disposition`, `cache_control`, and `content_md5`.

`api_version` or `AZURE_API_VERSION`

> Default: `None`

> The api version to use.

## Additional Notes

### Filename Restrictions

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

- end with a dot (`.`) or slash (`/`)

- contain more than 256 slashes (`/`)

- be longer than 1024 characters

### Private vs Public URLs

The difference between public and private URLs is that private includes the SAS token. With private URLs you can override certain properties stored for the blob by specifying query parameters as part of the shared access signature. These properties include the cache-control, content-type, content-encoding, content-language, and content-disposition. See https://docs.microsoft.com/en-us/rest/api/storageservices/set-blob-properties#remarks

You can specify these parameters by:

    az_storage = AzureStorage()
    az_url = az_storage.url(blob_name, parameters={'content_type': 'text/html;'})