Add support for Azure CDN

It adds support for Azure CDN endpoints connected to Azure Storage accounts.

docs/backends/azure.rst

@@ -125,3 +125,13 @@ The following settings are available:
 ``AZURE_LOCATION``
 
     Default location for the uploaded files. This is a path that gets prepended to every file name.
+
+``AZURE_CDN_HOSTNAME``
+
+    Hostname (without protocol prefix) for Azure CDN endpoint connected to ``AZURE_ACCOUNT_NAME``,
+    e.g.::
+    
+        AZURE_CDN_HOSTNAME = 'foobar.azureedge.net'
+
+    If ``AZURE_CDN_HOSTNAME`` is set, it will be used instead of Azure Blob Storage
+    hostname in static file URLs generated with ``static`` template tag.

storages/backends/azure_storage.py

@@ -147,6 +147,7 @@ class AzureStorage(Storage):
     location = setting('AZURE_LOCATION', '')
     default_content_type = 'application/octet-stream'
     is_emulated = setting('AZURE_EMULATED_MODE', False)
+    cdn_hostname = setting('AZURE_CDN_HOSTNAME')
 
     def __init__(self):
         self._service = None
@@ -161,6 +162,8 @@ def service(self):
                 self.account_key,
                 is_emulated=self.is_emulated)
             self._service = account.create_block_blob_service()
+            if self.cdn_hostname is not None:
+                self._service.primary_endpoint = self.cdn_hostname
         return self._service
 
     @property

tests/test_azure.py

@@ -265,3 +265,9 @@ def test_last_modified_of_file(self):
         self.storage._service.get_blob_properties.return_value = Blob(props=props)
         time = self.storage.modified_time("name")
         self.assertEqual(accepted_time, time)
+
+    @mock.patch('storages.backends.azure_storage.CloudStorageAccount')
+    def test_azure_cdn(self, _):
+        storage = azure_storage.AzureStorage()
+        storage.cdn_hostname = 'foobar.azureedge.net'
+        self.assertEqual(storage.service.primary_endpoint, 'foobar.azureedge.net')