Allow custom endpoints with Google Cloud Storage.

Add new `GS_CUSTOM_ENDPOINT` setting to allow usage of custom
domains/URLs with Google Cloud Storage, similar to
`AWS_S3_CUSTOM_DOMAIN`.

docs/backends/gcloud.rst

@@ -142,6 +142,11 @@ rolled over into a temporary file on disk. Default is 0: Do not roll over.
 
 Sets Cache-Control HTTP header for the file, more about HTTP caching can be found `here <https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching#cache-control>`_
 
+``GS_CUSTOM_ENDPOINT`` (optional: default is ``None``)
+
+Sets a `custom endpoint <https://cloud.google.com/storage/docs/request-endpoints>`_,
+that will be used instead of ``https://storage.googleapis.com`` when generating URLs for files.
+
 ``GS_LOCATION`` (optional: default is ``''``)
 
 Subdirectory in which the files will be stored.

storages/backends/gcloud.py

@@ -8,13 +8,15 @@
 from django.utils import timezone
 from django.utils.deconstruct import deconstructible
 from django.utils.encoding import force_bytes, smart_str
+from django.utils.six.moves.urllib.parse import quote
 
 from storages.utils import (
     check_location, clean_name, get_available_overwrite_name, safe_join,
     setting,
 )
 
 try:
+    from google.cloud.storage._signing import generate_signed_url
     from google.cloud.storage.client import Client
     from google.cloud.storage.blob import Blob
     from google.cloud.exceptions import NotFound
@@ -86,6 +88,7 @@ class GoogleCloudStorage(Storage):
     project_id = setting('GS_PROJECT_ID')
     credentials = setting('GS_CREDENTIALS')
     bucket_name = setting('GS_BUCKET_NAME')
+    custom_endpoint = setting('GS_CUSTOM_ENDPOINT', None)
     location = setting('GS_LOCATION', '')
     auto_create_bucket = setting('GS_AUTO_CREATE_BUCKET', False)
     auto_create_acl = setting('GS_AUTO_CREATE_ACL', 'projectPrivate')
@@ -262,9 +265,22 @@ def url(self, name):
         name = self._normalize_name(clean_name(name))
         blob = self.bucket.blob(self._encode_name(name))
 
-        if self.default_acl == 'publicRead':
+        if not self.custom_endpoint and self.default_acl == 'publicRead':
             return blob.public_url
-        return blob.generate_signed_url(self.expiration)
+        elif self.default_acl == 'publicRead':
+            return '{storage_base_url}/{quoted_name}'.format(
+                storage_base_url=self.custom_endpoint,
+                quoted_name=quote(name.encode('utf-8')),
+            )
+        elif not self.custom_endpoint:
+            return blob.generate_signed_url(self.expiration)
+        else:
+            return generate_signed_url(
+                self.credentials,
+                resource=quote(name.encode('utf-8')),
+                api_access_endpoint=self.custom_endpoint,
+                expiration=self.expiration,
+            )
 
     def get_available_name(self, name, max_length=None):
         name = clean_name(name)

tests/test_gcloud.py

@@ -358,6 +358,18 @@ def test_url_not_public_file_with_custom_expires(self):
         self.assertEqual(url, 'http://signed_url')
         blob.generate_signed_url.assert_called_with(timedelta(seconds=3600))
 
+    def test_custom_endpoint(self):
+        self.storage.custom_endpoint = "https://example.com"
+
+        self.storage.default_acl = 'publicRead'
+        url = "{}/{}".format(self.storage.custom_endpoint, self.filename)
+        self.assertEqual(self.storage.url(self.filename), url)
+
+        signed_url = 'https://signed_url'
+        self.storage.default_acl = 'projectPrivate'
+        gcloud.generate_signed_url = mock.MagicMock(return_value=signed_url)
+        self.assertEqual(self.storage.url(self.filename), signed_url)
+
     def test_get_available_name(self):
         self.storage.file_overwrite = True
         self.assertEqual(self.storage.get_available_name(