fix(expiration): Add expiration back

Signed-off-by: dark0dave <dark0dave@mykolab.com>

docs/backends/gcloud.rst

@@ -219,3 +219,12 @@ Settings
   It supports `timedelta`, `datetime`, or `integer` seconds since epoch time.
 
   Note: The maximum value for this option is 7 days (604800 seconds) in version `v4` (See this `Github issue  <https://github.com/googleapis/python-storage/issues/456#issuecomment-856884993>`_)
+
+``sa_email`` or ``GS_SA_SIGNING_EMAIL``
+
+  default: ``''``
+
+  This is the signing email if it is not fetched from the credentials. Or if you wish to sign the signed urls with a different service_account.
+
+  As above please note that, Default Google Compute Engine (GCE) Service accounts are
+  `unable to sign urls <https://googlecloudplatform.github.io/google-cloud-python/latest/storage/blobs.html#google.cloud.storage.blob.Blob.generate_signed_url>`_.

storages/backends/gcloud.py

@@ -155,7 +155,6 @@ def client(self):
         credentials.refresh(requests.Request())
         if not hasattr(credentials, "service_account_email"):
             credentials.service_account_email = self.sa_email
-        _LOGGER.debug(f"Signing email: {credentials.service_account_email}")
         self.credentials = credentials
         if self._client is None:
             self._client = Client(project=project_id, credentials=self.credentials)
@@ -330,9 +329,13 @@ def url(self, name, parameters=None):
                 quoted_name=_quote(name, safe=b"/~"),
             )
         elif not self.custom_endpoint:
-            return blob.generate_signed_url(**self.signed_url_extra())
+            return blob.generate_signed_url(
+                expiration=self.expiration,
+                **self.signed_url_extra()
+            )
         else:
             return blob.generate_signed_url(
+                expiration=self.expiration,
                 api_access_endpoint=self.custom_endpoint,
                 **self.signed_url_extra()
             )