fix(cred): Use in built library instead of forced cred

docs/backends/gcloud.rst

@@ -61,6 +61,7 @@ For development use cases, or other instances outside Google infrastructure:
 
 Alternatively, you can use the setting ``credentials`` or ``GS_CREDENTIALS`` as described below.
 
+It is also now possible to use workload identity by providing the service account via ``GS_SA_SIGNING_EMAIL``.
 
 Settings
 ~~~~~~~~
@@ -219,3 +220,12 @@ 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>`_.

pyproject.toml

@@ -54,7 +54,7 @@ dropbox = [
   "dropbox>=7.2.1; python_version<'3.12'",
 ]
 google = [
-  "google-cloud-storage>=1.27",
+  "google-cloud-storage>=2.14",
 ]
 libcloud = [
   "apache-libcloud",

storages/backends/gcloud.py

@@ -20,6 +20,8 @@
 from storages.utils import to_bytes
 
 try:
+    from google import auth
+    from google.auth.transport import requests
     from google.cloud.exceptions import NotFound
     from google.cloud.storage import Blob
     from google.cloud.storage import Client
@@ -142,12 +144,18 @@ def get_default_settings(self):
             # roll over.
             "max_memory_size": setting("GS_MAX_MEMORY_SIZE", 0),
             "blob_chunk_size": setting("GS_BLOB_CHUNK_SIZE"),
+            "sa_email": setting("GS_SA_SIGNING_EMAIL")
         }
 
     @property
     def client(self):
         if self._client is None:
-            self._client = Client(project=self.project_id, credentials=self.credentials)
+            project_id, credentials = self.project_id, self.credentials
+            if project_id is None and credentials is None:
+                credentials, project_id = auth.default(scopes=['https://www.googleapis.com/auth/cloud-platform'])
+                if not hasattr(credentials, "service_account_email"):
+                    credentials.service_account_email = self.sa_email
+            self._client = Client(project=project_id, credentials=credentials)
         return self._client
 
     @property
@@ -319,17 +327,14 @@ def url(self, name, parameters=None):
                 quoted_name=_quote(name, safe=b"/~"),
             )
         else:
-            default_params = {
-                "bucket_bound_hostname": self.custom_endpoint,
+            params = {
+                "service_account_email": self.credentials.service_account_email,
+                "access_token": self.credentials.token,
+                "credentials": self.credentials,
                 "expiration": self.expiration,
-                "version": "v4",
             }
-            params = parameters or {}
-
-            for key, value in default_params.items():
-                if value and key not in params:
-                    params[key] = value
-
+            if self.custom_endpoint:
+                params["api_access_endpoint"] = self.custom_endpoint
             return blob.generate_signed_url(**params)
 
     def get_available_name(self, name, max_length=None):