I’m deploying a Django application on Google App Engine, and I’m using a private Google Cloud Storage (GCS) bucket (mystatic) to serve static files. I’ve configured django-storages and google-cloud-storage for Django to use the GCS bucket, with the appropriate settings:
- Created a custom service account for my App Engine instance.
- Granted the service account Storage Object Viewer permissions on the mystatic bucket to ensure it has access to the static files.
- Configured STATICFILES_STORAGE and DEFAULT_FILE_STORAGE in Django to use storages.backends.gcloud.GoogleCloudStorage and set GS_BUCKET_NAME to mystatic.
- Configured STATIC_URL = ‘https://storage.googleapis.com/mystatic/static’
Despite these configurations, I’m still receiving a 403 Access Denied error when the app attempts to access files in the GCS bucket.
Questions:
- Are there additional steps required to authenticate App Engine with a custom service account for GCS access?
- Does Google App Engine require explicitly setting GOOGLE_APPLICATION_CREDENTIALS for custom service accounts, or should it automatically use the assigned service account for bucket access? If it does then is it safe to use this in production?
- Is there anything specific to file or bucket permissions that might cause this persistent 403 error?
Any guidance or insights on resolving this access issue would be greatly appreciated!
Hi @flyingjet ,
Welcome to Google Cloud Community!
The error 403 indicates that the user was not authorized by Cloud Storage to make the request. A common source of this error is that the bucket permissions are not set properly to allow your app access.
To help you with this, you might need to try to grant the Storage Admin (roles/storage.admin) role to your custom service account either at the bucket-level or at the project-level (where the bucket resides).
Also, you may check this IAM for Cloud Storage documentation for your reference.
I hope the above information is helpful.
It sounds like you’ve taken many of the correct steps, but there may be a few additional configurations to check to resolve the 403 error:
Service Account Key Authentication: For Google App Engine, the default service account should automatically provide authentication to GCS without needing GOOGLE_APPLICATION_CREDENTIALS. Ensure that your App Engine app is indeed running under the custom service account you’ve set up, and that it has the necessary permissions. This setup should be production-safe, as Google manages secure authentication within the environment.
Permissions Check: Verify that the Storage Object Viewer role is applied directly to the custom service account for the specific mystatic bucket. Additionally, check the bucket’s IAM policies and ensure there’s no condition attached to the role that might be restricting access (e.g., location-specific constraints).
File and Bucket Settings: Sometimes, a 403 error arises if individual files or folders within the bucket have different permissions. Double-check that files you’re trying to access inherit the bucket-level permissions.
Cache and Access Control Settings: Ensure that the bucket is correctly set for private access if that’s your intention, and confirm that Django is not caching incorrect permissions.
Testing with Permissions: You could temporarily grant Storage Object Admin to the service account to rule out any permissions issues; then, if successful, revert back to Storage Object Viewer.
If the issue persists after these checks, enabling detailed logging on Google Cloud Storage can offer more insights into why access is being denied.