Implicit credentials for GCP resources

[laurb9]

Allow implicit or default credentials for GCP resources (Vertex AI, GCS etc). As far as the application is concerned, this credential type is one that has no service key. It should just work, the same way as when you run gcloud in terminal.

It simplifies configuration for these cases:

• Deployment on local computer if I am already logged in to GCP
• Where credentials are supplied via the GOOGLE_APPLICATION_CREDENTIALS environment variable that gcloud libraries look for
• Google Kubernetes deployments that use Workload Id as the recommended way to set up access to GCP resources in GKE. It enables the gcloud libs to authenticate transparently against the cluster's metadata server, the roles are bound directly to the serviceAccount the pods run under.

This could be passed down to LiteLLM config as vertex_credentials: "os.environ/GOOGLE_APPLICATION_CREDENTIALS"

[github-actions[bot]]

This issue is stale because it has been open 75 days with no activity. Remove stale label or comment or this will be closed in 15 days.