Authenticate to Google Cloud

The auth action, from the google-github-actions organization, authenticates GitHub Actions workflows to Google Cloud. It supports authentication through Workload Identity Federation or a Google Cloud service account key JSON, so later workflow steps can call Google Cloud services with the right identity.

Workload Identity Federation is recommended over service account keys because it avoids exporting a long-lived credential and creates a trust relationship between a particular workflow run and permissions on Google Cloud. There are three setup modes: direct Workload Identity Federation, which is preferred, Workload Identity Federation through a service account, and a service account key JSON. A checkout step must run before the action, credentials files should be kept out of release artifacts through ignore files, and the action runs on Node 24, so the runner version must support it. The gsutil command will not use the exported credentials; gcloud storage should be used instead.

The README states it is not an officially supported Google product and is not covered by a Google Cloud support contract. The action is written in TypeScript and licensed under Apache-2.0.