[docs][container] Document using GCP workload identity

[ianlewis]

Create a section in the README that outlines how to use GCP workload identity and gives pointers on how you need to set it up.

[chasen-bettinger]

Hey @ianlewis , I'd like to pick this ticket up if you think that's a good idea. What context are we trying to use GCP workload identity in and what are we trying to accomplish by using it?

[ianlewis]

@chasen-bettinger Go for it!

What context are we trying to use GCP workload identity in and what are we trying to accomplish by using it?

It's for authentication with GCP when pushing to Artifact Registry from the container generator.

I would add a new section to the README. There you can show an example of using it.

Some links that may be helpful:

• Setting up Workload Identity Federation: https://github.com/google-github-actions/auth#setting-up-workload-identity-federation
• Configuring OpenID Connect in Google Cloud Platform: https://docs.github.com/en/actions/deployment/security-hardening-your-deployments/configuring-openid-connect-in-google-cloud-platform
• Artifact Registry: Create a Docker repository: https://cloud.google.com/artifact-registry/docs/docker/store-docker-container-images#create