Per-PR preview environments on Google Cloud: deploy on a label, tear down when the PR closes. A Google Cloud version of the preview environment setup in this blog post.

flowchart LR
    subgraph "GitHub"
        repoA["Repo A PR #12"]
        repoB["Repo B PR #34"]
    end

    repoA -->|preview label| build[Cloud Build]
    repoB -->|preview label| build
    build -->|push| ar[Artifact Registry]
    build -->|push| ar

    subgraph iapA["IAP"]
        subgraph "Cloud Run: PR #12"
            f1[frontend]
            b1[backend]
            d1[db]
        end
    end
    subgraph iapB["IAP"]
        subgraph "Cloud Run: PR #34"
            f2[frontend]
            b2[backend]
            d2[db]
        end
    end

    ar -->|deploy| f1
    ar -->|deploy| f2

.
├── backend/, frontend/, db/    sample app deployed by this repo's own preview environment
├── terraform/
│   ├── base/                  one-time foundation (applied once, locally, by the project owner)
│   ├── modules/preview/       reusable Cloud Run preview module — other repos call this
│   └── env/preview/           this repo's own calling example
└── .github/workflows/
    ├── reusable-{deploy,destroy,gc}-prenv.yml   reusable workflows (workflow_call)
    └── deploy-prenv.yml, teardown-prenv.yml, gc-prenv.yml      thin triggers that call the above

Prerequisites, from the project owner:

• the six values GCP_PROJECT_ID, WIF_PROVIDER, DEPLOY_SA, BUILD_SA, AR_REPO, GCS_BUCKET
• your repo added to base's github_repositories

Run the setup-prenv skill (.claude/skills/setup-prenv) in your repo. It automates:

• creating the preview GitHub environment and setting the six values above
• creating the preview label
• writing deploy-prenv.yml / teardown-prenv.yml / gc-prenv.yml trigger workflows that call this repo's reusable workflows
• writing a terraform/env/preview stub that calls terraform/modules/preview

See docs/DESIGN.md for how the module and reusable workflows are referenced.

• Add the preview label to a PR → a preview URL is commented on the PR.
• Close the PR (or run the teardown workflow manually) → the environment is destroyed.
• Idle 3+ days → swept by the daily GC.

• docs/DESIGN.md — design decisions and rationale.
• CONTRIBUTING.md — dev environment setup and how to submit changes.