Evaluate migrating CI from self-hosted runners to GitHub-hosted (Large) runners

[jolestar]

Background

We currently use self-hosted runners for multiple workflows, including check_build_test.yml, docker_build.yml, and deploy_{mainnet,testnet}.yml. The self-hosted CI pool is costly; recent billing analysis suggests meaningful savings if we migrate heavy builds to GitHub-hosted Large runners.

Goals

• Evaluate replacing the self-hosted runner for CI with GitHub-hosted Large runners (Linux).
• Confirm only check_build_test.yml requires Large runner capacity; others can use standard hosted runners.
• Assess impact and plan for deploy_* workflows (they currently SSH into GCP VMs and may need adjustments if moved off self-hosted).

Findings so far

• check_build_test.yml is the heavy workflow (Rust build/tests + Move + web/SDK + Docker pulls) and is the primary candidate for GitHub-hosted Large runner.
• docker_build.yml builds and pushes to GHCR; likely can run on standard hosted runners (no private network dependency), but includes a deploy-dev step that uses SSH to a GCP VM.
• deploy_mainnet.yml and deploy_testnet.yml are SSH-based deployments; migration to hosted runners likely needs IP allowlist changes or alternative deployment path.

Suggested next steps

1. Decide the target GitHub-hosted Large runner size (likely 16-core Linux to match n2d-standard-16).
2. Modify check_build_test.yml to use the Large runner label/group.
3. Migrate docker_build.yml build job to standard hosted runner; keep or refactor deploy-dev step.
4. Decide how to handle deploy_* workflows if self-hosted runners are removed.

References

• Actions runner pricing: https://docs.github.com/billing/reference/actions-runner-pricing
• Running jobs on larger runners: https://docs.github.com/en/actions/how-tos/using-github-hosted-runners/using-larger-runners/running-jobs-on-larger-runners?platform=linux