GitHub Runner Infrastructure

If you make any changes to the infrastructure code in this directory, you will have to redeploy it. Do the following:

1. Make sure you're logged into AWS. You can check using awscli2:

   ❯ nix run nixpkgs#awscli2 -- sts get-caller-identity
   {
     # CENSORED
   }

   If this fails, log in with AWS SSO credentials, following their guide. You will likely hit a bug in the AWS provider. Apply the workaround mentioned in a comment and log in again using aws sso login to resolve this.

2. Make sure you're logged into GitHub. You can check using gh:

   ❯ nix run github:nixos/nixpkgs#gh -- auth status
   github.com
     # CENSORED
     ✓ Token scopes: gist, read:org, repo

   If this fails, log in using nix run nixpkgs#gh -- auth login and follow the instructions.

3. Update the infrastructure using

   nix develop ..#infra -c update-infra

Architecture

The code in this subdirectory provisions AWS infrastucture for starting an ARM64 GitHub Actions runner on demand. The workflow for producing ARM64 release artifacts is as follows:

• the release workflow is triggered automatically when a release is created or manually for testing
• the workflow requests a runner registration token $TOKEN from the GitHub API. For this, it needs a personal access token with repo scope for the Nickel repository.
• the workflow invokes the $EC2_START AWS Lambda and provides $TOKEN as input
• the AWS Lambda stores $TOKEN as a parameter in the AWS SSM and requests an appropriate EC2 spot instance
• the spot instance boots up, retrieves $TOKEN from AWS SSM and starts a GitHub Actions runner
• GitHub Actions schedules the ARM64 jobs on the spot instance
• when the jobs building the release artifact have finished, the workflow invokes the $EC2_STOP AWS Lambda which terminates the EC2 instance