Amazon EC2 Github Actions Runners

[swahtz]

Introduction

To support unit and integration tests that run on supported GPU hardware, we utilize Amazon EC2 instances to run the jobs of Github Actions that require this hardware.

In order to facilitate starting an EC2 instance, registering the instance as a self-hosted runner of this repository and shut it down (and remove it as a runner), we use this Github action: https://github.com/machulav/ec2-github-runner

Generally, the structure of running a task that requires a specific instance type looks like:

1. Start runner (outputs registered runner label)
   1. Configure AWS credentials
   2. Start runner instance of specified type
2. Run task
   1. Run the required task (runs-on: Start runner's output label)
3. Stop runner
   1. Configure AWS credentials
   2. Stop runner instance

Start runner and stop runner run on default Github actions Linux instances.

Registering EC2 Instances as Github Actions Self-Hosted Runners

The ec2-github-runner action takes care of starting the EC2 instance and getting it registered to the repository as a self-hosted Github Actions runner. To do this it requires the permissions provided by a token with repo access (see the action's documentation for further details). The token is provided as a Actions repo secret and the actions run as pull_request_target so that job definitions always run from the target branch of a PR for security.

Generating required token

If the token that provides these permissions expires or needs to be regenerated, a maintainer can follow these steps to make and register a new one:

1. Go to your GH account settings Developer->Personal Access Tokens->Tokens(classic)
2. Make a new token with repo permissions, copy the token
3. Go to the repo's Settings->Secrets and Variables->Actions
4. Either edit the existing token or add a new one if you want to change the name, paste in the value