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omsf-eco-infra / gha-runner

A simple GitHub Action for creating cloud-based self-hosted runners.
MIT License
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gha-runner

A simple GitHub Action for creating self-hosted runners. Currently, this only supports AWS and x86_64 Linux AMIs. This runner is heavily inspired by ec2-github-runner but rewritten to support additional cloud providers and to better meet some needs of the OMSF community.

A note on security before using this action

The following is a note from GitHub on using self-hosted runners on public repos.

We recommend that you do not use self-hosted runners with public repositories.

Forks of your public repository can potentially run dangerous code on your self-hosted runner machine by creating a pull request that executes the code in a workflow.

For more information see the self-hosted runner security docs. As well as some good community recommendations and pitfalls. We do not recommend running these pipelines on a PR.

Cloud Setup Docs

Example Setups

Inputs

Shared Inputs

Input Description Required Default
action Whether to start or stop. Options: "start", "stop" true
provider The cloud provider to use to provision a runner. Will not start if not set. true
repo The repo to run against. Will use the current repo if not specified. false The repo the runner is running in

AWS start Inputs

Input Description Required for start Default
aws_home_dir The AWS AMI home directory to use for your runner. Will not start if not specified. true
aws_iam_role The optional AWS IAM role to assume for provisioning your runner. false
aws_image_id The machine AMI to use for your runner. This AMI can be a default but should have docker installed in the AMI. true
aws_instance_type The type of instance to use for your runner. For example: t2.micro, t4g.nano, etc. Will not start if not specified. true
aws_region_name The AWS region name to use for your runner. Will not start if not specified. true
aws_security_group_id The AWS security group ID to use for your runner. Will use the account default security group if not specified. false The default AWS security group
aws_subnet_id The AWS subnet ID to use for your runner. Will use the account default subnet if not specified. false The default AWS subnet ID
aws_tags The AWS tags to use for your runner, formatted as a JSON list. See README for more details. false
extra_gh_labels Any extra GitHub labels to tag your runners with. Passed as a comma-separated list with no spaces. false
instance_count The number of instances to create, defaults to 1 false 1
gh_timeout The timeout in seconds to wait for the runner to come online as seen by the GitHub API. Defaults to 1200 seconds. false 1200

AWS stop Inputs

Input Description Required for stop Default Note
instance_mapping A JSON object mapping instance ids to unique GitHub runner labels This should be the same as the AWS start output, mapping. Required to stop created instances. true This should be the mapping output as generated by the start run.

Outputs

Name Description
mapping A JSON object mapping instance IDs to unique GitHub runner labels. This is used in conjunction with the instance_mapping input when stopping.
instances A JSON list of the GitHub runner labels to be used in the 'runs-on' field

Testing the action in development

Testing the action was primarily done using nektos/act to test locally. To do a test run with some basic defaults:

name: Testing
on: [push]

jobs:
  hello_world_job:
    runs-on: ubuntu-latest
    name: Test the gha_runner
    steps:
      # To use this repository's private action,
      # you must check out the repository
      - name: Checkout
        uses: actions/checkout@v4
      - name: Local runner run
        id: aws_start
        uses: ./ # Uses an action in the root directory
        with:
          repo: "testing/testing"
          provider: "aws"
          action: "start"
          aws_image_id: <use an image here that has docker installed>
          aws_instance_type: t2.micro
          instance_count: 2
          aws_region_name: us-east-1
          aws_home_dir: /home/ec2-user
          aws_labels: testing
        env:
          GH_PAT: ${{ secrets.GH_PAT }}
          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
      - name: Stop instances
        uses: ./
        with:
          repo: "testing/testing"
          provider: "aws"
          action: "stop"
          instance_mapping: ${{ steps.aws_start.outputs.mapping }}
          aws_region_name: us-east-1
        env:
          GH_PAT: ${{ secrets.GH_PAT }}
          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}

NOTE: For guidelines on setting secrets view the act docs found here This file was placed in a test-worklows directory.

Then it was run using the following:

act -W test-workflows/ --verbose

For testing on M-series Macs, use the following command instead:

act --container-architecture linux/arm64 -W test-workflows/ --verbose

Acknowledgements

This action was heavily inspired by the ec2-github-runner. This action takes much of its structure and inspiration around architecture from the ec2-github-runner itself. Thank you to the authors of that action for providing a solid foundation to build upon.