Start your EC2 self-hosted runner right before you need it. Run the job on it. Finally, stop it when you finish. And all this automatically as a part of your GitHub Actions workflow.

Table of Contents

• Use cases
  • Access private resources in your VPC
  • Customize hardware configuration
  • Save costs
• Usage
  • How to start
  • Inputs
  • Environment variables
  • Outputs
  • Example
• Self-hosted runner security with public repositories
• License Summary

Use cases

Access private resources in your VPC

The action can start the EC2 runner in any subnet of your VPC that you need - public or private. In this way, you can easily access any private resources in your VPC from your GitHub Actions workflow.

For example, you can access your database in the private subnet to run the database migration.

Customize hardware configuration

Some of your CI workloads may require more powerful hardware that GitHub-hosted runners provide. In the action, you can configure any EC2 instance type for your runner that AWS provides.

For example, you may run c5.4xlarge EC2 runner for some of your compute-intensive workloads. Or r5.xlarge EC2 runner for workloads that process large data sets in memory.

Save costs

If your CI workloads don't need the power of the GitHub-hosted runners and the execution takes more than a couple of minutes, you can consider running it on a cheaper and less powerful instance from AWS.

According to GitHub's documentation, you don't need to pay for the jobs handled by the self-hosted runners:

Self-hosted runners are free to use with GitHub Actions, but you are responsible for the cost of maintaining your runner machines.

So you will be charged by GitHub only for the time the self-hosted runner start and stop. EC2 self-hosted runner will handle everything else so that you will pay for it to AWS, which can be less expensive than the price for the GitHub-hosted runner.

Usage

How to start

Use the following steps to prepare your workflow for running on your EC2 self-hosted runner:

1. Prepare AWS access keys

1. Create new AWS access keys with the following least-privilege permissions. The action will use the keys for EC2 instance management in the AWS account.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "ec2:RunInstances",
        "ec2:TerminateInstances",
        "ec2:DescribeInstances",
        "ec2:DescribeInstanceStatus"
      ],
      "Resource": "*"
    }
  ]
}

2. Add the keys to GitHub secrets.
3. Use the aws-actions/configure-aws-credentials action to put the keys into environment variables.

2. Prepare GitHub personal access token

1. Create a new GitHub personal access token with the repo scope. The action will use the token for self-hosted runners management in the GitHub account on the repository level.
2. Add the token to GitHub secrets.

3. Prepare EC2 image

1. Create a new EC2 image (AMI) from the Linux distribution you need. You don't need to install anything special beforehand into the AMI. The action will install all the necessary tools during the EC2 instance creation.

4. Prepare VPC with subnet and security group

1. Create a new VPC and a new subnet in it. Or use the existing VPC and subnet.
2. Create a new security group for the runners in the VPC. The runner doesn't require any inbound traffic. However, outbound traffic for port 443 should be allowed so the runner can pull GitHub Actions' tasks.

Note: Make sure your EC2 instance has access to the internet in order to connect to GitHub Actions and pull the tasks.

5. Configure the GitHub workflow

1. Create a new GitHub Actions workflow or edit the existing one.
2. Use the documentation and example below to configure your workflow.
3. Please don't forget to set up a job for removing the EC2 instance at the end of the workflow execution. Otherwise, the EC2 instance won't be removed and continue to run even after the workflow execution is finished.

Now you're ready to go!

Inputs

Environment variables

In addition to the inputs described above, the action also requires the following environment variables to access your AWS account:

• AWS_DEFAULT_REGION
• AWS_REGION
• AWS_ACCESS_KEY_ID
• AWS_SECRET_ACCESS_KEY

We recommend using aws-actions/configure-aws-credentials action right before running the step for creating a self-hosted runner. This action perfectly does the job of setting the required environment variables.

Outputs

Example

The workflow showed in the picture above and declared in do-the-job.yml looks like this:

name: do-the-job
on: pull_request
jobs:
  start-runner:
    name: Start self-hosted EC2 runner
    runs-on: ubuntu-latest
    outputs:
      label: ${{ steps.start-ec2-runner.outputs.label }}
      ec2-instance-id: ${{ steps.start-ec2-runner.outputs.ec2-instance-id }}
    steps:
      - name: Configure AWS credentials
        uses: aws-actions/configure-aws-credentials@v1
        with:
          aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
          aws-region: ${{ secrets.AWS_REGION }}
      - name: Start EC2 runner
        id: start-ec2-runner
        uses: machulav/ec2-github-runner@v1.0.0
        with:
          mode: start
          github-token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }}
          ec2-image-id: ami-123
          ec2-instance-type: t3.nano
          subnet-id: subnet-123
          security-group-id: sg-123
  do-the-job:
    name: Do the job on the runner
    runs-on: ${{ needs.start-runner.outputs.label }} # run the job on the newly created runner
    needs: start-runner # required to start the main job when the runner is ready
    steps:
      - name: Hello World
        run: echo 'Hello World!'
  stop-runner:
    name: Stop self-hosted EC2 runner
    runs-on: ubuntu-latest
    needs:
      - start-runner # required to get output from the start-runner job
      - do-the-job # required to wait when the main job is done
    if: ${{ always() }} # required to stop the runner even if the error happened in the previous jobs
    steps:
      - name: Configure AWS credentials
        uses: aws-actions/configure-aws-credentials@v1
        with:
          aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
          aws-region: ${{ secrets.AWS_REGION }}
      - name: Stop EC2 runner
        uses: machulav/ec2-github-runner@v1.0.0
        with:
          mode: stop
          github-token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }}
          label: ${{ needs.start-runner.outputs.label }}
          ec2-instance-id: ${{ needs.start-runner.outputs.ec2-instance-id }}

Self-hosted runner security with public repositories

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.

Please find more details about this security note on GitHub documentation.

License Summary

This code is made available under the MIT license.