Github Actions cheatsheet

GitHub Actions is a CI/CD platform that enables automation of software workflows, allowing developers to build, test, and deploy code right from their GitHub repositories.

Github Action Workflows are defined in special YAML files, typically stored in a .github/workflows directory in the github repository.

name: hello-world
on: push
jobs:
  hello-world-job:
    runs-on: ubuntu-latest
    steps:
      - name: Hello World
        run: echo "Hello World!"

Viewing your workflow runs

• On GitHub.com, navigate to the main page of the repository.
• Under your repository name, click Actions.
• In the left sidebar, click the workflow you want to display, in this example "hello-world"

name: learn-github-actions
run-name: ${{ github.actor }} is learning GitHub Actions
on: [push]
jobs:
  check-bats-version:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v3
        with:
          node-version: '14'
      - run: npm install -g bats
      - run: bats -v

name: Event-trigger-on-push-example

on: [push] # event is defined here

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Run a script
      run: echo "This workflow runs on every push to the repository."

Event Triggers

Single Job:

name: Single Job
on: [push]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Run a build script
      run: script/build

Multiple Jobs:

name: CI Workflow

on: [push]

jobs:
  job-1:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Runs job 1 
      run: echo "Running Job 1"

  job-2:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Runs job 2 
      run: echo "Running Job 2"

  job-3:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Runs job 3 
      run: echo "Running Job 3"

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    # step 1 
    - name: Check out repository 
      uses: actions/checkout@v2
    
    # step 2 
    - name: Set up Node.js
      uses: actions/setup-node@v2
      with:
        node-version: '14'
    
    # step 3 
    - name: Install dependencies
      run: npm install

    # step 4
    - name: Run tests
      run: npm test

Github Hosted Runner:

name: Workflow
on: [push]
jobs:
  build:
    runs-on: ubuntu-latest # default runner 
    steps:
    - uses: actions/checkout@v2
    - name: Run a script
      run: echo "Hello, world!"

Self Hosted Runner

name: Workflow with Self-Hosted Runner
on: [push]
jobs:
  build:
    runs-on: self-hosted
    steps:
    - uses: actions/checkout@v2
    - name: Run a script
      run: echo "Hello from self-hosted runner!"

Custom variable defined using environments.

jobs:
  build:
    runs-on: ubuntu-latest
    env:
      CUSTOM_VARIABLE: "Hello, World!" # Custom variable defined using env:
    steps:
      - name: Check environment variable
        run: echo "Value of CUSTOM_VAR is $CUSTOM_VAR"

To add a new secret in your github repository nagivate to Repository > Settings > Security > Secrets and Variables > Actions > New Repository Secret

Example Secrets workflow:

name: Workflow with Secrets

on: [push]

jobs:
  example_job:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout repository
      uses: actions/checkout@v2
    - name: Use a secret
      run: echo "The secret is ${{ secrets.MY_SECRET }}"

To access your artifact navigate to Repository > Actions > Workflow Run > Artifacts

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Build project
      run: make build
    - name: Upload build artifact
      uses: actions/upload-artifact@v3 # upload Artifacts prebuilt action
      with:
        name: my-artifact
        path: path/to/artifact

Dependency caches stores downloaded packages or compiled binaries of your workflows.

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Cache dependencies
      uses: actions/cache@v2 # stores downloaded packages or compiled binaries
      with:
        path: |
          path/to/dependencies
          another/path
        key: ${{ runner.os }}-deps-${{ hashFiles('**/lockfile') }} # hash of the dependency lock file is generated in the OS
    - name: Install dependencies
      run: install-command

jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [12.x, 14.x, 16.x]
        # matrix strategy runs enables you to run jobs across multiple combinations of environments and OS's
        os: [ubuntu-latest, windows-latest, macOS-latest] 
    steps:
    - uses: actions/checkout@v2
    - name: Use Node.js ${{ matrix.node-version }}
      uses: actions/setup-node@v1
      with:
        node-version: ${{ matrix.node-version }}
    - run: npm install
    - run: npm test
      env:
        CI: true

Branch Conditions:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout code
      uses: actions/checkout@v2
    - name: Run build
      if: github.ref == 'refs/heads/main' # "Run build" step will only execute if the current branch is main.
      run: make build

Event Trigger Conditions:

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout code
      uses: actions/checkout@v2
    - name: Run tests
      if: github.event_name == 'pull_request' # "Run tests" step is executed only when the workflow is triggered by a pull request event
      run: npm test

Depending on your OS, if you are running ubuntu-latest, bash commands should work

steps:
  - name: Set environment variable
    run: echo "NAME=value" >> $GITHUB_ENV

The concurrency field creates a group based on the github.head_ref. If a new run starts within the same concurrency group, it cancels any in-progress runs.

jobs:
  my_job:
    runs-on: ubuntu-latest
    concurrency: 
      group: ${{ github.head_ref }}
      cancel-in-progress: true
    steps:
    - name: Run a script
      run: echo "Running script..."