GitHub Actions: Fundamentals 🔥

Workflows, Jobs & Steps #

⚙️ Workflows #

• Attached to GitHub repository
• Contain one or more Jobs
• Triggered upon Events

🔧 Jobs #

• Define a Runner (execution environment / operating system to execute the steps)
• Contain one or more Steps
• Run in parallel (default) or sequential
• Can be conditional

👣 Steps #

• Execute a shell script, command or an Action
• Can use custom or third-party actions
• Steps are executed in order
• Can be conditional

📄 File: .github/workflows/01-first-action.yml

name: First Workflow
on: workflow_dispatch
jobs:
  first-job:
    runs-on: ubuntu-latest
    steps:
      - name: Print greeting
        run: echo "Hello World!"
      - name: Print goodbye
        run: echo "Done - bye!"

ℹ️ If you need to run multiple shell commands, you can easily do so by adding the pipe symbol (|) as a value after the run: key:

    steps:
      - name: Print greeting
        run: | 
	        echo "Hello World!"
	        echo "Hello Solar System!"

This will run both commands in one step.

Events (Workflow Triggers) #

Example:

📄 File: .github/workflows/04-01-exercise.yml

name: 04-01 - Exercise - Events
on:
  pull_request:
    types:
      - opened
    branches:
      - main # main
      - 'dev-*' # dev-new dev-this-is-new
      - 'feat/**' # feat/new feat/new/button
  workflow_dispatch:
  push:
    branches:
      - main # main
      - 'dev-*' # dev-new dev-this-is-new
      - 'feat/**' # feat/new feat/new/button
      # developer-1
    paths-ignore:
      - '.github/workflows/*' # If files in .github/workflows change, workflow will not run
jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Output event data
        run: echo "${{ toJSON(github.event) }}"
      - name: Get code
        uses: actions/checkout@v3
      - name: Install dependencies
        run: |
          cd 04-react-exercise
          npm ci
      - name: Test code
        run: |
          cd 04-react-exercise
          npm run test
      - name: Build code
        run: |
          cd 04-react-exercise
          npm run build
      - name: Deploy project
        run: echo "Deploying..."

More info:

• Events that trigger workflows
• Workflow syntax for GitHub Actions

Job Runners #

More: GitHub Actions Runners

Contexts reference #

Available contexts #

The following example demonstrates how these different types of variables can be used together in a job:

name: CI
on: push
jobs:
  prod-check:
    if: ${{ github.ref == 'refs/heads/main' }}
    runs-on: ubuntu-latest
    steps:
      - run: echo "Deploying to production server on branch $GITHUB_REF"

Another example demonstrates how to output a GitHub context in JSON format:

📄 File: .github/workflows/03-output.yml

name: 03 - Output information
on: workflow_dispatch
jobs:
  info:
    runs-on: ubuntu-latest
    steps:
      - name: Output GitHub context
        run: echo "${{ toJSON(github) }}"

More: GitHub Actions Contexts

Skipping workflow runs #

Workflows that would otherwise be triggered using on: push or on: pull_request won’t be triggered if you add any of the following strings to the commit message in a push, or the HEAD commit of a pull request:

• [skip ci]
• [ci skip]
• [no ci]
• [skip actions]
• [actions skip]

Alternatively, you can add a skip-checks trailer to your commit message. The trailers section should be included at the end of your commit message and be preceded by two empty lines. If you already have other trailers in your commit message, skip-checks should be last. You can use either of the following:

• skip-checks:true
• skip-checks: true

More: Skipping workflow runs

» Sources « #

• GitHub Event Triggers - to indicate when to run (on:).
• Workflow syntax for GitHub Actions - Workflow syntax.
• GitHub Actions Runners - execution environment / operating system to execute the steps.
• GitHub Actions billing - GitHub Actions billing information.
• Managing GitHub Actions settings for a repository
• GitHub Actions Contexts - get metadata from GitHub about the job and environment where actions run. Useful for outputs and investigating issues.
• Skipping workflow runs - skipping workflow runs with appropriate commit message. Useful for minor code changes (updating comments, etc.)

» Disclaimer « #