GitHub Actions is a CI/CD platform that allows you to automate your build, test, and deployment pipeline directly within GitHub repositories. Unlike traditional CI/CD tools like Jenkins or TeamCity that require separate infrastructure, GitHub Actions is cloud-native and integrated directly into GitHub.

Key differences:

• Native Integration: Seamlessly integrated with GitHub repositories, pull requests, and issues
• Event-driven: Triggers on various GitHub events (push, pull request, release, etc.)
• Marketplace: Extensive marketplace of pre-built actions
• YAML Configuration: Uses simple YAML files stored in .github/workflows/
• No Infrastructure Management: Hosted runners eliminate the need to manage servers

A GitHub Actions workflow is defined in a YAML file within the .github/workflows/ directory. The basic structure includes:

name: CI Pipeline
on: [push, pull_request]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '18'
      - name: Install dependencies
        run: npm install
      - name: Run tests
        run: npm test

Key components:

• name: Optional workflow name
• on: Events that trigger the workflow
• jobs: Collection of steps that execute on the same runner
• runs-on: Specifies the runner environment
• steps: Individual tasks within a job
• uses: References pre-built actions
• run: Executes shell commands

GitHub Actions supports various trigger events:

Repository Events:

• push: Code pushed to repository
• pull_request: PR opened, synchronized, or closed
• release: Release published or created
• create: Branch or tag created
• delete: Branch or tag deleted

Scheduled Events:

• schedule: Cron-based scheduling using cron syntax

Manual Events:

• workflow_dispatch: Manual trigger with optional inputs
• repository_dispatch: Triggered via API calls

External Events:

• webhook: Custom webhook events
• check_run: Check run completed
• deployment: Deployment event

Example:

on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]
  schedule:
    - cron: '0 2 * * *'  # Daily at 2 AM
  workflow_dispatch: