What is GitHub Actions?

Short answer

GitHub Actions is an automation platform integrated into GitHub. It allows you to define workflows in YAML that run on GitHub-hosted or self-hosted runners in response to repository events.

How it works

Workflows are triggered by events like pushes, pull requests, or schedules. Each workflow contains jobs, which contain steps. Steps can run shell commands or use reusable actions from the GitHub Marketplace.

Example

name: CI
on: [push]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '18'
      - run: npm ci
      - run: npm test

Why it matters

GitHub Actions eliminates the need for a separate CI server. Its tight integration with GitHub, reusable actions, and matrix builds make it a powerful choice for many teams.

Tips

• Use workflow_dispatch for manual triggers.
• Cache dependencies with actions/cache.
• Pin actions to specific commits for security.

Common issues

• Public repository actions are free but private repos have minute limits.
• Self-hosted runners require maintenance and security hardening.
• YAML syntax errors are a common source of workflow failures.