writing-github-actions

Writing GitHub Actions

Create GitHub Actions workflows for CI/CD pipelines, automated testing, deployments, and repository automation using YAML-based configuration with native GitHub integration.

Purpose

GitHub Actions is the native CI/CD platform for GitHub repositories. This skill covers workflow syntax, triggers, job orchestration, reusable patterns, optimization techniques, and security practices specific to GitHub Actions.

Core Focus:

• Workflow YAML syntax and structure
• Reusable workflows and composite actions
• Matrix builds and parallel execution
• Caching and optimization strategies
• Secrets management and OIDC authentication
• Concurrency control and artifact management

Not Covered:

• CI/CD pipeline design strategy → See building-ci-pipelines
• GitOps deployment patterns → See gitops-workflows
• Infrastructure as code → See infrastructure-as-code
• Testing frameworks → See testing-strategies

When to Use This Skill

Trigger this skill when:

• Creating CI/CD workflows for GitHub repositories
• Automating tests, builds, and deployments via GitHub Actions
• Setting up reusable workflows across multiple repositories
• Optimizing workflow performance with caching and parallelization
• Implementing security best practices for GitHub Actions
• Troubleshooting GitHub Actions YAML syntax or behavior

Workflow Fundamentals

Basic Workflow Structure

name: CI
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npm test

Key Components:

• name: Workflow display name
• on: Trigger events (push, pull_request, schedule, workflow_dispatch)
• jobs: Job definitions (run in parallel by default)
• runs-on: Runner type (ubuntu-latest, windows-latest, macos-latest)
• steps: Sequential operations (uses actions or run commands)