--- name: github-ci description: Write and maintain GitHub Actions CI workflows, including workflow YAML structure, triggers, runners, matrix builds, caching, testing patterns, and secrets management. Use when working with .github/workflows, GitHub Actions, CI pipelines, workflow dispatch, or action configuration. license: MIT metadata: author: greedychipmunk version: "1.0" ---

# GitHub CI

Write and maintain GitHub Actions CI workflows with confidence. This skill covers workflow design, runner configuration, testing patterns, and security best practices for continuous integration pipelines on GitHub.

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## Intent Router

Load reference files for depth on specific topics:

| Topic | File | Load when... | | --- | --- | --- | | Workflow Basics | `resources/workflow-basics.md` | Learning workflow YAML structure, triggers, jobs, and built-in actions | | Runners & Caching | `resources/runners-and-caching.md` | Configuring runners, setting up caching, or optimizing build performance | | Testing Patterns | `resources/testing-patterns.md` | Implementing test runs, reporting results, or integrating coverage tools | | Security & Secrets | `resources/security-and-secrets.md` | Managing secrets, permissions, and third-party action safety |

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## Quick Start

### Basic GitHub Actions Workflow

1. **Create workflow file** — Save as `.github/workflows/ci.yml` in repository root 2. **Define triggers** — Use `on:` to specify when workflow runs (push, pull_request, schedule) 3. **Configure job** — Define jobs with name, runner type, and steps 4. **Add checkout** — Use `actions/checkout@v4` to access repository code 5. **Run commands** — Add steps with `run:` or use community actions

### Minimal Workflow

```yaml name: CI

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

jobs: test: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - run: echo "Running CI pipeline" ```

### Workflow Anatomy

```yaml workflow ├── name: Display name ├── on: Trigger events (push, pull_request, schedule, workflow_dispatch) ├── env: Workflow-level environment variables └── jobs: └── <job-name>: ├── runs-on: Runner type (ubuntu-latest, windows-latest, macos-latest) ├── env: Job-level environment variables ├── strategy: Matrix, fail-fast, max-parallel settings └── steps: ├── uses: Pre-built action └── run: Shell command or script ```

### File Location

All workflows must be in `.github/workflows/` directory with `.yml` or `.yaml` extension. Use kebab-case for filenames: `build-and-test.yml`, `deploy-production.yml`.

### Quick Validation

Validate YAML syntax before pushing:

```bash docker run --rm -v "$(pwd):/data" pipelinecomponents/yamllint yamllint /data/.github/workflows/ ```