building-ci-pipelines

# Building CI Pipelines

## Purpose

CI/CD pipelines automate testing, building, and deploying software. This skill provides patterns for constructing robust, secure, and efficient pipelines across GitHub Actions, GitLab CI, Argo Workflows, and Jenkins. Focus areas: supply chain security (SLSA), monorepo optimization, caching, and parallelization.

## When to Use This Skill

Invoke when:
- Setting up continuous integration for new projects
- Implementing automated testing workflows
- Building container images with security provenance
- Optimizing slow CI pipelines (especially monorepos)
- Implementing SLSA supply chain security
- Configuring multi-platform builds
- Setting up GitOps automation
- Migrating from legacy CI systems

## Platform Selection

**GitHub-hosted** → GitHub Actions (SLSA native, 10K+ actions, OIDC)
**GitLab-hosted** → GitLab CI (parent-child pipelines, built-in security)
**Kubernetes** → Argo Workflows (DAG-based, event-driven)
**Legacy** → Jenkins (migrate when possible)

### Platform Comparison

| Feature | GitHub Actions | GitLab CI | Argo | Jenkins |
|---------|---------------|-----------|------|---------|
| Ease of Use | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐ |
| SLSA | Native | Manual | Good | Manual |
| Monorepo | Good | Excellent | Manual | Plugins |

## Quick Start Patterns

### Pattern 1: Basic CI (Lint → Test → Build)

```yaml
# GitHub Actions
name: CI
on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm run lint

  test:
    needs: lint
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm test

  build:
    needs: test
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm run build
```

### Pattern 2: Matrix Strategy (Multi-Platform)

```yaml
test:
  runs-on: ${{ matrix.os }}
  strategy:
    matrix:
      os: [ubuntu-latest, windows-latest, macos-latest]
      node-version: [18, 20, 22]
  steps:
    - us