---

name: caching-strategy-optimizer description: Optimizes CI/CD pipeline speed by implementing effective caching for dependencies, Docker layers, build outputs, and test results. Provides before/after performance metrics and best practices. Use for "CI caching", "pipeline optimization", "build speed", or "cache strategy".

Caching Strategy Optimizer

Dramatically speed up CI pipelines with intelligent caching.

Cache Key Strategy

Package Manager Caches

# NPM - Hash package-lock.json
- uses: actions/cache@v3
  with:
    path: ~/.npm
    key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
    restore-keys: |
      ${{ runner.os }}-npm-

# pnpm - More aggressive caching
- uses: pnpm/action-setup@v2
  with:
    version: 8

- uses: actions/cache@v3
  with:
    path: |
      ~/.pnpm-store
      node_modules
    key: ${{ runner.os }}-pnpm-${{ hashFiles('**/pnpm-lock.yaml') }}
    restore-keys: |
      ${{ runner.os }}-pnpm-

# Python pip
- uses: actions/cache@v3
  with:
    path: ~/.cache/pip
    key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}

# Cargo/Rust
- uses: actions/cache@v3
  with:
    path: |
      ~/.cargo/bin/
      ~/.cargo/registry/index/
      ~/.cargo/registry/cache/
      ~/.cargo/git/db/
      target/
    key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}

Docker Layer Caching

Using Buildx

- name: Set up Docker Buildx
  uses: docker/setup-buildx-action@v3

- name: Build with cache
  uses: docker/build-push-action@v5
  with:
    context: .
    cache-from: type=gha
    cache-to: type=gha,mode=max

Registry-based Cache

- name: Build with registry cache
  uses: docker/build-push-action@v5
  with:
    context: .
    cache-from: type=registry,ref=myapp:buildcache
    cache-to: type=registry,ref=myapp:buildcache,mode=max

Build Output Caching

# Next.js cache
- uses: actions/cache@v3
  with:
    path: |
      ${{ github.workspace }}/.next/cache
    key: ${{ runner.os }}-nextjs-${{ hashFiles('**/package-lock.json') }}-${{ hashFiles('**/*.js', '**/*.jsx', '**/*.ts', '**/*.tsx') }}
    restore-keys: |
      ${{ runner.os }}-nextjs-${{ hashFiles('**/package-lock.json') }}-
      ${{ runner.os }}-nextjs-

# Webpack cache
- uses: actions/cache@v3
  with:
    path: node_modules/.cache/webpack
    key: ${{ runner.os }}-webpack-${{ hashFiles('webpack.config.js') }}-${{ hashFiles('src/**') }}

# TypeScript build cache
- uses: actions/cache@v3
  with:
    path: |
      dist
      tsconfig.tsbuildinfo
    key: ${{ runner.os }}-tsc-${{ hashFiles('**/*.ts') }}

Test Results Caching

# Jest cache
- uses: actions/cache@v3
  with:
    path: /tmp/jest_rt
    key: ${{ runner.os }}-jest-${{ hashFiles('**/*.test.ts') }}

# Pytest cache
- uses: actions/cache@v3
  with:
    path: .pytest_cache
    key: ${{ runner.os }}-pytest-${{ hashFiles('**/*test*.py') }}

Before/After Metrics

## Before Optimization

- Total time: 12 minutes
- npm ci: 4 minutes
- Build: 5 minutes
- Tests: 3 minutes

## After Caching

- Total time: 3 minutes
- npm ci: 30 seconds (cache hit)
- Build: 1 minute (incremental)
- Tests: 1.5 minutes (cache hit)

**Improvement: 75% faster (12m → 3m)**

Cache Hit Rate Monitoring

- name: Check cache hit
  id: cache
  uses: actions/cache@v3
  with:
    path: node_modules
    key: ${{ runner.os }}-deps-${{ hashFiles('package-lock.json') }}

- name: Log cache status
  run: |
    if [ "${{ steps.cache.outputs.cache-hit }}" == "true" ]; then
      echo "✅ Cache hit - saved $(date -u -d @$SECONDS +%M:%S)"
    else
      echo "❌ Cache miss - installing from scratch"
    fi

Best Practices

1. Precise keys: Include all dependencies in hash
2. Restore keys: Fallback to partial matches
3. Multiple paths: Cache related files together
4. Size limits: GitHub Actions limit is 10GB
5. Expiration: Caches expire after 7 days
6. Mode=max: Docker cache mode for better hits
7. Monitor hits: Track cache effectiveness

Common Pitfalls

❌ Too generic keys: key: deps (always hits) ✅ Specific keys: key: deps-${{ hashFiles('package-lock.json') }}

❌ Missing restore-keys: Cache miss on minor changes ✅ Restore keys: Partial match fallback

❌ Caching node_modules with wrong lock file ✅ Match lock file: Hash the right lockfile

Output Checklist

• Package manager cache configured
• Build output cache
• Docker layer cache (if applicable)
• Test cache configured
• Cache keys use file hashes
• Restore keys for fallback
• Before/after metrics documented
• Cache hit monitoring