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

• Precise keys: Include all dependencies in hash

• Restore keys: Fallback to partial matches

• Multiple paths: Cache related files together

• Size limits: GitHub Actions limit is 10GB

• Expiration: Caches expire after 7 days

• Mode=max: Docker cache mode for better hits

• 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