Turborepo Caching Strategies

Turborepo Caching Strategies

Local caching, remote caching, cache invalidation, and optimization techniques.

Local Caching

How It Works

Turborepo caches task outputs based on inputs:

1. Hash inputs: Source files, dependencies, environment variables, config
2. Run task: If hash not in cache
3. Save outputs: Store in .turbo/cache
4. Restore on match: Instant completion on cache hit

Default cache location: ./node_modules/.cache/turbo

Cache Configuration

// turbo.json
{
  "pipeline": {
    "build": {
      "outputs": ["dist/**", ".next/**", "!.next/cache/**"],
      "cache": true  // default
    },
    "dev": {
      "cache": false  // don't cache dev servers
    }
  }
}

Outputs Configuration

Specify what gets cached:

{
  "build": {
    "outputs": [
      "dist/**",              // All files in dist
      "build/**",             // Build directory
      ".next/**",             // Next.js output
      "!.next/cache/**",      // Exclude Next.js cache
      "storybook-static/**",  // Storybook build
      "*.tsbuildinfo"         // TypeScript build info
    ]
  }
}

Best practices:

• Include all build artifacts
• Exclude nested caches
• Include type definitions
• Include generated files

Clear Local Cache

# Remove cache directory
rm -rf ./node_modules/.cache/turbo

# Or use turbo command with --force
turbo run build --force

# Clear and rebuild
turbo run clean && turbo run build

Remote Caching

Share cache across team and CI/CD.

Vercel Remote Cache (Recommended)

Setup:

# Login to Vercel
turbo login

# Link repository
turbo link

Use in CI:

# .github/workflows/ci.yml
env:
  TURBO_TOKEN: ${{ secrets.TURBO_TOKEN }}
  TURBO_TEAM: ${{ secrets.TURBO_TEAM }}

steps:
  - run: turbo run build test

Get tokens from Vercel dashboard:

1. Go to https://vercel.com/account/tokens
2. Create new token
3. Add as GitHub secrets

Custom Remote Cache

Configure custom remote cache server:

// .turbo/config.json
{
  "teamid": "team_xxx",
  "apiurl": "https://cache.example.com",
  "token": "your-token"
}

Or use environment variables:

export TURBO_API="https://cache.example.com"
export TURBO_TOKEN="your-token"
export TURBO_TEAM="team_xxx"

Remote Cache Verification

# Check cache status
turbo run build --output-logs=hash-only

# Output shows:
# • web:build: cache hit, replaying logs [hash]
# • api:build: cache miss, executing [hash]

Cache Signatures

Cache invalidated when these change:

1. Source Files

All tracked Git files in package:

packages/ui/
├── src/
│   ├── button.tsx     # Tracked
│   └── input.tsx      # Tracked
├── dist/              # Ignored (in .gitignore)
└── node_modules/      # Ignored

2. Package Dependencies

Changes in package.json:

{
  "dependencies": {
    "react": "18.2.0"  // Version change invalidates cache
  }
}

3. Environment Variables

Configured in pipeline:

{
  "build": {
    "env": ["NODE_ENV", "API_URL"]  // Changes invalidate cache
  }
}

4. Global Dependencies

Files affecting all packages:

{
  "globalDependencies": [
    "**/.env.*local",
    "tsconfig.json",
    ".eslintrc.js"
  ]
}

5. Task Configuration

Changes to turbo.json pipeline:

{
  "build": {
    "dependsOn": ["^build"],
    "outputs": ["dist/**"]  // Config changes invalidate cache
  }
}

Input Control

Override Input Detection

Explicitly define what affects cache:

{
  "build": {
    "inputs": [
      "src/**/*.ts",           // Include TS files
      "src/**/*.tsx",          // Include TSX files
      "!src/**/*.test.ts",     // Exclude tests
      "!src/**/*.stories.tsx", // Exclude stories
      "package.json",          // Include package.json
      "tsconfig.json"          // Include config
    ]
  }
}

Use cases:

• Exclude test files from build cache
• Exclude documentation from production builds
• Include only source files, not generated files

Global vs Package Inputs

Global inputs (affect all packages):

{
  "globalDependencies": [".env", "tsconfig.json"]
}

Package inputs (affect specific tasks):

{
  "pipeline": {
    "build": {
      "inputs": ["src/**"]
    }
  }
}

Environment Variables

Cached Environment Variables

Include in cache signature:

{
  "pipeline": {
    "build": {
      "env": [
        "NODE_ENV",           // Must match for cache hit
        "NEXT_PUBLIC_API_URL",
        "DATABASE_URL"
      ]
    }
  }
}

Cache invalidated when values change.

Pass-Through Environment Variables

Don't affect cache:

{
  "pipeline": {
    "build": {
      "passThroughEnv": [
        "DEBUG",        // Different values use same cache
        "LOG_LEVEL",
        "VERBOSE"
      ]
    }
  }
}

Use for: Debug flags, log levels, non-production settings

Global Environment Variables

Available to all tasks:

{
  "globalEnv": [
    "NODE_ENV",
    "CI",
    "VERCEL"
  ]
}

Cache Optimization Strategies

1. Granular Outputs

Define precise outputs to minimize cache size:

// ❌ Bad - caches too much
{
  "build": {
    "outputs": ["**"]
  }
}

// ✅ Good - specific outputs
{
  "build": {
    "outputs": ["dist/**", "!dist/**/*.map"]
  }
}

2. Exclude Unnecessary Files

{
  "build": {
    "outputs": [
      ".next/**",
      "!.next/cache/**",      // Exclude Next.js cache
      "!.next/server/**/*.js.map",  // Exclude source maps
      "!.next/static/**/*.map"
    ]
  }
}

3. Separate Cacheable Tasks

{
  "pipeline": {
    "build": {
      "dependsOn": ["^build"],
      "cache": true
    },
    "test": {
      "dependsOn": ["build"],
      "cache": true  // Separate from build
    },
    "dev": {
      "cache": false  // Never cache
    }
  }
}

4. Use Input Filters

Only track relevant files:

{
  "build": {
    "inputs": [
      "src/**/*.{ts,tsx}",
      "!src/**/*.{test,spec}.{ts,tsx}",
      "public/**",
      "package.json"
    ]
  }
}

Cache Analysis

Inspect Cache Hits/Misses

# Dry run with JSON output
turbo run build --dry-run=json | jq '.tasks[] | {package: .package, task: .task, cache: .cache}'

View Task Graph

# Generate task graph
turbo run build --graph

# Output: graph.html (open in browser)

Cache Statistics

# Run with summary
turbo run build --summarize

# Output: .turbo/runs/[hash].json

CI/CD Cache Configuration

GitHub Actions

name: CI
on: [push, pull_request]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 18

      - name: Install dependencies
        run: npm install

      - name: Build and test
        run: turbo run build test lint
        env:
          TURBO_TOKEN: ${{ secrets.TURBO_TOKEN }}
          TURBO_TEAM: ${{ secrets.TURBO_TEAM }}

      # Optional: Cache node_modules
      - uses: actions/cache@v3
        with:
          path: node_modules
          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}

GitLab CI

image: node:18

cache:
  key: ${CI_COMMIT_REF_SLUG}
  paths:
    - node_modules/
    - .turbo/

build:
  stage: build
  script:
    - npm install
    - turbo run build test
  variables:
    TURBO_TOKEN: $TURBO_TOKEN
    TURBO_TEAM: $TURBO_TEAM

Troubleshooting

Cache Not Working

Check outputs are defined:

turbo run build --dry-run=json | jq '.tasks[] | {task: .task, outputs: .outputs}'

Verify cache location:

ls -la ./node_modules/.cache/turbo

Check environment variables:

echo $TURBO_TOKEN
echo $TURBO_TEAM

Cache Too Large

Analyze cache size:

du -sh ./node_modules/.cache/turbo

Reduce outputs:

{
  "build": {
    "outputs": [
      "dist/**",
      "!dist/**/*.map",      // Exclude source maps
      "!dist/**/*.test.js"   // Exclude test files
    ]
  }
}

Clear old cache:

# Turborepo doesn't auto-clean, manually remove:
rm -rf ./node_modules/.cache/turbo

Remote Cache Connection Issues

Test connection:

curl -I https://cache.example.com

Verify token:

turbo link
# Should show: "Remote caching enabled"

Check logs:

turbo run build --output-logs=full

Best Practices

1. Define precise outputs - Only cache necessary files
2. Exclude nested caches - Don't cache caches (.next/cache)
3. Use remote caching - Share cache across team and CI
4. Track relevant inputs - Use inputs to filter files
5. Separate env vars - Use passThroughEnv for debug flags
6. Cache test results - Include coverage in outputs
7. Don't cache dev servers - Set cache: false for dev tasks
8. Use global dependencies - Share config across packages
9. Monitor cache performance - Use --summarize to analyze
10. Clear cache periodically - Remove stale cache manually

Cache Performance Tips

For CI/CD:

• Enable remote caching
• Run only changed packages: --filter='...[origin/main]'
• Use --continue to see all errors
• Cache node_modules separately

For Local Development:

• Keep local cache enabled
• Don't force rebuild unless needed
• Use filters to build only what changed
• Clear cache if issues arise

For Large Monorepos:

• Use granular outputs
• Implement input filters
• Monitor cache size regularly
• Consider cache size limits on remote cache