Monorepo Hook Configuration

Intermediatev1.0.0

Configure Lefthook for monorepo projects with multiple languages and packages — root-scoped commands, per-package hooks, and selective execution based on changed directories.

Content

Overview

Monorepos contain multiple packages, often in different languages. Lefthook's root filtering and glob patterns let you run the right tool for each package — TypeScript linting for the frontend, Python linting for the backend — without checking unrelated files.

How It Works

Package-Scoped Commands

yaml

# lefthook.yml
pre-commit:
  parallel: true
  commands:
    frontend-lint:
      root: "packages/frontend/"
      glob: "*.{ts,tsx}"
      run: cd packages/frontend && npx eslint {staged_files}

    frontend-format:
      root: "packages/frontend/"
      glob: "*.{ts,tsx,css,json}"
      run: cd packages/frontend && npx prettier --check {staged_files}

    backend-lint:
      root: "packages/backend/"
      glob: "*.py"
      run: cd packages/backend && ruff check {staged_files}

    backend-typecheck:
      root: "packages/backend/"
      glob: "*.py"
      run: cd packages/backend && mypy {staged_files}

    infra-scan:
      root: "infrastructure/"
      glob: "*.tf"
      run: checkov -f {staged_files}

    shared-secrets:
      run: gitleaks protect --staged --no-banner

Using lefthook-local.yml for Developer Overrides

yaml

# lefthook-local.yml (gitignored — personal overrides)
pre-commit:
  commands:
    frontend-lint:
      skip: true  # I'm only working on backend today

Pre-Push with Package-Specific Tests

yaml

pre-push:
  parallel: true
  commands:
    frontend-test:
      root: "packages/frontend/"
      glob: "*.{ts,tsx}"
      run: cd packages/frontend && npm test -- --passWithNoTests

    backend-test:
      root: "packages/backend/"
      glob: "*.py"
      run: cd packages/backend && pytest --tb=short

    e2e-test:
      root: "packages/e2e/"
      glob: "*.spec.ts"
      run: cd packages/e2e && npx playwright test --reporter=list

Best Practices

-Use root to scope commands to specific packages
-Run all package checks in parallel — they are independent
-Include a shared secrets scan that runs on all files
-Use lefthook-local.yml (gitignored) for developer-specific overrides
-Group related commands by package for clarity
-Only run tests for packages with changed files

Common Mistakes

-Running all linters on all files (ESLint on Python, Ruff on TypeScript)
-Not using root scoping (commands see files from wrong directory)
-Sequential execution in monorepos (each package check adds latency)
-Not providing lefthook-local.yml for developer customization

FAQ

Discussion

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How It Works

Package-Scoped Commands

yaml

# lefthook.yml
pre-commit:
  parallel: true
  commands:
    frontend-lint:
      root: "packages/frontend/"
      glob: "*.{ts,tsx}"
      run: cd packages/frontend && npx eslint {staged_files}

    frontend-format:
      root: "packages/frontend/"
      glob: "*.{ts,tsx,css,json}"
      run: cd packages/frontend && npx prettier --check {staged_files}

    backend-lint:
      root: "packages/backend/"
      glob: "*.py"
      run: cd packages/backend && ruff check {staged_files}

    backend-typecheck:
      root: "packages/backend/"
      glob: "*.py"
      run: cd packages/backend && mypy {staged_files}

    infra-scan:
      root: "infrastructure/"
      glob: "*.tf"
      run: checkov -f {staged_files}

    shared-secrets:
      run: gitleaks protect --staged --no-banner

Using lefthook-local.yml for Developer Overrides

yaml

# lefthook-local.yml (gitignored — personal overrides)
pre-commit:
  commands:
    frontend-lint:
      skip: true  # I'm only working on backend today

Pre-Push with Package-Specific Tests

yaml

pre-push:
  parallel: true
  commands:
    frontend-test:
      root: "packages/frontend/"
      glob: "*.{ts,tsx}"
      run: cd packages/frontend && npm test -- --passWithNoTests

    backend-test:
      root: "packages/backend/"
      glob: "*.py"
      run: cd packages/backend && pytest --tb=short

    e2e-test:
      root: "packages/e2e/"
      glob: "*.spec.ts"
      run: cd packages/e2e && npx playwright test --reporter=list

Best Practices

-Use root to scope commands to specific packages

-Run all package checks in parallel — they are independent

-Include a shared secrets scan that runs on all files

-Use lefthook-local.yml (gitignored) for developer-specific overrides

-Group related commands by package for clarity

-Only run tests for packages with changed files