Caching Dependencies for Faster Builds

Dependency Caching in GitHub Actions

Caching dependencies between workflow runs can dramatically reduce build times — from minutes to seconds for dependency installation. GitHub Actions offers multiple caching approaches depending on your package manager.

Built-in Cache (Recommended)

Most setup actions include built-in caching:

- uses: actions/setup-node@v4
  with:
    node-version: 20
    cache: 'npm'  # or 'yarn' or 'pnpm'

Manual Cache with actions/cache

For more control, use actions/cache@v4 directly:

- name: Cache node_modules
  uses: actions/cache@v4
  with:
    path: node_modules
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
    restore-keys: |
      ${{ runner.os }}-node-

- name: Install dependencies
  run: npm ci

How Cache Keys Work

The cache system matches keys in order:

1. Exact match: runner.os-node-abc123 — full cache hit, skip install entirely
2. Prefix match (restore-keys): runner.os-node- — partial hit, restore closest match then install only changes
3. No match: Cold start, install everything from scratch

Framework-Specific Examples

Python with pip:

- uses: actions/cache@v4
  with:
    path: ~/.cache/pip
    key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}

Gradle:

- uses: actions/cache@v4
  with:
    path: |
      ~/.gradle/caches
      ~/.gradle/wrapper
    key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}

Cache Limits

• Maximum cache size per repository: 10 GB
• Caches not accessed in 7 days are automatically evicted
• When the limit is reached, the oldest caches are removed first
• Each cache entry can be up to 10 GB

Performance Impact

Typical time savings with caching:

• npm/yarn: 30-120 seconds saved per run
• pip: 15-60 seconds saved
• Gradle/Maven: 60-300 seconds saved