cache
- Git course
- Advanced
- Lesson 42/56
- 4 min
Learn to speed up with dependency caching.
Caching dependencies
Downloading external libraries on every CI run slows down pipeline execution significantly. The actions/cache action saves downloaded package directories on GitHub runners for subsequent runs. This allows workflows to complete in seconds rather than minutes.
- uses: actions/cache@v4
with:
path: ~/.npm
key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}On a cache hit, dependencies are restored from disk without downloading again.
Cache key and restore-keys
To keep the cache fresh, a checksum of the lockfile (hashFiles) is typically included in the key parameter. If a dependency changes, the hash updates and a new cache is generated. If an exact match isn't found, restore-keys restores the closest previous cache.
with:
path: ~/.npm
key: node-cache-${{ hashFiles('package-lock.json') }}
restore-keys: |
node-cache-This structure minimizes full download overhead.
Practice Add cache step to workflow
Add the actions/cache@v4 step to the workflow with path: ~/.npm and key: npm-cache.
Starter code
cat << 'EOF' > .github/workflows/ci.yml
steps:
- uses: actions/checkout@v4
# onbellek adimini buraya ekle
EOF
cat .github/workflows/ci.ymlSample solution
cat << 'EOF' > .github/workflows/ci.yml
steps:
- uses: actions/checkout@v4
- uses: actions/cache@v4
with:
path: ~/.npm
key: npm-cache
EOF
cat .github/workflows/ci.ymlExpected output
steps:
- uses: actions/checkout@v4
- uses: actions/cache@v4
with:
path: ~/.npm
key: npm-cache
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the main benefit of using actions/cache in CI workflows?
- Automatically sharing secret keys with third parties
- Eliminating dependency download time to speed up workflows Correct answer
- Automatically marking failed tests as passed
- Permanently reducing repo size on the server
Explanation: Caching saves packages and avoids re-downloading them, significantly reducing workflow execution time.
2 Invoke cache action
- uses: actions/____@v4 - uses: actions/cache@v4Explanation: The official actions/cache@v4 action is used to cache dependencies.
3 Cache parameters
| Term | Meaning |
|---|---|
actions/cache |
Saves dependencies to speed up runs |
key |
Unique identifier of the cache |
restore-keys |
Fallback cache if no exact match |
hashFiles |
Generates hash of lockfile |