cache/README.md

# cache

This GitHub Action allows caching dependencies and build outputs to improve workflow execution time.

## Usage

### Pre-requisites
Create a workflow `.yml` file in your repositories `.github/workflows` directory. An [example workflow](#example-workflow) is available below. For more information, reference the GitHub Help Documentation for [Creating a workflow file](https://help.github.com/en/articles/configuring-a-workflow#creating-a-workflow-file).

### Inputs

* `path` - A directory to store and save the cache
* `key` - An explicit key for restoring and saving the cache
* `restore-keys` - An ordered list of keys to use for restoring the cache if no cache hit occurred for key

### Outputs

* `cache-hit` - A boolean value to indicate an exact match was found for the key

> See [Skipping steps based on cache-hit](#Skipping-steps-based-on-cache-hit) for info on using this output

### Example workflow

```yaml
name: Example Caching with npm

on: push

jobs:
  build:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v1

    - name: Cache node_modules
      uses: actions/cache@preview
      with:
        path: node_modules
        key: ${{ runner.os }}-node

    - name: Install Dependencies
      run: npm install
    
    - name: Build
      run: npm run build

    - name: Test
      run: npm run test
```
## Ecosystem Examples

### Node - npm

```yaml
- uses: actions/cache@preview
  with:
    path: node_modules
    key: ${{ runner.os }}-node
```

### Node - Yarn

```yaml
- uses: actions/cache@preview
  with:
    path: ~/.cache/yarn
    key: ${{ runner.os }}-yarn-${{ hashFiles(format('{0}{1}', github.workspace, '/yarn.lock')) }}
    restore-keys: |
      ${{ runner.os }}-yarn-
```

### C# - Nuget

```yaml
- uses: actions/cache@preview
  with:
    path: ~/.nuget/packages
    key: ${{ runner.os }}-nuget-${{ hashFiles('**/packages.lock.json') }}
    restore-keys: |
      ${{ runner.os }}-nuget-
```

### Java - Gradle

```yaml
- uses: actions/cache@preview
  with:
    path: ~/.gradle/caches
    key: gradle-${{ runner.os }}-${{ hashFiles('**/*.gradle') }}
    restore-keys: |
      gradle-${{ runner.os }}-
```

### Java - Maven
```yaml
- uses: actions/cache@preview
  with:
    path: ~/.m2/repository
    key: ${{ runner.os }}-maven
```

## Cache Limits

Individual caches are limited to 200MB and a repository can have up to 2GB of caches. Once the 2GB limit is reached, older caches will be evicted based on when the cache was last accessed.

## Skipping steps based on cache-hit

Using the `cache-hit` output, subsequent steps (such as install or build) can be skipped when a cache hit occurs on the key.

Example:
```yaml
steps:
  - uses: actions/checkout@v1

  - uses: actions/cache@preview
    id: cache
    with:
      path: path/to/dependencies
      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles')}}
  
  - name: Install Dependencies
    if: steps.cache.outputs.cache-hit != 'true'
    run: /install.sh
```

> Note: The `id` defined in `actions/cache` must match the `id` in the `if` statement (i.e. `steps.[ID].outupts.cache-hit`)

## Contributing
We would love for you to contribute to `@actions/cache`, pull requests are welcome! Please see the [CONTRIBUTING.md](CONTRIBUTING.md) for more information.

## License
The scripts and documentation in this project are released under the [MIT License](LICENSE)