cache/README.md

# cache

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

<a href="https://github.com/actions/cache"><img alt="GitHub Actions status" src="https://github.com/actions/cache/workflows/Tests/badge.svg"></a>

## 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

See [Examples](examples.md)

## 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].outputs.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)