setup-node/docs/adrs/0000-caching-dependencies.md

0. Caching dependencies

Date: 2021-05-21

Status: Proposed

Context

actions/setup-node is the 2nd most popular action in GitHub Actions. A lot of customers use it in conjunction with actions/cache to speed up dependencies installation.
See more examples on proper usage in actions/cache documentation.

Goals & Anti-Goals

Integration of caching functionality into actions/setup-node action will bring the following benefits for action users:

• Decrease the entry threshold for using the cache for Node.js dependencies and simplify initial configuration
• Simplify YAML pipelines because no need additional steps to enable caching
• More users will use cache for Node.js so more customers will have fast builds!

As the first stage, we will add support for NPM dependencies caching. We can consider adding the same functionality for Yarn later.

We don't pursue the goal to provide wide customization of caching in scope of actions/setup-node action. The purpose of this integration is covering ~90% of basic use-cases. If user needs flexible customization, we should advice them to use actions/cache directly.

Decision

• Add cache input parameter to actions/setup-node. For now, input will accept the following values:
  • npm - enable caching for npm dependencies
  • '' - disable caching (default value)
  • Potentially, we will be able to extend this input to support Yarn
• Cache feature will be disabled by default to make sure that we don't break existing customers. We will consider enabling cache by default in next major release (v3)
• Add optional input package-lock-path that will allow to specify path to package-lock.json file path:
  • If input is not defined, action will try to search package-lock.json or yarn.lock (npm 7.x supports yarn.lock files) files in the repository root and throw error if no one is found
  • If input contains file path, action will use the specified file
  • if input contains wildcards (like **/package-lock.json), hash of multiple files will be used
• The hash of file provided in package-lock-path input will be used as cache key (the same approach like actions/cache recommends)
• The following key cache will be used ${{ runner.os }}-npm-${{ hashFiles('<package-lock-path>') }}
• Action will cache global npm cache directory (retrieved via npm config get cache)

Example of real use-cases

Default use case when package-lock.json or yarn.lock are located in repository root:

steps:
- uses: actions/checkout@v2
- uses: actions/setup-node@v2
  with:
    node-version: '14'
    cache: npm

More flexible solution for monorepos:

steps:
- uses: actions/checkout@v2
- uses: actions/setup-node@v2
  with:
    node-version: '14'
    cache: npm
    package-lock-path: service1/yarn.lock

Release process

As soon as functionality is implemented, we will release minor update of action. No need to bump major version since there are no breaking changes for existing users. After that, we will update starter-workflows and GitHub Action documentation.