0001-support-caching-deps-for-monorepos.md

0. Support caching dependencies for mono repos

Date: 2021-07-13

Status: Proposed

Context

Currently, actions/setup-node supports caching dependencies for Npm and Yarn package managers.
For the first iteration, we have decided to not support cases where package-lock.json / yarn.lock are located outside of repository root.
Current implementation searches the following file patterns in the repository root: package-lock.json, yarn.lock (in order of resolving priorities)

Obviously, it made build-in caching unusable for mono-repos and repos with complex structure.
We would like to revisit this decision and add customization for dependencies lock file location.

Proposal

We have the following options:

1. Allow to specify directory where package-lock.json or yarn.lock are located
2. Allow to specify path to the dependencies lock file (including directory path and filename)

The second option looks more generic because it allows to:

• specify multiple dependencies files using file patterns like **/package-lock.json (one of recommended approaches in actions/cache)
• specify custom dependencies files like src/npm-shrinkwrap.json
• change default resolving priority if both yarn.lock and package-lock.json exist in repository

Decision

Add cache-dependency-path input that will accept path (relative to repository root) to dependencies lock file.
If provided path contains wildcards, the action will search all maching files and calculate common hash like ${{ hashFiles('**/package-lock.json') }} YAML construction does.
The hash of provided matched files will be used as a part of cache key.

Yaml examples:

steps:
- uses: actions/checkout@v2
- uses: actions/setup-node@v2
  with:
    node-version: 14
    cache: npm
    cache-dependency-path: 'sub-project/package-lock.json'

steps:
- uses: actions/checkout@v2
- uses: actions/setup-node@v2
  with:
    node-version: 14
    cache: yarn
    cache-dependency-path: 'sub-project/**/yarn.lock'