All supported package managers recommend that you **always** commit the lockfile, although implementations vary doing so generally provides the following benefits:
- Enables faster installation for CI and production environments, due to being able to skip package resolution.
- Describes a single representation of a dependency tree such that teammates, deployments, and continuous integration are guaranteed to install exactly the same dependencies.
- Provides a facility for users to "time-travel" to previous states of `node_modules` without having to commit the directory itself.
- Facilitates greater visibility of tree changes through readable source control diffs.
In order to get the most out of using your lockfile on continuous integration follow the conventions outlined below for your respective package manager.
### NPM
Ensure that `package-lock.json` is always committed, use `npm ci` instead of `npm install` when installing packages.
The `check-latest` flag defaults to `false`. When set to `false`, the action will first check the local cache for a semver match. If unable to find a specific version in the cache, the action will attempt to download a version of Node.js. It will pull LTS versions from [node-versions releases](https://github.com/actions/node-versions/releases) and on miss or failure will fall back to the previous behavior of downloading directly from [node dist](https://nodejs.org/dist/). Use the default or set `check-latest` to `false` if you prefer stability and if you want to ensure a specific version of Node.js is always used.
If `check-latest` is set to `true`, the action first checks if the cached version is the latest one. If the locally cached version is not the most up-to-date, a version of Node.js will then be downloaded. Set `check-latest` to `true` it you want the most up-to-date version of Node.js to always be used.
> Setting `check-latest` to `true` has performance implications as downloading versions of Node is slower than using cached versions.
The `node-version-file` input accepts a path to a file containing the version of Node.js to be used by a project, for example `.nvmrc`, `.node-version` or `.tool-versions`. If both the `node-version` and the `node-version-file` inputs are provided then the `node-version` input is used.
You can use any of the [supported operating systems](https://docs.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners), and the compatible `architecture` can be selected using `architecture`. Values are `x86`, `x64`, `arm64`, `armv6l`, `armv7l`, `ppc64le`, `s390x` (not all of the architectures are available on all platforms).
When using `architecture`, `node-version` must be provided as well.
The action follows [actions/cache](https://github.com/actions/cache/blob/main/examples.md#node---npm) guidelines, and caches global cache on the machine instead of `node_modules`, so cache can be reused between different Node.js versions.
Yarn2 ignores both .npmrc and .yarnrc files created by the action, so before installing dependencies from the private repo it is necessary either to create or to modify existing yarnrc.yml file with `yarn config set` commands.
NOTE: As per https://github.com/actions/setup-node/issues/49 you cannot use `secrets.GITHUB_TOKEN` to access private GitHub Packages within the same organisation but in a different repository.