toolkit/docs/action-versioning.md

Versioning

Actions are downloaded and run from the GitHub graph of repos. The workflow references an action use a ref.

Examples:

steps:
    - use: actions/setup-node@74bc508
    - user: actions/setup-node@v1
    - uses: actions/setup-node@master

Binding to the immutable sha1 of a released version is the safest for stability and security.

Binding to a specific major version allows for receiving critical fixes and security patches while still mainting compatibility and the assurance your workflow should still work.

Binding to master is convenient but if a new major version is release which breaks compatilibility, your workflow could break.

Recommendations

1. Create a release: use sematic versioning for the release (v1.0.9)
2. Update the major version tag: move the major version tag (v1, v2, etc.) to point to the ref of the current release.
3. Compaitbility Breaks: introduce a new major version tag (v2) if changes will break existing workflows. For example, changing inputs.

See Git-Basics-Tagging