Doc-only PRs skip required CI jobs to save time, but doesn't allow merge

[tomvothecoder]

In .github/workflows/build_workflow.yml, it specifies path-ignores: ["docs/**"] for PRs (https://github.com/E3SM-Project/e3sm_diags/blob/master/.github/workflows/build_workflow.yml#L10). This means that CI jobs are skipped for PRs with doc-only changes, which saves resources and time since doc-only changes do not affect the build.

However, the skipped jobs are required in order to merge the build. This is an ongoing requested GitHub feature to allow doc-only PRs be merged and bypass the required checks.

Related posts:

• https://bugs.python.org/issue40548
• https://github.saobby.my.eu.orgmunity/t/feature-request-conditional-required-checks/16761/13

Possible solution: https://github.com/marketplace/actions/skip-duplicate-actions#skip-ignored-paths

In many projects, it is unnecessary to run all tests for documentation-only-changes. Therefore, GitHub provides a paths-ignore feature out of the box. However, GitHub's paths-ignore has some limitations:

• GitHub's paths-ignore fails to look at previous commits. This means that the outcome depends on how often you push changes.
• Consequently, GitHub's paths-ignore does not work for required checks. If you path-ignore a required check, then pull requests will block forever without being mergeable.

To overcome those limitations, skip-duplicate-actions provides a more flexible paths_ignore-feature with an efficient backtracking-algorithm. Instead of stupidly looking at the current commit, paths_ignore will look for successful checks in your commit-history.