Subject: Re: [PATCH v2 1/2] ci: skip GitHub workflow runs for already-tested commits/trees

From: SZEDER Gábor <[email-masked]>
Date: Fri, 9 Oct 2020 09:29:22 +0200

On Thu, Oct 08, 2020 at 03:29:34PM +0000, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <[email-masked]>
> 
> When pushing a commit that has already passed a CI or PR build
> successfully, it makes sense to save some energy and time and skip the
> new build.
> 
> Let's teach our GitHub workflow to do that.
> 
> For good measure, we also compare the tree ID, which is what we actually
> test (the commit ID might have changed due to a reworded commit message,
> which should not affect the outcome of the run).

We have been doing this on Travis CI for a few years now.  Does that
approach not work on GitHub actions?  Please explain in the commit
message why a different approach is taken here.

> Signed-off-by: Johannes Schindelin <[email-masked]>
> ---
>  .github/workflows/main.yml | 39 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
> index 5bd321e5e1..7391b46d61 100644
> --- a/.github/workflows/main.yml
> +++ b/.github/workflows/main.yml
> @@ -9,7 +9,7 @@ jobs:
>    ci-config:
>      runs-on: ubuntu-latest
>      outputs:
> -      enabled: ${{ steps.check-ref.outputs.enabled }}
> +      enabled: ${{ steps.check-ref.outputs.enabled }}${{ steps.skip-if-redundant.outputs.enabled }}
>      steps:
>        - name: try to clone ci-config branch
>          continue-on-error: true
> @@ -35,6 +35,43 @@ jobs:
>              enabled=no
>            fi
>            echo "::set-output name=enabled::$enabled"
> +      - name: skip if the commit or tree was already tested
> +        id: skip-if-redundant
> +        uses: actions/github-script@v3
> +        if: steps.check-ref.outputs.enabled == 'yes'
> +        with:
> +          github-token: ${{secrets.GITHUB_TOKEN}}
> +          script: |
> +            // Figure out workflow ID, commit and tree
> +            const { data: run } = await github.actions.getWorkflowRun({
> +              owner: context.repo.owner,
> +              repo: context.repo.repo,
> +              run_id: context.runId,
> +            });
> +            const workflow_id = run.workflow_id;
> +            const head_sha = run.head_sha;
> +            const tree_id = run.head_commit.tree_id;
> +
> +            // See whether there is a successful run for that commit or tree
> +            const { data: runs } = await github.actions.listWorkflowRuns({
> +              owner: context.repo.owner,
> +              repo: context.repo.repo,
> +              per_page: 500,
> +              status: 'success',
> +              workflow_id,
> +            });
> +            for (const run of runs.workflow_runs) {
> +              if (head_sha === run.head_sha) {
> +                core.warning(`Successful run for the commit ${head_sha}: ${run.html_url}`);
> +                core.setOutput('enabled', ' but skip');
> +                break;
> +              }
> +              if (tree_id === run.head_commit.tree_id) {
> +                core.warning(`Successful run for the tree ${tree_id}: ${run.html_url}`);
> +                core.setOutput('enabled', ' but skip');
> +                break;
> +              }
> +            }
>  
>    windows-build:
>      needs: ci-config
> -- 
> gitgitgadget
>