add the PR annotate-r workflow

.github/workflows/annotate.yml

@@ -0,0 +1,63 @@
+name: Annotate pull request with regression summaries
+# Takes a regression summary from a workflow run and annotates the pull request with it
+# The pull request number is taken from the first line of the summary.txt file.
+# The summary file is in an artifact called regression_summary associated
+# with the workflow run that triggered this workflow.
+# based on https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#using-data-from-the-triggering-workflow
+
+on:
+  workflow_run:
+    workflows:
+      - Continuous Integration
+    types:
+      - completed
+
+run-name: Annotate "${{ github.event.workflow_run.display_title }}"
+
+jobs:
+  on-success:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.event == 'pull_request' }}
+    steps:
+      - run: echo 'The triggering workflow passed'
+      - name: 'Download regression_summary artifact'
+        uses: actions/github-script@v6
+        with:
+          script: |
+            let allArtifacts = await github.rest.actions.listWorkflowRunArtifacts({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              run_id: context.payload.workflow_run.id,
+            });
+            let matchArtifact = allArtifacts.data.artifacts.filter((artifact) => {
+              return artifact.name == "regression_summary"
+            })[0];
+            let download = await github.rest.actions.downloadArtifact({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              artifact_id: matchArtifact.id,
+              archive_format: 'zip',
+            });
+            let fs = require('fs');
+            fs.writeFileSync(`${process.env.GITHUB_WORKSPACE}/regression_summary.zip`, Buffer.from(download.data));
+
+      - name: 'Unzip artifact'
+        run: unzip regression_summary.zip
+
+      - name: 'Get pull request number'
+        run: |
+          echo "PR_NUMBER=$( head -n 1 summary.txt )" >> $GITHUB_ENV
+          # remove the first line from the file
+          sed -i '1d' summary.txt
+
+      - name: Write summary to pull request as a comment
+        uses: thollander/actions-comment-pull-request@v2
+        with:
+          filePath: summary.txt
+          pr_number: ${{ env.PR_NUMBER }}
+
+      - name: Report the github.event.workflow_run as json
+        if: ${{ failure() }}
+        run: echo $JSON
+        env:
+          JSON: ${{ toJson(github.event.workflow_run) }}