Upstream libc++ buildbot restarter.

.github/workflows/restart-preempted-libcxx-jobs.yaml

@@ -0,0 +1,109 @@
+name: Restart Preempted Libc++ Workflow
+
+# The libc++ builders run on preemptable VMs, which can be shutdown at any time.
+# This workflow identifies when a workflow run was canceled due to the VM being preempted,
+# and restarts the workflow run.
+
+# We identify a canceled workflow run by checking the annotations of the check runs in the check suite,
+# which should contain the message "The runner has received a shutdown signal."
+
+# Note: If a job is both preempted and also contains a non-preemption failure, we do not restart the workflow.
+
+on:
+  workflow_run:
+    workflows:
+      - "Build and Test libc\+\+"
+    types:
+      - failure
+      - canceled
+
+permissions:
+  contents: read
+
+jobs:
+  restart:
+    if: github.repository_owner == 'llvm'
+    name: "Restart Job"
+    permissions:
+      statuses: read
+      checks: read
+      actions: write
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Restart Job"
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea #v7.0.1
+        with:
+          script: |
+            const failure_regex = /Process completed with exit code 1./
+            const preemption_regex = /The runner has received a shutdown signal/
+
+            console.log('Listing check runs for suite')
+            const check_suites = await github.rest.checks.listForSuite({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              check_suite_id: context.payload.workflow_run.check_suite_id
+            })
+
+            check_run_ids = [];
+            for (check_run of check_suites.data.check_runs) {
+              console.log('Checking check run: ' + check_run.id);
+              console.log(check_run);
+              if (check_run.status != 'completed') {
+                console.log('Check run was not completed. Skipping.');
+                continue;
+              }
+              if (check_run.conclusion != 'failure' && check_run.conclusion != 'cancelled') {
+                console.log('Check run had conclusion: ' + check_run.conclusion + '. Skipping.');
+                continue;
+              }
+              check_run_ids.push(check_run.id);
+            }
+
+            has_preempted_job = false;
+
+            for (check_run_id of check_run_ids) {
+              console.log('Listing annotations for check run: ' + check_run_id);
+
+              annotations = await github.rest.checks.listAnnotations({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                check_run_id: check_run_id
+              })
+
+              console.log(annotations);
+              for (annotation of annotations.data) {
+                if (annotation.annotation_level != 'failure') {
+                  continue;
+                }
+
+                const preemption_match = annotation.message.match(preemption_regex);
+
+                if (preemption_match != null) {
+                  console.log('Found preemption message: ' + annotation.message);
+                  has_preempted_job = true;
+                }
+
+                const failure_match = annotation.message.match(failure_regex);
+                if (failure_match != null) {
+                  // We only want to restart the workflow if all of the failures were due to preemption.
+                  // We don't want to restart the workflow if there were other failures.
+                  console.log('Choosing not to rerun workflow because we found a non-preemption failure');
+                  console.log('Failure message: ' + annotation.message);
+                  return;
+                }
+              }
+            } 
+
+            if (!has_preempted_job) {
+              console.log('No preempted jobs found. Not restarting workflow.');
+              return;
+            }
+
+            console.log("Restarted workflow: " + context.payload.workflow_run.id);
+            await github.rest.actions.reRunWorkflowFailedJobs({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                run_id: context.payload.workflow_run.id
+              })
+
+