Add post-merge PR comment with merge-specific run links.

When a PR merges to main/master, poll for CircleCI and GitHub Actions runs created for that merge commit SHA and comment direct links on the merged PR.

Author: Alex Southwell

.github/workflows/comment-post-merge-run-links.yml

@@ -0,0 +1,170 @@
+name: Comment Post-Merge Run Links
+
+on:
+  pull_request_target:
+    types:
+      - closed
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  comment-run-links:
+    name: Comment links after merge
+    if: github.event.pull_request.merged == true && (github.event.pull_request.base.ref == 'main' || github.event.pull_request.base.ref == 'master')
+    runs-on: ${{ fromJSON(vars.GHA_RUNS_ON_JSON || '["self-hosted","linux"]') }}
+    steps:
+      - name: Resolve run links for this merge commit
+        id: resolve-links
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CIRCLECI_TOKEN: ${{ secrets.CIRCLECI_TOKEN }}
+          REPO_OWNER: ${{ github.repository_owner }}
+          REPO_NAME: ${{ github.event.repository.name }}
+          RAW_MERGE_SHA: ${{ github.event.pull_request.merge_commit_sha }}
+          RAW_BASE_REF: ${{ github.event.pull_request.base.ref }}
+          MAX_ATTEMPTS: "36"
+          SLEEP_SECONDS: "10"
+          WORKFLOW_NAME_REGEX: ${{ vars.WORKFLOW_NAME_REGEX || 'pulumi|deploy|build' }}
+          WORKFLOW_OWNER_REPO: ${{ vars.WORKFLOW_OWNER_REPO || github.repository }}
+          CIRCLECI_PROJECT_SLUG: ${{ vars.CIRCLECI_PROJECT_SLUG || '' }}
+        run: |
+          set -euo pipefail
+
+          echo "workflow_url=" >> "$GITHUB_OUTPUT"
+          echo "circleci_url=" >> "$GITHUB_OUTPUT"
+          echo "notes=" >> "$GITHUB_OUTPUT"
+          echo "merge_sha=n/a" >> "$GITHUB_OUTPUT"
+          echo "base_ref=n/a" >> "$GITHUB_OUTPUT"
+
+          # Validate event values before using them in API requests.
+          if [[ "${RAW_BASE_REF}" != "main" && "${RAW_BASE_REF}" != "master" ]]; then
+            echo "notes=Unsupported base branch; expected main/master." >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          if [[ ! "${RAW_MERGE_SHA}" =~ ^[0-9a-f]{40}$ ]]; then
+            echo "notes=No valid merge commit SHA available on this PR event." >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          BASE_REF="${RAW_BASE_REF}"
+          MERGE_SHA="${RAW_MERGE_SHA}"
+          echo "merge_sha=${MERGE_SHA}" >> "$GITHUB_OUTPUT"
+          echo "base_ref=${BASE_REF}" >> "$GITHUB_OUTPUT"
+
+          attempt=1
+          workflow_url=""
+          while [[ $attempt -le ${MAX_ATTEMPTS} ]]; do
+            runs_json="$(gh api "/repos/${WORKFLOW_OWNER_REPO}/actions/runs?event=push&head_sha=${MERGE_SHA}&per_page=50" 2>/dev/null || true)"
+            workflow_url="$(RUNS_JSON="${runs_json}" BASE_REF="${BASE_REF}" WORKFLOW_NAME_REGEX="${WORKFLOW_NAME_REGEX}" python3 - <<'PY_INNER'
+import json
+import os
+import re
+
+raw = os.environ.get("RUNS_JSON") or "{}"
+base_ref = os.environ.get("BASE_REF") or ""
+name_re = os.environ.get("WORKFLOW_NAME_REGEX") or "pulumi|deploy|build"
+
+try:
+    data = json.loads(raw)
+except Exception:
+    print("")
+    raise SystemExit(0)
+
+runs = data.get("workflow_runs") or []
+if not runs:
+    print("")
+    raise SystemExit(0)
+
+def branch_ok(run):
+    branch = (run.get("head_branch") or "")
+    return (not base_ref) or (branch == base_ref)
+
+regex = re.compile(name_re, re.IGNORECASE)
+filtered = [r for r in runs if branch_ok(r)]
+preferred = [r for r in filtered if regex.search(r.get("name") or "")]
+
+candidate = None
+if preferred:
+    candidate = sorted(preferred, key=lambda x: x.get("run_number", 0), reverse=True)[0]
+elif filtered:
+    candidate = sorted(filtered, key=lambda x: x.get("run_number", 0), reverse=True)[0]
+
+print((candidate or {}).get("html_url", ""))
+PY_INNER
+)"
+            if [[ -n "${workflow_url}" ]]; then
+              break
+            fi
+            sleep "${SLEEP_SECONDS}"
+            attempt=$(( attempt + 1 ))
+          done
+
+          if [[ -n "${workflow_url}" ]]; then
+            echo "workflow_url=${workflow_url}" >> "$GITHUB_OUTPUT"
+          fi
+
+          circleci_slug="${CIRCLECI_PROJECT_SLUG}"
+          if [[ -z "${circleci_slug}" ]]; then
+            circleci_slug="${REPO_OWNER}/${REPO_NAME}"
+          fi
+
+          if [[ -z "${CIRCLECI_TOKEN:-}" ]]; then
+            echo "notes=CircleCI token not configured; skipping CircleCI run lookup." >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          attempt=1
+          circleci_url=""
+          while [[ $attempt -le ${MAX_ATTEMPTS} ]]; do
+            pipelines_json="$(curl -fsSL -H "Circle-Token: ${CIRCLECI_TOKEN}" "https://circleci.com/api/v2/project/gh/${circleci_slug}/pipeline?branch=${BASE_REF}" 2>/dev/null || true)"
+            circleci_url="$(PIPELINES_JSON="${pipelines_json}" CIRCLECI_SLUG="${circleci_slug}" MERGE_SHA="${MERGE_SHA}" python3 - <<'PY_INNER'
+import json
+import os
+
+raw = os.environ.get("PIPELINES_JSON") or "{}"
+slug = os.environ.get("CIRCLECI_SLUG") or ""
+merge_sha = os.environ.get("MERGE_SHA") or ""
+
+try:
+    data = json.loads(raw)
+except Exception:
+    print("")
+    raise SystemExit(0)
+
+for item in data.get("items") or []:
+    vcs = item.get("vcs") or {}
+    if (vcs.get("revision") or "") == merge_sha:
+        number = item.get("number")
+        if number is not None:
+            print(f"https://app.circleci.com/pipelines/github/{slug}/{number}")
+            raise SystemExit(0)
+
+print("")
+PY_INNER
+)"
+            if [[ -n "${circleci_url}" ]]; then
+              break
+            fi
+            sleep "${SLEEP_SECONDS}"
+            attempt=$(( attempt + 1 ))
+          done
+
+          if [[ -n "${circleci_url}" ]]; then
+            echo "circleci_url=${circleci_url}" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Add run links to merged PR
+        uses: peter-evans/create-or-update-comment@v4
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          body: |
+            Merged to `${{ steps.resolve-links.outputs.base_ref }}`.
+
+            Follow-on runs for merge commit `${{ steps.resolve-links.outputs.merge_sha }}`:
+
+            - CircleCI: ${{ steps.resolve-links.outputs.circleci_url || 'Not found within polling window.' }}
+            - GitHub Actions workflow: ${{ steps.resolve-links.outputs.workflow_url || 'Not found within polling window.' }}
+
+            ${{ steps.resolve-links.outputs.notes }}