feat(m4): ADR-074 M4 — 備份還原週排程驗證 CronJob

- scripts/cron_backup_restore_test.sh: Velero restore dry-run 腳本
- k8s/awoooi-prod/16-cronjob-backup-restore-test.yaml: 每週日 02:00 台北執行
- k8s/awoooi-prod/17-configmap-backup-restore-scripts.yaml: 腳本 ConfigMap
- flywheel-alerts.yaml: BackupRestoreTestFailed + BackupRestoreTestStale 告警

失敗時寫入 node-exporter textfile → Prometheus 告警 → TYPE-3 Incident

2026-04-12 ogt (ADR-074 M4)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/cron_backup_restore_test.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+# =============================================================================
+# 備份還原驗證 CronJob — ADR-074 M4
+# =============================================================================
+# 每週日 02:00 台北執行 Velero restore dry-run，驗證 PVC 快照可讀取。
+# 失敗時寫入 Prometheus textfile metrics → 觸發 BackupRestoreTestFailed 告警。
+#
+# Textfile 路徑：/var/lib/node_exporter/textfile_collector/backup_restore_test.prom
+# （由 node-exporter --collector.textfile.directory 掃描）
+#
+# 2026-04-12 ogt (ADR-074 M4)
+# =============================================================================
+
+set -e
+
+TEXTFILE="/var/lib/node_exporter/textfile_collector/backup_restore_test.prom"
+NAMESPACE="${VELERO_NAMESPACE:-velero}"
+BACKUP_NAME="${VELERO_BACKUP_NAME:-awoooi-daily}"
+EXIT_CODE=0
+
+echo "=== backup-restore-test: $(date '+%Y-%m-%d %H:%M:%S %Z') ==="
+echo "Backup: ${BACKUP_NAME}  Namespace: ${NAMESPACE}"
+
+# --- Velero restore dry-run ---
+velero restore create \
+  --from-backup "${BACKUP_NAME}" \
+  --namespace-mappings "${NAMESPACE}:restore-test-dry" \
+  --dry-run \
+  --wait \
+  2>&1 || EXIT_CODE=$?
+
+# --- 寫入 textfile metric ---
+TS=$(date +%s%3N)
+mkdir -p "$(dirname "${TEXTFILE}")"
+
+if [ "${EXIT_CODE}" -eq 0 ]; then
+  echo "backup restore dry-run OK"
+  cat > "${TEXTFILE}" <<PROM
+# HELP awoooi_backup_restore_test_success 1 = last backup restore dry-run succeeded
+# TYPE awoooi_backup_restore_test_success gauge
+awoooi_backup_restore_test_success 1 ${TS}
+# HELP awoooi_backup_restore_test_timestamp_seconds Unix timestamp of last test run
+# TYPE awoooi_backup_restore_test_timestamp_seconds gauge
+awoooi_backup_restore_test_timestamp_seconds $(date +%s) ${TS}
+PROM
+  echo "Textfile written: success"
+  exit 0
+else
+  echo "backup restore dry-run FAILED (exit ${EXIT_CODE})"
+  cat > "${TEXTFILE}" <<PROM
+# HELP awoooi_backup_restore_test_success 1 = last backup restore dry-run succeeded
+# TYPE awoooi_backup_restore_test_success gauge
+awoooi_backup_restore_test_success 0 ${TS}
+# HELP awoooi_backup_restore_test_timestamp_seconds Unix timestamp of last test run
+# TYPE awoooi_backup_restore_test_timestamp_seconds gauge
+awoooi_backup_restore_test_timestamp_seconds $(date +%s) ${TS}
+PROM
+  echo "Textfile written: failure"
+  exit 1
+fi