fix(health): /health/ready 503 on HANA crash-loops every deploy (#2975)

srv/lib/scheduler-ready.js

@@ -21,3 +21,20 @@ export function computeReadiness({ schedulerArmed, dbOk }) {
     db: dbOk ? 'connected' : 'error',
   };
 }
+
+/**
+ * Dialect-safe liveness ping SQL for a cheap `cds.db.run(...)`.
+ *
+ * #2975 regression: HANA rejects a bare `SELECT 1` ("sql syntax error") — it
+ * requires `SELECT 1 FROM DUMMY`. SQLite rejects `FROM DUMMY`. The original
+ * /health/ready probe hardcoded `SELECT 1`, so dbOk was ALWAYS false on HANA,
+ * /health/ready stayed 503, and CF's startup health gate crash-looped the app
+ * on every deploy. (The integration test ran on in-memory SQLite, where bare
+ * `SELECT 1` works, so it never caught this.)
+ *
+ * @param {string} [kind] db kind, defaults to cds.db.kind at call sites
+ * @returns {string}
+ */
+export function dbPingSql(kind) {
+  return kind === 'hana' ? 'SELECT 1 FROM DUMMY' : 'SELECT 1';
+}

srv/server.js

@@ -105,7 +105,7 @@ import { uploadPetSubmission, decodePhotoUpload } from './lib/petoberfest-upload
 import { fetchPetPhoto } from './lib/petoberfest-photo-store.js';
 import { installDbWrap } from './lib/metrics-db-wrap.js';
 import { wireDraftIntegrityPreflight } from './lib/draft-integrity-preflight.js';
-import { isSchedulerReady, computeReadiness } from './lib/scheduler-ready.js';
+import { isSchedulerReady, computeReadiness, dbPingSql } from './lib/scheduler-ready.js';
 import './graphql-config.js';
 import { makeA2aRouter } from './lib/a2a/rpc-router.js';
 import { a2aIasAuthMiddleware } from './lib/a2a/ias-auth-mw.js';
@@ -297,7 +297,7 @@ cds.on('bootstrap', (app) => {
   app.get('/health/ready', async (req, res) => {
     let dbOk = false;
     if (cds.db) {
-      try { await cds.db.run('SELECT 1'); dbOk = true; }
+      try { await cds.db.run(dbPingSql(cds.db.kind)); dbOk = true; }
       catch (_err) { dbOk = false; }
     }
     // cds.db absent → dbOk stays false
@@ -307,7 +307,7 @@ cds.on('bootstrap', (app) => {
 
   app.get('/health/db', async (req, res) => {
     try {
-      await cds.db?.run('SELECT 1 FROM DUMMY');
+      await cds.db?.run(dbPingSql(cds.db?.kind));
       res.json({ status: 'ok', db: 'connected' });
     } catch (err) {
       console.error('[health/db]', err.message);

test/unit/srv/lib/scheduler-ready.test.js

@@ -1,5 +1,5 @@
 import { describe, it, expect, beforeEach } from 'vitest';
-import { markSchedulerReady, isSchedulerReady, _resetForTests, computeReadiness } from '../../../../srv/lib/scheduler-ready.js';
+import { markSchedulerReady, isSchedulerReady, _resetForTests, computeReadiness, dbPingSql } from '../../../../srv/lib/scheduler-ready.js';
 
 describe('scheduler-ready latch', () => {
   beforeEach(() => _resetForTests());
@@ -39,3 +39,15 @@ describe('computeReadiness', () => {
     expect(computeReadiness({ schedulerArmed: false, dbOk: false }).ready).toBe(false);
   });
 });
+
+describe('dbPingSql (#2975 HANA regression)', () => {
+  it('uses FROM DUMMY on HANA (bare SELECT 1 is a HANA syntax error)', () => {
+    expect(dbPingSql('hana')).toBe('SELECT 1 FROM DUMMY');
+  });
+  it('uses bare SELECT 1 on SQLite (FROM DUMMY is a SQLite error)', () => {
+    expect(dbPingSql('sqlite')).toBe('SELECT 1');
+  });
+  it('defaults to bare SELECT 1 when kind is undefined', () => {
+    expect(dbPingSql()).toBe('SELECT 1');
+  });
+});