Cover health endpoint env activation

Author: justin808

docs/oss/building-features/node-renderer/health-checks.md

@@ -124,7 +124,10 @@ gating readiness on `/ready` deadlocks the rollout: no traffic → no first rend
 
 Only use `/ready` as the readiness gate when something other than probe-gated traffic delivers the first render,
 for example a deployment pipeline step or Rails initializer that POSTs a warm-up render to each new replica
-directly (bypassing the Service), or a container `postStart` hook that does the same. With a warm-up path in place:
+directly (bypassing the Service), or a container `postStart` hook that does the same. That warm-up must reach
+every renderer worker that can answer probes; with `workersCount > 1`, one render per replica is not enough
+unless you intentionally run a single worker or fan out warm-up renders to each worker. With a warm-up path in
+place:
 
 ```yaml
 readinessProbe:

packages/react-on-rails-pro-node-renderer/src/shared/configBuilder.ts

@@ -410,6 +410,7 @@ export function buildConfig(providedUserConfig?: Partial<Config>): Config {
     password: env.RENDERER_PASSWORD,
     // Re-evaluate env-derived defaults at build time in case env vars are set post-import.
     replayServerAsyncOperationLogs: defaultReplayServerAsyncOperationLogs(),
+    enableHealthEndpoints: truthy(env.RENDERER_ENABLE_HEALTH_ENDPOINTS),
   };
   config = { ...runtimeDefaultConfig, ...userConfig };
   if (explicitUndefinedPassword) {

packages/react-on-rails-pro-node-renderer/tests/healthEndpoints.test.ts

@@ -25,6 +25,7 @@ const testName = 'healthEndpoints';
 const gemVersion = packageJson.version;
 const { protocolVersion } = packageJson;
 const railsEnv = 'test';
+const originalEnableHealthEndpointsEnv = process.env.RENDERER_ENABLE_HEALTH_ENDPOINTS;
 
 disableHttp2();
 
@@ -58,6 +59,7 @@ describe('built-in health endpoints', () => {
   let app: ReturnType<typeof createWorker> | undefined;
 
   beforeEach(async () => {
+    delete process.env.RENDERER_ENABLE_HEALTH_ENDPOINTS;
     await resetForTest(testName);
   });
 
@@ -67,6 +69,11 @@ describe('built-in health endpoints', () => {
   });
 
   afterAll(async () => {
+    if (originalEnableHealthEndpointsEnv === undefined) {
+      delete process.env.RENDERER_ENABLE_HEALTH_ENDPOINTS;
+    } else {
+      process.env.RENDERER_ENABLE_HEALTH_ENDPOINTS = originalEnableHealthEndpointsEnv;
+    }
     await resetForTest(testName);
   });
 
@@ -90,6 +97,19 @@ describe('built-in health endpoints', () => {
     expect(JSON.parse(res.payload)).toEqual({ status: 'ok' });
   });
 
+  test('GET /health and GET /ready are registered when enabled by environment variable', async () => {
+    process.env.RENDERER_ENABLE_HEALTH_ENDPOINTS = 'true';
+    app = createWorker();
+
+    const healthRes = await app.inject().get('/health').end();
+    expect(healthRes.statusCode).toBe(200);
+    expect(JSON.parse(healthRes.payload)).toEqual({ status: 'ok' });
+
+    const readyRes = await app.inject().get('/ready').end();
+    expect(readyRes.statusCode).toBe(503);
+    expect(JSON.parse(readyRes.payload)).toEqual({ status: 'waiting_for_bundle' });
+  });
+
   test('GET /ready returns 503 before a bundle is loaded and 200 after', async () => {
     app = createWorker({ enableHealthEndpoints: true });