feat: add notification microservices and transactional outbox

apps/notification-service/src/health.controller.ts

@@ -0,0 +1,31 @@
+import { Controller, Get, Inject, ServiceUnavailableException } from '@nestjs/common';
+import { InjectConnection } from '@nestjs/mongoose';
+import { Connection } from 'mongoose';
+import { NOTIFICATION_SERVICE_STATE, NotificationServiceState } from './service-state';
+
+@Controller('health')
+export class HealthController {
+  constructor(
+    @InjectConnection() private readonly connection: Connection,
+    @Inject(NOTIFICATION_SERVICE_STATE) private readonly state: NotificationServiceState,
+  ) {}
+
+  @Get()
+  @Get('live')
+  live() {
+    return { status: this.state.draining ? 'draining' : 'ok', service: 'notification-service' };
+  }
+
+  @Get('ready')
+  async ready() {
+    const mongodbReady = this.connection.readyState === 1;
+    const ready = !this.state.draining && mongodbReady && this.state.rabbitmqReady;
+    const response = {
+      status: ready ? 'ready' : 'not-ready',
+      service: 'notification-service',
+      checks: { mongodb: mongodbReady, rabbitmq: this.state.rabbitmqReady },
+    };
+    if (!ready) throw new ServiceUnavailableException(response);
+    return response;
+  }
+}