typescript 36 lines · 7 steps

Graceful shutdown hooks in NestJS

A service that cleanly drains Redis, TypeORM, and Kafka connections when the app receives a shutdown signal.

Explained by highlit
NestJS Intermediate graceful-shutdown lifecycle-hooks dependency-injection promise-handling resource-cleanup
1import { Injectable, Logger, OnApplicationShutdown } from '@nestjs/common';
2import { InjectRedis } from '@nestjs-modules/ioredis';
3import Redis from 'ioredis';
4import { DataSource } from 'typeorm';
5import { KafkaProducer } from './kafka.producer';
6 
7@Injectable()
8export class ConnectionLifecycleService implements OnApplicationShutdown {
9 private readonly logger = new Logger(ConnectionLifecycleService.name);
10 
11 constructor(
12 @InjectRedis() private readonly redis: Redis,
13 private readonly dataSource: DataSource,
14 private readonly producer: KafkaProducer,
15 ) {}
16 
17 async onApplicationShutdown(signal?: string): Promise<void> {
18 this.logger.log(`Received ${signal ?? 'shutdown'} signal, draining connections`);
19 
20 const results = await Promise.allSettled([
21 this.producer.flush(5_000).then(() => this.producer.disconnect()),
22 this.redis.quit(),
23 this.dataSource.isInitialized
24 ? this.dataSource.destroy()
25 : Promise.resolve(),
26 ]);
27 
28 for (const result of results) {
29 if (result.status === 'rejected') {
30 this.logger.error('Failed to close a resource cleanly', result.reason);
31 }
32 }
33 
34 this.logger.log('All external resources released');
35 }
36}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Implementing OnApplicationShutdown lets NestJS notify your service when the process is terminating, giving you a hook to release resources.
  2. 2Promise.allSettled runs all cleanup in parallel and never short-circuits, so one failing resource doesn't abandon the others.
  3. 3Flushing buffered work before disconnecting prevents in-flight messages from being silently dropped on exit.

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