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

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

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