OnApplicationShutdown

Kind: Interface

Source: packages/common/interfaces/hooks/on-application-shutdown.interface.ts

Part of: Common

Interface defining method to respond to system signals (when application gets shutdown by, e.g., SIGTERM)

OnApplicationShutdown is a lifecycle hook interface for providers that need to perform cleanup when the application is shutting down. Implement onApplicationShutdown() to respond to operating-system signals such as SIGTERM and release resources such as database connections, queues, or background workers.

Diagram

mermaid
graph LR
  Signal[OS signal: SIGTERM / SIGINT] --> App[Nest application]
  App --> Lifecycle[Shutdown lifecycle hooks]
  Lifecycle --> Hook[OnApplicationShutdown]
  Hook --> Cleanup[Release resources and cleanup]

Usage

ts
import { Injectable, OnApplicationShutdown } from '@nestjs/common';

@Injectable()
export class DatabaseService implements OnApplicationShutdown {
  async onApplicationShutdown(signal?: string) {
    console.log(`Application shutting down via ${signal ?? 'unknown signal'}`);

    // Close database connections, stop workers, flush telemetry, etc.
    await this.closeDatabaseConnection();
  }

  private async closeDatabaseConnection() {
    // Cleanup implementation
  }
}

// Enable shutdown hooks during application bootstrap:
// const app = await NestFactory.create(AppModule);
// app.enableShutdownHooks();

AI Coding Instructions

• Implement onApplicationShutdown(signal?: string) in injectable providers that own resources requiring graceful cleanup.
• Enable shutdown hooks with app.enableShutdownHooks(); the hook is not invoked for OS signals unless shutdown hooks are enabled.
• Treat the optional signal parameter as informational, since shutdown can also be initiated programmatically.
• Make cleanup operations idempotent and safe to run during partial application initialization.
• Await asynchronous cleanup work so connections, queues, and telemetry are properly flushed before process exit.

Used by

3 references from 3 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (3)

• ServerGateway — integration/websockets/src/server.gateway.ts:6
• ClientsModule — packages/microservices/module/clients.module.ts:17
• callAppShutdownHook — packages/core/hooks/on-app-shutdown.hook.ts:45