typescript 45 lines · 8 steps

A per-route timeout interceptor in NestJS

A NestJS interceptor that aborts slow requests using a metadata-driven, per-handler timeout and returns a clean HTTP error.

Explained by highlit
NestJS Intermediate interceptors metadata reflection rxjs timeouts error handling
1import {
2 Injectable,
3 NestInterceptor,
4 ExecutionContext,
5 CallHandler,
6 RequestTimeoutException,
7 Logger,
8} from '@nestjs/common';
9import { Reflector } from '@nestjs/core';
10import { Observable, throwError, TimeoutError } from 'rxjs';
11import { catchError, timeout } from 'rxjs/operators';
12 
13export const REQUEST_TIMEOUT_KEY = 'request_timeout_ms';
14 
15@Injectable()
16export class TimeoutInterceptor implements NestInterceptor {
17 private readonly logger = new Logger(TimeoutInterceptor.name);
18 private readonly defaultTimeout = 5000;
19 
20 constructor(private readonly reflector: Reflector) {}
21 
22 intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
23 const timeoutMs =
24 this.reflector.getAllAndOverride<number>(REQUEST_TIMEOUT_KEY, [
25 context.getHandler(),
26 context.getClass(),
27 ]) ?? this.defaultTimeout;
28 
29 return next.handle().pipe(
30 timeout(timeoutMs),
31 catchError((err) => {
32 if (err instanceof TimeoutError) {
33 const request = context.switchToHttp().getRequest();
34 this.logger.warn(
35 `${request.method} ${request.url} exceeded ${timeoutMs}ms`,
36 );
37 return throwError(
38 () => new RequestTimeoutException('Request processing timed out'),
39 );
40 }
41 return throwError(() => err);
42 }),
43 );
44 }
45}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Interceptors can wrap the response stream to enforce cross-cutting concerns like timeouts without touching handler code.
  2. 2Reflector.getAllAndOverride lets a route-level decorator override a class-level or default value cleanly.
  3. 3Translating an RxJS TimeoutError into a domain exception keeps clients from leaking internal error shapes.

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