Health checks

The /health endpoint is provided by @nestjs/terminus through HealthModule. It returns a single JSON object with the status of every registered indicator.

Default checks

The generated HealthController registers four checks:

• github — HTTP ping to https://github.com to verify outbound connectivity.
• disk health — Disk usage at / with a 75% threshold.
• memory heap — Heap usage with a 150 MB threshold.
• memory RSS — RSS usage with a 150 MB threshold.

src/monitoring/health/health.controller.ts

@Get()
@HealthCheck()
check() {
  return this.health.check([
    () => this.http.pingCheck('github', 'https://github.com'),
    () => this.disk.checkStorage('disk health', { thresholdPercent: 0.75, path: '/' }),
    () => this.memory.checkHeap('memory heap', 150 * 1024 * 1024),
    () => this.memory.checkRSS('memory RSS', 150 * 1024 * 1024),
  ]);
}

Adding a check

Add a function that returns a HealthIndicatorResult. For example, to check Redis:

import { RedisService } from 'nestjs-redis-client';

@Controller('health')
export class HealthController {
  constructor(
    private health: HealthCheckService,
    private http: HttpHealthIndicator,
    private disk: DiskHealthIndicator,
    private memory: MemoryHealthIndicator,
    private redis: RedisService,
  ) {}

  @Get()
  @HealthCheck()
  check() {
    return this.health.check([
      () => this.http.pingCheck('github', 'https://github.com'),
      () => this.disk.checkStorage('disk health', { thresholdPercent: 0.75, path: '/' }),
      () => this.memory.checkHeap('memory heap', 150 * 1024 * 1024),
      () => this.memory.checkRSS('memory RSS', 150 * 1024 * 1024),
      () => this.checkRedis(),
    ]);
  }

  private async checkRedis() {
    await this.redis.getClient().ping();
    return { redis: { status: 'up' } };
  }
}

Health response format

A healthy response returns HTTP 200:

{
  "status": "ok",
  "info": { "github": { "status": "up" }, ... },
  "error": {},
  "details": { "github": { "status": "up" }, ... }
}

If any check fails, the endpoint returns HTTP 503 and the failing indicator is listed under error and details.

Load balancers and orchestrators

Use the /health endpoint for Kubernetes liveness/readiness probes or load balancer health checks. Keep the checks lightweight: expensive checks will delay the response and can cause unnecessary restarts.