Health checks (Terminus) in NestJS - Mini Project: Build & Apply

Health Checks with Terminus in NestJS

📖 Scenario: You are building a simple NestJS server that needs to report its health status. This is important for monitoring and ensuring the server is running well.

🎯 Goal: Create a health check endpoint using Terminus in NestJS that reports the server is healthy.

📋 What You'll Learn

Create a health check controller

Configure Terminus health check module

Implement a basic health check returning 'ok' status

Expose the health check endpoint at '/health'

💡 Why This Matters

🌍 Real World

Health checks help monitor if your server and its dependencies are working well. This is important for uptime and reliability.

💼 Career

Many companies use health checks in their backend services to integrate with monitoring tools and orchestrators like Kubernetes.

1

Setup Health Check Controller

Create a controller called HealthController with a route /health that will later return health status.

NestJS

import { Controller, Get } from '@nestjs/common';

@Controller('health')
export class HealthController {
  // Your code here
}

Need a hint?

Use @Controller('health') to set the route and @Get() for the GET method.

2

Add Terminus Health Module

Import TerminusModule from @nestjs/terminus and add it to the imports array of your main application module called AppModule.

NestJS

import { Controller, Get } from '@nestjs/common';

@Controller('health')
export class HealthController {
  @Get()
  check() {
    return { status: 'ok' };
  }
}

import { Module } from '@nestjs/common';
import { TerminusModule } from '@nestjs/terminus';

@Module({
  controllers: [HealthController],
  imports: [
    // Your code here
  ],
})
export class AppModule {}

Need a hint?

Remember to import TerminusModule and add it to the imports array in @Module.

3

Use Terminus Health Check Service

Inject HealthCheckService and HttpHealthIndicator into HealthController. Use HealthCheckService.check() with HttpHealthIndicator.pingCheck('nestjs-docs', 'https://docs.nestjs.com') inside the check() method to perform a real health check.

NestJS

import { Controller, Get } from '@nestjs/common';
import { HealthCheckService, HttpHealthIndicator, HealthCheck } from '@nestjs/terminus';

@Controller('health')
export class HealthController {
  constructor(
    private health: HealthCheckService,
    private http: HttpHealthIndicator,
  ) {}

  @Get()
  @HealthCheck()
  check() {
    // Your code here
  }
}

import { Module } from '@nestjs/common';
import { TerminusModule } from '@nestjs/terminus';

@Module({
  controllers: [HealthController],
  imports: [TerminusModule],
})
export class AppModule {}

Need a hint?

Use dependency injection in the constructor and call this.health.check() with this.http.pingCheck() inside the check() method.

4

Complete and Test Health Endpoint

Ensure the HealthController and AppModule are correctly set up with Terminus. The health check endpoint should be accessible at /health and return JSON with the status of the ping check.

NestJS

import { Controller, Get } from '@nestjs/common';
import { HealthCheckService, HttpHealthIndicator, HealthCheck } from '@nestjs/terminus';

@Controller('health')
export class HealthController {
  constructor(
    private health: HealthCheckService,
    private http: HttpHealthIndicator,
  ) {}

  @Get()
  @HealthCheck()
  check() {
    return this.health.check([
      () => this.http.pingCheck('nestjs-docs', 'https://docs.nestjs.com'),
    ]);
  }
}

import { Module } from '@nestjs/common';
import { TerminusModule } from '@nestjs/terminus';

@Module({
  controllers: [HealthController],
  imports: [TerminusModule],
})
export class AppModule {}

// Confirm the setup is complete and ready for testing

Need a hint?

Review all previous steps and ensure the health check endpoint is fully implemented and the module imports are correct.