Logging and Monitoring Strategies for NestJS

Logging and monitoring are essential for understanding the behavior of your application, diagnosing issues, and ensuring its health and performance. We'll explore how to implement logging and monitoring in your NestJS application using built-in features and third-party tools. NestJS provides a built-in logger service that you can use to log messages at different levels of severity, such as log, error, warn, and debug. You can configure the logger to write messages to different destinations, such as the console, files, or external services. Here's an example of how to use the logger service in a controller:

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

@Controller('cats')
export class CatsController {
  private readonly logger = new Logger(CatsController.name);
  @Get()
  findAll() {
    this.logger.log('Finding all cats...');
    return [];
  }
}        

Monitoring with Prometheus and Grafana

Prometheus is a popular open-source monitoring and alerting toolkit, while Grafana is a visualization tool that can be used with Prometheus to create dashboards and graphs. You can use these tools to monitor various metrics of your NestJS application, such as HTTP request latency, error rates, and memory usage. Here's an example of how to configure Prometheus and Grafana in a NestJS application:

1. Install the necessary packages:

npm install --save @nestjs/metrics prom-client        

2. Configure Prometheus in your main.ts file:

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { PrometheusInterceptor } from '@nestjs/metrics';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  // Enable metrics
  app.usePrometheus();

  // Add Prometheus metrics interceptor
  app.useGlobalInterceptors(new PrometheusInterceptor());
  await app.listen(3000);
}

bootstrap();
        

3. Configure Grafana to visualize the metrics collected by Prometheus.

Logging and monitoring are essential for understanding and maintaining the health and performance of your NestJS application. By implementing logging with NestJS's built-in logger service and monitoring with tools like Prometheus and Grafana, you can gain valuable insights into your application's behavior and performance.