Installation

npm install @metinseylan/nestjs-opentelemetry --save

Configuration

This is a basic configuration without any trace and metric exporter, but includes default metrics and injectors

import { OpenTelemetryModule } from '@metinseylan/nestjs-opentelemetry';

@Module({
  imports: [
    OpenTelemetryModule.forRoot({
      serviceName: 'nestjs-opentelemetry-example',
    })
  ]
})
export class AppModule {}

Async configuration example

import { OpenTelemetryModule } from '@metinseylan/nestjs-opentelemetry';
import {ConfigModule, ConfigService} from '@nestjs/config';

@Module({
  imports: [
    OpenTelemetryModule.forRootAsync({
      imports: [ConfigModule],
      useFactory: async (configService: ConfigService) => ({
        serviceName: configService.get('SERVICE_NAME'),
      }),
      inject: [ConfigService]
    })
  ]
})
export class AppModule {}

Default Parameters

OpenTelemetryModule.forRoot() takes OpenTelemetryModuleConfig as a parameter, this type is inherited by NodeSDKConfiguration so you can use same OpenTelemetry SDK parameter.

Distributed Tracing

Simple setup with Zipkin exporter, including with default trace instrumentations.

import { OpenTelemetryModule } from '@metinseylan/nestjs-opentelemetry';
import { ZipkinExporter } from '@opentelemetry/exporter-zipkin';
import { SimpleSpanProcessor } from '@opentelemetry/sdk-trace-base';

@Module({
  imports: [
    OpenTelemetryModule.forRoot({
      spanProcessor: new SimpleSpanProcessor(
        new ZipkinExporter({
          url: 'your-zipkin-url',
        })
      ),
    }),
  ],
})
export class AppModule {}

After setup, your application will be instrumented, so that you can see almost every layer of application in ZipkinUI, including Guards, Pipes, Controllers even global layers like this

List of supported official exporters here.

Trace Decorators

This library supports auto instrumentations for Nestjs layers, but sometimes you need to define custom span for specific method blocks like providers methods. In this case @Span decorator will help you.

import { Injectable } from '@nestjs/common';
import { Span } from '@metinseylan/nestjs-opentelemetry';

@Injectable()
export class AppService {
  @Span()
  getHello(): string {
    return 'Hello World!';
  }
}

Also @Span decorator takes name field as a parameter

@Span('hello')

Trace Providers

In an advanced usage case, you need to access the native OpenTelemetry Trace provider to access them from Nestjs application context.

import { Injectable } from '@nestjs/common';
import { Tracer } from '@opentelemetry/sdk-trace-base';

@Injectable()
export class AppService {
  constructor(private readonly tracer: Tracer) {}

  getHello(): string {
    const span = this.tracer.startSpan('important_section_start');
    // do something important
    span.setAttributes({ userId: 1150 });
    span.end();
    return 'Hello World!';
  }
}

TraceService can access directly current span context and start new span.

import { Injectable } from '@nestjs/common';
import { TraceService } from '@metinseylan/nestjs-opentelemetry';

@Injectable()
export class AppService {
  constructor(private readonly traceService: TraceService) {}

  getHello(): string {
    const span = this.traceService.startSpan('hello');
    // do something
    span.end();
    return 'Hello World!';
  }
}

Auto Trace Instrumentations

The most helpful part of this library is that you already get all of the instrumentations by default if you set up a module without any extra configuration. If you need to avoid some of them, you can use the traceAutoInjectors parameter.

import { Module } from '@nestjs/common';
import {
  OpenTelemetryModule,
  ControllerInjector,
  EventEmitterInjector,
  GuardInjector,
  LoggerInjector,
  PipeInjector,
  ScheduleInjector,
} from '@metinseylan/nestjs-opentelemetry';
import { ZipkinExporter } from '@opentelemetry/exporter-zipkin';
import { SimpleSpanProcessor } from '@opentelemetry/sdk-trace-base';

@Module({
  imports: [
    OpenTelemetryModule.forRoot({
      traceAutoInjectors: [
        ControllerInjector,
        GuardInjector,
        EventEmitterInjector,
        ScheduleInjector,
        PipeInjector,
        LoggerInjector,
      ],
      spanProcessor: new SimpleSpanProcessor(
        new ZipkinExporter({
          url: 'your-zipkin-url',
        }),
      ),
    }),
  ]
})
export class AppModule {}

List of Trace Injectors

Distributed Logging with Trace ID

When you set up your environment with the LoggerInjector class or default configuration, you can see trace id with every log.

Metrics

Simple setup with Prometheus exporter, you need install @opentelemetry/exporter-prometheus

import { OpenTelemetryModule } from '@metinseylan/nestjs-opentelemetry';
import { PrometheusExporter } from '@opentelemetry/exporter-prometheus';

@Module({
  imports: [OpenTelemetryModule.forRoot({
    serviceName: 'nestjs-opentelemetry-example',
    metricReader: new PrometheusExporter({
      endpoint: 'metrics',
      port: 9464,
    })
  })]
})
export class AppModule {}

Now you can access Prometheus exporter with auto collected metrics http://localhost:9464/metrics. Also, you can find different exporters here

Metric Decorators (Deprecated)

If you need to observe simple block of function, you can use some basic decorators like @Counter and @Observer

Counter

import { Injectable } from '@nestjs/common';
import { Counter } from '@metinseylan/nestjs-opentelemetry';

@Injectable()
export class AppService {
  @Counter()
  getHello(): string {
    return 'Hello World!';
  }
}

@Counter decorator is uses OpenTelemetry Counter metric, If you check prometheus exporter you will see metric appservice_gethello_total

@Counter('call_me_mr_fahrenheit', {
  description: 'important function call counting here.'
})

And of course, you can configure your decorator metric, the first parameter is "name" and the second one is MetricOptions

Observer (Deprecated)

import {Injectable} from '@nestjs/common';
import {Observer} from "./Observer";

@Injectable()
export class AppService {
  @Observer('nice_one_observer', {
    description: 'some description here.',
    boundaries: [10, 20, 30],
  })
  getHello(): string {
    return 'Hello World!';
  }
}

@Observer decorator uses OpenTelemetry ValueRecorder metric. If you check Prometheus exporter, you will see metric and configuration parameters same as @Counter.

Metric Providers (Deprecated)

In advanced usage cases, you need to access the native OpenTelemetry Metric provider to access them from the Nestjs application context.

import { Injectable } from '@nestjs/common';
import { Meter } from '@opentelemetry/sdk-metrics-base';
import { Counter } from '@opentelemetry/api-metrics';

@Injectable()
export class AppService {
  private readonly counter: Counter;

  constructor(private readonly meter: Meter) {
    this.counter = this.meter.createCounter('handsome_counter');
  }

  getHello(): string {
    this.counter.add(1);
    return 'Hello World!';
  }
}

Auto Metric Observers (Deprecated)

This library has extendable resource and protocol-specific Auto Observers. All of them come with default module configuration, which you can extend and configure.

import { Module } from '@nestjs/common';
import { PrometheusExporter } from '@opentelemetry/exporter-prometheus';
import {
  ActiveHandlesMetric,
  HttpRequestDurationSeconds,
  OpenTelemetryModule,
} from '@metinseylan/nestjs-opentelemetry';

@Module({
  imports: [
    OpenTelemetryModule.forRoot({
      serviceName: 'nestjs-opentelemetry-example',
      metricAutoObservers: [
        HttpRequestDurationSeconds.build({
          boundaries: [20, 30, 100],
        }),
        ActiveHandlesMetric,
      ],
      metricReader: new PrometheusExporter({
        endpoint: 'metrics',
        port: 9464,
      }),
    }),
  ],
})
export class AppModule {}

.build function takes MetricOptions as a parameter.

List Of Auto Observers (Deprecated)

Example Output for HttpRequestDurationSeconds

Let's Combine All of them

import { Module } from '@nestjs/common';
import { PrometheusExporter } from '@opentelemetry/exporter-prometheus';
import { OpenTelemetryModule } from '@metinseylan/nestjs-opentelemetry';
import { ZipkinExporter } from '@opentelemetry/exporter-zipkin';
import { SimpleSpanProcessor } from '@opentelemetry/sdk-trace-base';

@Module({
  imports: [
    OpenTelemetryModule.forRoot({
      serviceName: 'nestjs-opentelemetry-example',
      metricReader: new PrometheusExporter({
        endpoint: 'metrics',
        port: 9464,
      }),
      spanProcessor: new SimpleSpanProcessor(
        new ZipkinExporter({
          url: 'your-zipkin-url',
        })
      ),
    }),
  ],
})
export class AppModule {}