NestJS Datadog Trace

dd-trace 5.x
nest 10.3

Install

``sh
npm i @nestpro/dd-trace
`

Setup

1. Create tracing file (tracing.ts):

`ts
import DataDogTrace from 'dd-trace';

const tracer = DataDogTrace.init({
logInjection: true,
});

export { tracer };
`

Use already initialized DataDog tracer instance


2. Import the tracing file:

`ts
import './tracing';
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { Logger as PinoLogger } from 'nestjs-pino';
import { Logger } from '@nestjs/common';

async function bootstrap() {
const app = await NestFactory.create(AppModule, { bufferLogs: true });
app.useLogger(app.get(PinoLogger));

const logger = new Logger('main');
const port = process.env.PORT || 3000;
await app.listen(3000).then(() => {
logger.log(Listening on port: ${port});
});
}
bootstrap();
`

Use APP_ prefix for your application configuration environment variables.


3. Add LoggerModule and DatadogModule to AppModule:

`ts
import { Module } from '@nestjs/common';
import { LoggerModule } from 'nestjs-pino';
import { DatadogTraceModule } from 'nestjs-ddtrace';

@Module({
imports: [
LoggerModule.forRoot({
pinoHttp: {
level: process.env.APP_ENV !== 'prod' ? 'trace' : 'info'
},
exclude: [{ method: RequestMethod.ALL, path: 'health' }], // if you have /health path, exclude it from logs
}),
DatadogTraceModule.forRoot({
controllers: true,
providers: true
})
],
})
export class AppModule {}
`

Span Decorator

If you need, you can define a custom Tracing Span for a method or class. It works async or sync. Span takes its name from the parameter; but by default, it is the same as the method's name.

`ts
import { DatadogTraceModule } from 'nestjs-ddtrace';

@Module({
imports: [DatadogTraceModule.forRoot()],
})

export class AppModule {}
`

$3

In case you need to access native span methods for special logics in the method block:

`ts
import { Span, TraceService } from 'nestjs-ddtrace';

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

@Span()
async getBooks() {
const currentSpan = this.traceService.getActiveSpan(); // --> retrives current span, comes from http or @Span
await this.doSomething();
currentSpan.addTags({
'getBooks': 'true'
});

const childSpan = this.traceService.getTracer().startSpan('ms', {childOf: currentSpan});
childSpan.setTag('userId', 1);
await this.doSomethingElse();
childSpan.finish(); // new span ends

try {
doSomething();
} catch (e) {
currentSpan.setTag('error', e);
throw e;
}
return [Harry Potter and the Philosopher's Stone];
}
}
`

`ts
import { Span } from 'nestjs-ddtrace';

@Injectable()
@Span()
export class BookService {
async getBooks() { / ... / }
async deleteBook(id: string) { / ... / }
}

@Controller()
@Span()
export class HelloController {
@Get('/books')
getBooks() { / ... / }

@Delete('/books/:id')
deleteBooks() { / ... / }
}
``

Miscellaneous

Inspired by the nestjs-otel and nestjs-opentelemetry repository.