nest-winston: A TypeScript repository from creaux

A Nest module wrapper for winston logger.

Installation

npm install --save nest-winston winston

Quick Start

Import WinstonModule into the root AppModule and use the forRoot() method to configure it. This method accepts the same options object as createLogger() function from the winston package:

import { Module } from '@nestjs/common';
import { WinstonModule } from 'nest-winston';
import * as winston from 'winston';

@Module({
  imports: [
    WinstonModule.forRoot({
      // options
    }),
  ],
})
export class AppModule {}

Afterward, the winston instance will be available to inject across entire project using the winston injection token:

import { Controller, Inject } from '@nestjs/common';
import { WINSTON_MODULE_PROVIDER } from 'nest-winston';
import { Logger } from 'winston';

@Controller('cats')
export class CatsController {
  constructor(@Inject(WINSTON_MODULE_PROVIDER) private readonly logger: Logger) { }
}

Note that WinstonModule is a global module, it will be available in all you feature modules.

Async configuration

Caveats: because the way Nest works, you can't inject dependencies exported from the root module itself (using exports). If you use forRootAsync() and need to inject a service, that service must be either imported using the imports options or exported from a global module.

Maybe you need to asynchronously pass your module options, for example when you need a configuration service. In such case, use the forRootAsync() method, returning an options object from the useFactory method:

import { Module } from '@nestjs/common';
import { WinstonModule } from 'nest-winston';
import * as winston from 'winston';

@Module({
  imports: [
    WinstonModule.forRootAsync({
      useFactory: () => ({
        // options
      }),
      inject: [],
    }),
  ],
})
export class AppModule {}

The factory might be async, can inject dependencies with inject option and import other modules using the imports option.

Alternatively, you can use the useClass syntax:

WinstonModule.forRootAsync({
  useClass: WinstonConfigService,
})

With the above code, Nest will create a new instance of WinstonConfigService and its method createWinstonModuleOptions will be called in order to provide the module options.

Use as the main Nest logger

Apart from application logging, this module also provides the WinstonLogger custom implementation, for use with the Nest logging system. Example main.ts file:

import { WINSTON_MODULE_NEST_PROVIDER } from 'nest-winston';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useLogger(app.get(WINSTON_MODULE_NEST_PROVIDER));
}
bootstrap();

Here the get() method on the NestApplication instance is used to retrieve the singleton instance of WinstonLogger class, which is still configured using either WinstonModule.forRoot or WinstonModule.forRootAsync methods.

When using this technique, you can inject the logger either using the WINSTON_MODULE_PROVIDER token (see the quick start section) or using the WINSTON_MODULE_NEST_PROVIDER token, along with the typing LoggerService from @nestjs/common package:

import { Controller, Inject, LoggerService } from '@nestjs/common';
import { WINSTON_MODULE_NEST_PROVIDER } from 'nest-winston';

@Controller('cats')
export class CatsController {
  constructor(@Inject(WINSTON_MODULE_NEST_PROVIDER) private readonly logger: LoggerService) { }
}

This works because WinstonLogger is an implementation of the LoggerService interface, forwarding all calls to the winston logger (injected) singleton instance.

Use as the main Nest logger (also for bootstrapping)

Using the dependency injection has one minor drawback. Nest has to bootstrap the application first (instantiating modules and providers, injecting dependencies, etc) and during this process the instance of WinstonLogger is not yet available, which means that Nest falls back to the internal logger.

One solution is to create the logger outside of the application lifecycle, using the createLogger function, and pass it to NestFactory.create:

import { WinstonModule } from 'nest-winston';

async function bootstrap() {
  const app = await NestFactory.create(AppModule, {
    logger: WinstonModule.createLogger({
      // options (same as WinstonModule.forRoot() options)
    })
  });
}
bootstrap();

By doing this, you give up the dependency injection, meaning that WinstonModule.forRoot and WinstonModule.forRootAsync are not needed anymore.

To use the logger also in your application, change your main module to provide the Logger service from @nestjs/common:

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

@Module({
    providers: [Logger],
})
export class AppModule {}

Then simply inject the Logger:

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

@Controller('cats')
export class CatsController {
  constructor(@Inject(Logger) private readonly logger: LoggerService) { }
}

This works because Nest Logger wraps our winston logger (the same instance returned by the createLogger method) and will forward all calls to it.

Utilities

The module also provides a custom Nest-like special formatter for console transports:

import { Module } from '@nestjs/common';
import { utilities as nestWinstonModuleUtilities, WinstonModule } from 'nest-winston';
import * as winston from 'winston';

@Module({
  imports: [
    WinstonModule.forRoot({
      transports: [
        new winston.transports.Console({
          format: winston.format.combine(
            winston.format.timestamp(),
            nestWinstonModuleUtilities.format.nestLike(),
          ),
        }),
        // other transports...
      ],
      // other options
    }),
  ],
})
export class AppModule {}

Contributing

New features and bugfixes are always welcome! In order to contribute to this project, follow a few easy steps:

Fork this repository, clone it on your machine and run npm install
Open your local repository with Visual Studio Code and install all the suggested extensions
Create a branch my-awesome-feature and commit to it
Run npm run lint, npm run test and npm run build and verify that they complete without errors
Push my-awesome-feature branch to GitHub and open a pull request