Introduction

@infineit/winston-logger is a lightweight project for implements a production-ready logger for Nest.js applications using Winston, Morgan and Prisma. This package simplifies the setup of logger and provides configurable options for instrumenting your application.

Features

• Easy Integration: Quickly integrate logger with winston for distributed log.
• Configurable: Provides options to customize logger configuration.
• Lightweight: Minimal dependencies and overhead.

That implements a production-ready system advanced or basic Microservices or Monoliths projects applying concepts like:

• Correlation IDs
• Decoupled log transporters
• Log levels
• Logging Rules
• Log formatters

Installation

• You can install this package using npm:

  npm install @infineit/winston-logger

  Or using Yarn:

  yarn add @infineit/winston-logger

Prerequisites

• NestJS
• Winston
• morgon
• prisma

Getting Started

Follow these steps to set up and run logger. If all steps are followed correctly, logger should start without any issues:

1. To use @infineit/winston-logger in your NestJS application, simply import it of your main.ts file:

       import { NestjsLoggerServiceAdapter } from '@infineit/winston-logger';;
   
       const app = await NestFactory.create(AppModule, {bufferLogs: true });
   
       app.useLogger(app.get(NestjsLoggerServiceAdapter));

2. import in app.module.ts:

     import { ContextModule, LoggerModule } from '@infineit/winston-logger';
   
     @Module({
       imports: [
         ContextModule,
         LoggerModule.forRoot(PrismaService),
       ]
     })

3. app.service.ts:

     import Logger, { LoggerKey } from '@infineit/winston-logger';
   
     constructor(@Inject(LoggerKey) private logger: Logger) {}
   
     this.logger.info('I am an info message!', {
           props: {
               foo: 'bar',
               baz: 'qux',
           },
       });

Reminder: Make sure prisma is initialize and winstonlog modal is running before starting your NestJS application to avoid initialization errors.

Configuration

You can configure the Logger using environment variables in your .env file:

• NODE_ENV: development / staging / testing / production.
• LOGGER_ORGANIZATION: The name of your organization as it will appear in log.
• LOGGER_CONTEXT: The name of your context as it will appear in log.
• LOGGER_APP: The name of your app as it will appear in log.
• LOGGER_DATABASE_STORAGE: True/False. Default True for production or testing, It will store log to database.
• LOGGER_LOG_LEVEL: Default log level warn,error,fatal for production or testing, It will log.
• LOGGER_DURATION: True/False. Default False, It will store request duration in database.
• LOGGER_DURATION_LOG_LEVEL: Default log level warn,error,fatal for production or testing, It will calculate duration for request.
• LOGGER_CONSOLE_PRINT: True/False. Default False for production or testing.
• LOGGER_LOG_IN_FILE: True/False. Default False for production or testing.
• LOGGER_SLACK_INC_WEBHOOK_URL: Slack url, eg. https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXXX.

Project structure

Key concepts

NestJS Logger

NestJS uses a custom logger for bootstrap and internal logging. To use our logger, we need to create an adapter that implements the NestJS LoggerService interface. That is implemented in the NestjsLoggerServiceAdapter class.

We pass that adapter to the NestJS app on the main.ts file.

Correlation IDs

To manage correlation IDs, we use nestjs-cls library that implements a Local Storage. With that, we can isolate and share data on a request lifecycle.

The system reads the x-correlation-id HTTP header and stores it on the Local Storage. If the header is not present, the system generates a new UUID and stores it on the Local Storage.

Context Wrapper

To add custom data to all the logs, we use a wrapper LoggerContextWrapper.

That class is injected with a Transient scope. By that, we can get the caller class and add it to the logs.

Prisma Table

    model winstonlog {
        id_log        String   @id @default(dbgenerated("gen_random_uuid()")) @db.Uuid
        level         String   @db.VarChar(80)
        message       String   @db.Text
        context       String?  @db.VarChar(255)
        correlationId String?  @db.Uuid
        sourceClass   String?  @db.VarChar(255)
        props         Json?
        organization  String?  @db.VarChar(40)
        app           String?  @db.VarChar(40)
        durationMs    Decimal? @default(0) @db.Decimal(10, 4)
        stack         String?  @db.Text
        label         String?  @db.VarChar(40)
        timestamp     DateTime @default(now()) @db.Timestamptz(6)

        @@schema("public")
    }

Inspiration

This project is inspired by the excellent work from:

• Medium
• Logger
• winston-pg

License

This project is licensed under the MIT License. See the LICENSE file for more details.

Author

Dharmesh Patel 🇮🇳

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