nestjs-logging-utils

Why and what?

This package alters the default logging behaviour for NestJS when using the winston logger integration. YMMV if you like this more. To make use of any features you need to use the Logger class from this package. Besides the error() method this should be compatible with the logger shipped by NestJS.

Changes made to default logging:

Context

By default the NestJS logger takes a string parameter called context. This package considers this the logger's name. It also can't be overriden by providing the context to one of the logger's methods.

logger.*()

Originally the context for log methods should be a string. Due to loose typing this can however be anything. This package provides support for context objects.

logger.error()

The error() method "gains" two new signatures.

class Logger {
  /* ... */
  error(message: string, error: Error, context?: Record<string, unknown>): void;
  error(error: Error, context?: Record<string, unknown>): void;
  /* ... */
}

If you use these your exception aren't unpacked any longer and will no longer accidentially leak confidental data into your logs. If you need information from exception you can add an error handler to the logger. Like this

Logger.errorContextHandlers.push((error) => {
  if (axios.isAxiosError(error)) {
    const httpError = {
      code: error.code,
      message: error.message,
      response: {
        status: error.response?.status,
        data: error.response?.data,
      },
      config: {
        url: error.config?.url,
        method: error.config?.method,
      },
    };
    return httpError;
  }
  return null;
});

This would add additional context for all axios-related errors.

Install

npm install @boringplanet/nestjs-logging-utils

Usage

Put this in a file in your NestJS project

import { nestLikeLogger } from '@boringplanet/nestjs-logging-utils';
import { WinstonModule } from 'nest-winston';
import * as winston from 'winston';

export const transports: winston.transport[] = [
  new winston.transports.Console({
    level: 'debug',
    format: winston.format.combine(
      winston.format.timestamp(),
      nestLikeLogger({ projectName: 'your-cool-project', colors: true }),
    ),
  }),
];

export const logger = WinstonModule.createLogger({
  transports,
});

to use the winston logger change your main.ts like this

const app = await NestFactory.create(AppModule, { logger });

This will mimic NestJS's default logging output. Context objects are safe-stringified and appended to the logs. There is also some support for themes. You can pass a theme to the nestLikeLogger method or set on via environment. Currently this package only ships a gruvbox theme.

NESTJS_LOGGER_THEME=gruvbox

# Other env vars
NESTJS_LOGGER_LOG_PID="true"
NESTJS_LOGGER_LOG_PROJECT_NAME="true"