Logger

NestJS Logger for Catalist Finance projects. Part of Catalist NestJS Modules

The logger is based on winston logger and nest-winston package.

Install

yarn add @catalist-nestjs/logger

Usage

Basic usage

import { Module } from '@nestjs/common';
import { LoggerModule, jsonTransport } from '@catalist-nestjs/logger';

@Module({
  imports: [
    LoggerModule.forRoot({
      level: 'debug',
      transports: [jsonTransport()],
    }),
  ],
})
export class AppModule {}

Async usage

import { Module } from '@nestjs/common';
import { LoggerModule, jsonTransport } from '@catalist-nestjs/logger';
import { ConfigModule, ConfigService } from './example';

@Module({
  imports: [
    LoggerModule.forRootAsync({
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: async (configService: ConfigService) => ({
        level: configService.get('LOG_LEVEL'),
        transports: [jsonTransport()],
      }),
    }),
  ],
})
export class AppModule {}

Transports

The logger provides preconfigured console transports in json and simple formats. The transports can be imported from @catalist-nestjs/logger:

import { simpleTransport, jsonTransport } from '@catalist-nestjs/logger';

Secrets cleaner

Preconfigured transports have formatter for clean secrets from logs. To use it, pass an array of secret strings to the transport options:

import { Module } from '@nestjs/common';
import { LoggerModule, simpleTransport } from '@catalist-nestjs/logger';

const PRIVATE_KEY = '0x000000000000';
const secrets = [PRIVATE_KEY];

@Module({
  imports: [
    LoggerModule.forRoot({
      level: 'debug',
      transports: [simpleTransport({ secrets })],
    }),
  ],
})
export class AppModule {}

Secrets will be replaced with text <removed>.

If you want to use this formatter in your custom transport, import the cleanSecrets from @catalist-nestjs/logger:

import { cleanSecrets } from '@catalist-nestjs/logger';

const myFormatter = winston.format.combine(
  cleanSecrets({ secrets: ['some-secret'] }),
  winston.format.json(),
);

const myTransport = new winston.transports.Console({
  format: myFormatter,
});

Meta fields

Meta fields can be useful for adding additional fields to logs, such as blockNumber in Ethereum bots. To add meta fields, pass a defaultMeta to logger options:

import { Module } from '@nestjs/common';
import { LoggerModule, jsonTransport } from '@catalist-nestjs/logger';

@Module({
  imports: [
    LoggerModule.forRoot({
      level: 'debug',
      defaultMeta: {
        foo: 'bar',
        get baz() {
          // you can use getter for dynamic data
          return 1 + 1;
        },
      },
      transports: [jsonTransport()],
    }),
  ],
})
export class AppModule {}

In this case you will see extra fields in the logs:

logger.log('some message'); // { foo: 'bar', baz: 2, message: 'some message', ... }

Colorize

For simple transport you can set colors for meta fields by passing fieldColors in the transport options:

import { Module } from '@nestjs/common';
import { LoggerModule, simpleTransport } from '@catalist-nestjs/logger';

const fieldColors = { foo: 'blue' };

@Module({
  imports: [
    LoggerModule.forRoot({
      level: 'debug',
      defaultMeta: {
        get block() {
          return 1000;
        },
      },
      transports: [simpleTransport({ fieldColors })],
    }),
  ],
})
export class AppModule {}

In this case you will see blue value of block field in the logs:

logger.log('some message'); // yyyy-mm-dd hh:mm:ss [1000] info: some message

Possible color values can be found in the winston docs.