Description
A logger module for Nestjs, built on top of node-bunyan.
Features
- A gloabl bunyan logger provider can be used in the controllers/services.
- Automatically log request/response with
request-id
, timestamp
, status-code
, etc.
Usage
Installation
Yarn
yarn add @wiredcraft/nestjs-bunyan-logger
NPM
npm install @wiredcraft/nestjs-bunyan-logger --save
Integration
- Import
LoggerModule
in the root App module, this provides initialized bunyan logger instance that is available to other modules by injection.
import { Module } from '@nestjs/common';
import { LoggerConfig, LoggerModule } from '@wiredcraft/nestjs-bunyan-logger';
import configuration from './src/configuration';
@Module({
imports: [
ConfigModule.forRoot({
load: [configuration],
}),
LoggerModule.forRootAsync({
imports: [ConfigModule],
useFactory: async (configService: ConfigService) => {
return configService.get<LoggerConfig>('logger', { infer: true });
},
inject: [ConfigService],
}),
],
})
export class AppModule {}
A sample configuration file is as below,
export default () => ({
logger: {
name: 'awesome-app',
streamType: 'FILE' | 'STDOUT',
path: './logs/app.log',
excludeReqPath: '/health',
},
});
- Inject the logger instance to your service and use it as you want.
import { Injectable } from '@nestjs/common';
import { Logger, Bunyan } from '@wiredcraf/nestjs-bunyan-logger';
@Injectable()
export class CatService {
constructor(@Logger() private logger: Bunyan) {}
}
Transformers Option
transformers
is a config option that could allow the user to specify a list of customized transform rules to apply to each log entry. The current library supports three types of transformers: constant
, clone
and map
.
Constant
constant
type allows the user to copy a object type constant directly to the log entry. An example is as follows:
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers: [{ constant: { customField: '123' } }],
};
logger.info({ originalField: 'abc' });
Clone
clone
type allows the user to copy value from one fieldname to the specified fieldname with the following rules:
- The original field is not removed from the log entry
- Only one embed level is allowed in new Fieldname specification
An example is as follows:
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers: [{ clone: { originalField: 'newField' } }],
};
logger.info({ originalField: 'abc' });
An one embed level example is as follows:
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers: [{ clone: { originalField: 'newParent.newField' } }],
};
logger.info({ originalField: 'abc' });
Map
map
type allows the user to apply a map value or a map function to the target field and replace the field value with the mapped value with the following rules:
- only one embed level is allowed for original field name specification
An example of simple map value is as follows:
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers: [{ map: { originalField: 'new-value' } }],
};
logger.info({ originalField: 'abc' });
An example of map function is as follows:
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers: [
{ map: { originalField: (oldValue) => oldValue + 'transformed' } },
],
};
logger.info({ originalField: 'abc' });
An one embed level example is as follows:
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers: [
{ map: { ['originalParentField.originalField']: 'new-value' } },
],
};
logger.info({
originalParentField: {
originalField: 'abc',
},
});
Multiple transformers
Multiple transformers are applied in the order as they are specified in the transformers
option. An example is as follows:
const transformers = [
{
constant: { customField: 'custom-value' },
},
{
clone: { originalField: 'backupField' },
},
{
map: { originalField: (oldValue) => oldValue + 'transformed' },
},
];
const options: LoggerConfig = {
name: 'test-app',
streamType: 'STDOUT',
transformers,
};
logger.info({ originalField: 'original-value' });
Development
Installation
$ npm install
Publish
$ npm version major|minor|patch
$ npm publish
License
MIT licensed.