open-logger-facade v0.0.17

open-logger-facade

A simple logger facade for NodeJS, an abstraction class for logging. Works and tested with winston and pino. If you're working with TypeScript, you might want to use @Logger decorator (require reflect-metadata).

Installation

npm install -S open-logger-facade

Usage

# in your index file
import { LoggerContext, LoggerFactory } from "open-logger-facade";
import * as pino from "pino";

LoggerContext.use(pino());
const logger = LoggerFactory.getLogger();
logger.fatal(`fatal message`);
logger.error(`error message`);
logger.warn(`warn message`);
logger.info(`info message`);
logger.debug(`debug message`);
logger.trace(`trace message`);
...

# in other files, you just need to call LoggerFactory.getLogger() to get the logger instance, ie.
## Other.js
class OtherClass {
    doSomething() {
        const logger = LoggerFactory.getLogger();
        logger.debug(`debug message`);
    }
}
// This is useful when you have Service or Repository classes, you can get logger instance without passing it around as parameter

open-logger-facade is just an simple interface to bridge between your code and logger library, the idea is to decoupled code with logger implementation. This way your project is loosely coupled with any logger library, and you can switch between logger libraries very easily (given the logger implementation is using the same leveled method fatal, error, warn, info, debug, and trace).

In case you're using winston, it is recommended you're changing the levels to match above levels. This way, you can switch with other loggers such as pino or bunyan without refactoring your codes too much. See examples/WinstonExample.js and examples/WinstonExampleTS.ts if you're using TypeScript.

pino and bunyan also had those levels, so they should works out of the box with open-logger-facade.

Configuring winston

import * as winston from "winston";
import { LoggerContext, LoggerFactory } from "open-logger-facade";

const winstonLogger = winston.createLogger({
        level: "trace",
        exitOnError: false,
        transports: [new winston.transports.Console()],
        levels: {
            fatal: 0,
            error: 1,
            warn: 2,
            info: 3,
            debug: 4,
            trace: 5
        }
    });

LoggerContext.use(winstonLogger);
const logger = LoggerFactory.getLogger();

logger.trace(`Hello World!`);

@Logger decorator

• Install reflect-metadata

npm install -S reflect-metadata

• Enable experimentalDecorators and emitDecoratorMetadata inside your tsconfig.json

"experimentalDecorators": true,
"emitDecoratorMetadata": true,

• In your root file (index.ts), import reflect-metadata

Example

MyClass.ts

import { Logger } from "open-logger-facade/decorators/Logger";
class MyClass {
    @Logger()
    logger!: ILogger;

    someFunc() {
        this.logger.info(`Hello from MyClass!`);
    }
}

index.ts

import "reflect-metadata";
import { LoggerContext, LoggerFactory } from "open-logger-facade";
import * as pino from "pino";
import {MyClass} from "./MyClass"
...
LoggerContext.use(pino());


const myClass = new MyClass();
myClass.someFunc();