Feel Logger

This is my default configuration for winston logger.

Table of contents

• Motivation
• Quick Start
• Outpu Format
• Configuration
• Dynamic Initialization
• Logger Interface
• Loggin Context
• Logger Instance
• Wisnton Instance

Motivation

Winston is an incredible and versatile logging library. To simplify the configuration process and keep the logs consistent across projects, i decided to create this package to easily setup winston with my formats and configurations.

This package has two default transports: Console and Dayle Rotate File.

Quick Start

You just need to import Logger and call the init method and a Console logger will be created.

import { Logger } from 'feel-logger';

Logger.init();
Logger.info('My Awesome Logger!');
// output: 2020-07-12 13:43:05 [Application] INFO: My Awesome Logger!

To activate the Daily Rotate File just pass a configuration object to init method.

import { Logger } from 'feel-logger';

Logger.init({ file: true });
Logger.info('My Awesome Logger!');

This will create a /logs folder in the project root and store there the logs files.

Output Format

The output format is composed by a timestamp, a identifier label, the log level, the log message and the associated metadata.

 YYYY-MM-DD HH:MM:SS [label] LEVEL: message Meta: ...

Configuration

The configurations accepted by the Logger are:

| property | type | default | description | | --------------- | --------------------------------- | ------------------------------ | ----------------------------------------- | | name | string | Application | this will be the label | | level | string | info | the log level | | exitOnError | boolean | false | | | handleException | boolean | false | | | transports | Winston.Transports[] | Console, Daily Rotate File | custom transports to be add to the Logger | | file | boolean | false | active Dayle Rotate File transport | | fileOptions | DailyRotateFileTransportOptions | null | overrides default transport options | | console | WinstonLoggerOptions | null | overrides default transport options |

Dynamic Initialization

To make the Logger instance static across the application you have to create a logger.options file. When the lib is loaded by node it will be search for a configuration file (.js or .ts) in the project. This dynamic initialization overrides init method.

    +-- root
    |   +-- src
    |   |   +-- configuration.options.[ts|js]
    |   +-- package.json

The configuration file accepts the same object as the init method, but make sure that your logger.options.[ts|js] is inside a src folder under the root directory and follow the conventions:

/* logger.options.js */
module.exports = {
    file: true,
};

/* logger.options.ts */
export default {
    file: true,
};

Now you can import Logger in any file and use without pass through injection.

/* AccountController */
import { Logger } from 'feel-logger';

export class AwesomeClass {
    AwesomeMethod() {
        Logger.info('Awesome Method Called');
    }
}

Logger Interface

The following is the methods for logging:

interface LoggerOperations {
    log: (level: string, message: string) => void;
    info: (message: string, ...meta: unknown[]) => void;
    warning: (message: string, ...meta: unknown[]) => void;
    error: (message: string, ...meta: unknown[]) => void;
    debug: (message: string, ...meta: unknown[]) => void;
}

Logging Context

If you want to add a context information to the output log you can pass a special metadata called context and it will be add to the label part of the log.

import { Logger } from 'feel-logger';

Logger.info('My Awesome Logger', { context: 'MyContext' });
// output: 2020-07-12 14:42:29 [Application - MyContext] INFO: My Awesome Logger

Logger Instance

If you initialize your Logger dynamically, you can create instances of the logger to set a default context.

import { Logger } from 'feel-logger';

const logger = Logger.createLoggerInstance('MyDefaultContext');
logger.info('My Awesome Logger');
// output: 2020-07-12 14:47:31 [Application - MyDefaultContext] INFO: My Awesome Logger

You can pass a class type as well.

import { Logger } from 'feel-logger';

export class MyAwesomeClass {
    logger = Logger.createLoggerInstance(MyAwesomeClass);

    log() {
        this.logger.info('My Awesome Logger');
    }
}

new MyAwesomeClass().log();
// output: 2020-07-12 14:47:31 [Application - MyAwesomeClass] INFO: My Awesome Logger

Winston Instance

You can get the winston instance object by calling the method:

import { Logger } from 'feel-logger';
const winston = Logger.getWinstonInstance();