OvernightJS/logger

Despite the abundance of logging tools out there, knowing exactly which is the right one for your web-server, might take more time than you feel like spending. So you can start logging events right away, OvernightJS comes with its own logging package. From the environment variables you can easily switch your logs to be printed out to the command line, a file, or turned off completely. Logs printed to the console also are printed out in different colors depending on whether they're a warning, error, etc. The file for holdings logs can be specified manually or left as the default. Let's check it out!

Installation

$ npm install --save @overnightjs/logger

Guide

There's not as much to /logger as there was our for /core and /jwt, so we're just going to quickly go over what each method does and how to set it up. The logger package's main export is the Logger class. You will have separate instances of Logger throughout your project but they will all pull from the same environment-variables. The variables you need to set are the mode OVERNIGHT_LOGGER_MODE and the filepath OVERNIGHT_LOGGER_FILEPATH. The mode has 3 settings 'console', 'file', and 'off'. logger has an export LoggerModes which is an enum that provides all the modes if you want to use them in code. If you do not set the mode, logger will default to using CONSOLE. I would recommend using CONSOLE for local development, FILE for remote development, and OFF for production. If you want to change the settings in code, set the mode as the first argument to the constructor, and the filepath as the second.

Once you've setup logger there are 4 methods to print logs. They are info, which prints green, imp, which prints magenta, warn, which prints yellow, and err, which prints red. Each method must be passed the content to print as the first param. There is an optional second param which is a boolean. If you pass true as the second param, logger will use node's util so that the full object gets printed. You should NOT normally use this param, but it is especially useful when debugging errors so that you can print out the full error object and observe the stack trace.

logger will by default prepend every log with a datetime stamp. If you want to turn this off, set OVERNIGHT_LOGGER_RM_TIMESTAMP to "true" in the environment files or pass false as the third argument to the constructor. Like all other settings, the argument to the constructor, will override any environment settings.

One more thing, all settings have getter/setters so during development you can reconfigure them as needed.

Let's look at a code sample which sets the environment variables via a start script:

• In the start script

import * as path from 'path';
import * as fs from 'fs';
import { LoggerModes } from '@overnightjs/logger';

// Set the 
const logFilePath = path.join(__dirname, '../sampleProject.log');
process.env.OVERNIGHT_LOGGER_MODE = LoggerModes.FILE; // Can also be CONSOLE, or OFF
process.env.OVERNIGHT_LOGGER_FILEPATH = logFilePath;

// Remove current log file if it exists
(function removeFile() {
    try {
        fs.unlinkSync(logFilePath);
    } catch (e) { return; }
})();

• In the controller file

import { Request, Response } from 'express';
import { Controller, Get } from '@overnightjs/core';
import { Logger, LoggerModes } from '@overnightjs/logger';

@Controller('api/logger')
export class LoggerPracticeController {
    
    private readonly logger: Logger;
    
    constructor() {
        this.logger = new Logger();
    }

    @Get('console/:msg')
    private printLogsConsole(req: Request, res: Response): void {

        this.logger.info(req.params.msg);
        this.logger.imp(req.params.msg);
        this.logger.warn(req.params.msg);
        this.logger.err(req.params.msg);

        this.logger.err(new Error('printing out an error'));
        this.logger.err(new Error('printing out an error full'), true); // <-- print the full Error object

        res.status(200).json({msg: 'console_mode'});
    }
}

• The previous code-snippet will show the following content when printed to a file:

IMPORTANT: [2019-04-07T19:17:28.799Z]: OvernightJS with standard express router started on port: 3000
INFO: [2019-04-07T19:18:08.939Z]: hello-logger
IMPORTANT: [2019-04-07T19:18:08.939Z]: hello-logger
WARNING: [2019-04-07T19:18:08.939Z]: hello-logger
ERROR: [2019-04-07T19:18:08.940Z]: hello-logger
ERROR: [2019-04-07T19:18:08.940Z]: Error: printing out an error
ERROR: [2019-04-07T19:18:08.956Z]: Error: printing out an error full
    at class_1.LoggerPracticeController.printLogsFile (/home/seanmaxwell/WebstormProjects/Overnight/sample-project/src/controllers/LoggerPracticeController.ts:49:20)
    at class_1.descriptor.value [as printLogsFile] (/home/seanmaxwell/WebstormProjects/Overnight/src/core/lib/RouteDecorators.ts:36:35)
    at callBack (/home/seanmaxwell/WebstormProjects/Overnight/src/core/lib/Server.ts:78:50)
    at Layer.handle [as handle_request] (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/layer.js:95:5)
    at next (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/layer.js:95:5)
    at /home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:281:22
    at param (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:354:14)
    at param (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:365:14)
    at Function.process_params (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:410:3)
    at next (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:275:10)
    at Function.handle (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:174:3)
    at router (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:47:12)
    at Layer.handle [as handle_request] (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/home/seanmaxwell/WebstormProjects/Overnight/src/core/node_modules/express/lib/router/index.js:317:13)

• And this when printed to the console:

That's All!!

Please star this repo if you found it useful. Happy web-deving :)