CreateLogger.ts

import * as winston from  "winston";
import path from "path";
import DailyRotateFile from "winston-daily-rotate-file";
const { json, timestamp, combine } = winston.format;
const { Console } = winston.transports;

export default function CreateLogger(appName: string, nodeEnv: string, logFolder: string): winston.Logger {
	const dailyRotateFile: DailyRotateFile = new DailyRotateFile({
		filename: path.join(logFolder, `ui-${appName}-%DATE%.log`),
		datePattern: "YYYY-MM-DD-HH",
		maxSize: "20m",
		maxFiles: "14d",
		auditFile: path.join(logFolder, `ui-${appName}-audit.json`),
		format: combine(timestamp(), json()),
	});

	// do something when the files rotate
	// dailyRotateFile.on("rotate", function(oldFilename: string, newFilename: string) {
	// 	console.log(oldFilename, newFilename);
	// });

	const transports: winston.transport[] = [
		dailyRotateFile
	];

	// add "test" to provide a way to disable testing spam
	if (nodeEnv !== "production" && nodeEnv !== "test") {
		const consoleTransport = new Console({ format: winston.format.simple() });
		transports.push(consoleTransport);
	}

	return winston.createLogger({
		defaultMeta: { service: `ui-${appName}` },
		transports,
		exceptionHandlers: transports,
		rejectionHandlers: transports,
	});
}