Winston logger with added ability of namespacing and controlling severity levels with environment variables

logger.js

import winston, { format, createLogger, transports } from 'winston';
import DailyRotateFile from 'winston-daily-rotate-file';
const { combine, timestamp, label, printf } = format;

const formatConsoleMessage = printf((info) => {
  const { timestamp, label, level, message } = info;
  return `${timestamp} ${(level + ':').padEnd(16)} [${label}] ${message}`;
});

const logger = createLogger({
  level: 'info',
  format: format.json(),
  exitOnError: false,
  transports: [
    new winston.transports.DailyRotateFile({
      filename: './logs/combined-%DATE%.log',
      datePattern: 'YYYY-MM-DD',
      maxFiles: '14d',
    }),
  ],
});

if (process.env.NODE_ENV === 'development') {
  logger.level = process.env.LOG_LEVEL || 'debug';

  logger.add(
    new transports.Console({
      format: combine(
        format.colorize(),
        timestamp({
          format: 'YYYY-MM-DD HH:MM:SS',
        }),
        format.align(),
        formatConsoleMessage,
      ),
    }),
  );
}

// Amend the logger with namespacing via environment variables
// Inspiration: https://github.com/visionmedia/debug
// LOG=app:fetch – log only messages labeled with 'app:fetch'
// LOG=app:* – Log anything that starts with 'app:'; 'app:fetch', 'app:cache', etc.
// LOG=* – Log everyting
// LOG=*,-not_this – log everything but messages labeled with 'not_this'

/**
 * Check if the given label (namespace) is enabled through an environment variable.
 * Examples:
 *
 * @param {String} label – label of the message
 * @return {Boolean}
 *
 * */
const labelEnabled = (label) => {
  const setting = process.env.LOG;

  // Don't allow logging when no namespaces are specified
  if (typeof setting !== 'string') {
    return false;
  }

  // Split labels string into an array and convert '*' wildcards into valid JS regex
  const labels = setting.split(',').map((label) => label.replace(/\*/g, '.*?'));

  const included = labels.filter((label) => label[0] !== '-');
  const exluded = labels
    .filter((label) => label[0] === '-')
    .map((label) => label.substring(1));

  const includedMatch = included.find((lbl) =>
    new RegExp('^' + lbl + '$').test(label),
  );

  const excludedMatch = exluded.find((lbl) =>
    new RegExp('^' + lbl + '$').test(label),
  );

  if (excludedMatch) return false;
  if (includedMatch) return true;
};

export default (label) => {
  const log = (message, label, level) => {
    if (process.env.NODE_ENV !== 'production' && !labelEnabled(label)) {
      return;
    }

    logger.log({
      level,
      message,
      label,
    });
  };

  return Object.keys(logger.levels).reduce((acc, level) => {
    acc[level] = (message) => log(message, label, level);
    return acc;
  }, {});
};

There is error:

format: 'YYYY-MM-DD HH:MM:SS', // prints months / fractional seconds - https://momentjs.com/docs/#/parsing/string-format/

format: 'YYYY-MM-DD HH:mm:ss', // correct one