Winston/Node.js how add a Transport only for certain environment?

Question

I have the follow configuration:

var winston = require('winston');
var Mail = require('winston-mail').Mail;

var logger = new (winston.Logger)({
  transports: [
    new (winston.transports.Console)({ level: 'info', colorize: true }),
    new (winston.transports.File)({ level: 'info', filename: './logs/logs.log',
    new (Mail)({
              to: '[email protected]',
              from: '[email protected]',
              subject: 'Errors occurred',
              level: 'error',
              host: 'smtp.xxxxx.xx',
              username: '[email protected]', 
              password: 'xxxxx',
              port: xxx
            })
  ],
  exceptionHandlers: [
    new (winston.transports.Console)(),
    new (winston.transports.File)({ filename: './logs/exceptions.log' }),
    new (Mail)({
              to: '[email protected]',
              from: '[email protected]',
              subject: 'Errors occurred',
              level: 'error',
              host: 'smtp.xxxxx.xx',
              username: '[email protected]', 
              password: 'xxxxx',
              port: xxx
            })
 ]
});

I'd like add the Mail transport only for production environment not in staging or development.

I set a different log level as follow:

if (process.env.NODE_ENV === 'development') {
  logger.transports.console.level = 'debug';
  logger.transports.file.level = 'debug';
}

There is a way to do that also with transport?

Answer 1

The transports configuration is just a plain old Array. So we can use all the usual tricks on it. In this case, you want a conditional push().

const winston = require('winston');
const transports = [
    new winston.transports.Console({
        level    : 'info',
        colorize : true
    }),
    new winston.transports.File({
        level    : 'info',
        filename : './logs/logs.log'
    })
];

if (process.env.NODE_ENV === 'production') {
    const Mail = require('winston-mail').Mail;

    transports.push(new Mail({
        to       : '[email protected]',
        from     : '[email protected]',
        subject  : 'Errors occurred',
        level    : 'error',
        host     : 'smtp.xxxxx.xx',
        username : '[email protected]', 
        password : 'xxxxx',
        port     : 1234
    }));
}

const logger = new winston.Logger({
    transports
});

This code should be usable as is on Node.js >= 4, after filling in the mail configuration placeholders.

The same principle can be applied to the exceptionHandlers.