How to flush winston logs?

Question

I want to flush the winston logger before process.exit.

process.on(\'uncaughtException\', function(err){
    logger.error(\'Fatal uncau         


        

Answer 1

Calling process.exit inside the log-callback like Thomas Heymann suggested will not ensure that the logs are actually flushed, especially when using a File-transport.

Instead of calling process.exit directly I would let the logger call process.exit after the log was flushed:

logger.js :

var winston = require('winston');

winston.loggers.add('my-logger', {
    console: {
        level: 'debug',
        colorize: true,
        timestamp: true,
        handleExceptions: true
    },
    file: {
        level: 'info',
        colorize: false,
        timestamp: true,
        filename: file,
        handleExceptions: true
    }
});

var logger = winston.loggers.get('my-logger');


/* ******* *
 * EXPORTS
 * ******* */

exports.exitAfterFlush = function(code) {
    logger.transports.file.on('flush', function() {
        process.exit(code);
    });
};

exports.info = function() {
    logger.info.apply(this, arguments);
};

exports.warn = function() {
    logger.info.apply(this, arguments);
};

exports.error = function() {
    logger.info.apply(this, arguments);
};

And in your code:

var logger = require('./logger.js');
logger.exitAfterFlush(0);
info('Done!');

Tested on NodeJS v4.1.2 and winston 1.1.0