NodeJS ExpressJS - how to log errors for the production server?

Question

How can I log any errors from ExpressJS apps into a file?

I know I can log a Slim framework easily with monolog:

$app->get(\'/tickets\', function          


        

Answer 1

You can either add a logging library like morgan or if you have your node app running under a process manager, like pm2, then pm2 will keep track of the logging for you. I haven't used pm2 a ton, but from what I understand you could keep you console.log statements the same and pm2 will save all the output from your app into log files for you. You can read more about pm2's logging capabilities here.

Answer 2

you may feel irrelevant as PM2 is process manager but i found PM2 also best to deal error loggs.

Answer 3

winston is a popular library for logging.

You can transport all logs to one file or keep different files for error, debug and info logs.

Example:

  var winston = require('winston');

  var logger = new winston.Logger({
    level: 'error',
    transports: [
      new (winston.transports.File)({ filename: 'error.log' })
    ]
  });

In the code:

logger.log('error', 'test error message %s', 'my string');

You can also use winston daily rotate file with winston to rotate your log files based on size or date.