node.js - PM2 log uncaught exceptions to third-party service (as Logentries)

Question

I'm using pm2 (https://github.com/Unitech/pm2) in my node.js project. Also I'm sending logs of errors of the app in Logentries (https://logentries.com).

I wonder is it possible to log uncaught exceptions from the app (when something fails badly and pm2 restarts the app for example)? I know that using process.on('uncaughtException') is bad practice so would like to hear some suggestions.

Thanks!

Frangipani

Answer 1

Where did you read that process.on('uncaughtException') is a bad practice?

As long as you exit the process after logging the exception I don't see what's bad, here is an example:

process.on('uncaughtException', function(e) {
    console.error('Ouch, an unhandled exception');
    //I like using new Error() for my errors (1)
    console.error(e instanceof Error ? e.message : e);
    process.exit(1);
});

(1): Javascript Error reference

Edit pm2-interface is now deprecated, use require('pm2') instead. You will be able to do exactly the same as below by using bus system events.

---

An alternative with pm2 is to use pm2-interface and listening to the process:exit or process:exception events:

var ipm2 = require('pm2-interface')();

ipm2.on('ready', function() {
  console.log('Connected to pm2');

  ipm2.bus.on('process:exception', function(data){
    console.log(data.pm2_env.name + 'had an exception');
  });
});

This is really usefull when managing more than one process through a monitoring process.

You might want to check the blog post on how to build a custom pm2 logger. It can give you some ideas about monitoring processes through pm2-interface.

Cadwell

From the npm docs: 'uncaughtException' is a crude mechanism for exception handling intended to be used only as a last resort nodejs.org/api/… – Inessive

It is not a good practice for production process to catch and resolve exceptions. However if you want to catch errors while remotely monitoring/debugging, it is useful – Kriemhild

Your link "bus system events" is broken – Bouffant