Node: custom onFatalError does not work

[OliverJAsh]

• Review the documentation: https://docs.sentry.io/
• Search for existing issues: https://github.com/getsentry/sentry-javascript/issues
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Package + Version

• @sentry/browser
• @sentry/node
• raven-js
• raven-node (raven for node)
• other:

Version:

4.6.3

Description

I am providing a custom onFatalError to Sentry for Node:

import * as Sentry from '@sentry/node';

const options: Sentry.NodeOptions = {
  // …
  onFatalError: error => {
    console.error('Test onFatalError')
    console.error(error)
  },
  // …
};
Sentry.init(options);

However, when a fatal exception occurs, the default handler is used instead.

I stepped into the code and discovered that when we construct OnUncaughtException, we forget to pass in options:

https://github.com/getsentry/sentry-javascript/blob/4.6.3/packages/node/src/sdk.ts#L18

Thus, options.onFatalError is always undefined:

https://github.com/getsentry/sentry-javascript/blob/4.6.3/packages/node/src/integrations/onuncaughtexception.ts#L20-L23

I'm surprised TypeScript didn't catch this bug at compile time?

[OliverJAsh]

Hi, do you have any thoughts on this? It's currently blocking us from upgrading.

[HazAT]

@OliverJAsh Oh, good catch, we will fix this, thank you.
As a workaround you could do this:

Sentry.init({
  ...
  integrations: [
    new Sentry.Integrations.OnUncaughtException({
      onFatalError: error => {
        console.error('Test onFatalError');
        console.error(error);
      },
    }),
  ],
  ...
});

[MatteoGioioso]

@HazAT Hello is this fixed?

This morning we discovered a fatal error not reported by Sentry

Is this the correct setup?

Sentry.init({
  dsn: process.env.SENTRY_DNS,
  integrations: [new Sentry.Integrations.OnUncaughtException()]
});

or fatal errors must have additional configuration?

[kamilogorek]

There's no need to attach OnUncaughtException integration, as it's default and should work just fine without it.

[MatteoGioioso]

I just tested it again and Sentry cannot caught Fatal error. I have simulated an out of memory error with the following configuration

Sentry.init({
  dsn: "https://[email protected]/id",
});

const app = express();

app.use(Sentry.Handlers.requestHandler());

// routes

app.use(Sentry.Handlers.errorHandler());

// Global error handler
app.use(function(err, req, res, next) {

Sentry version: 5.11.0

The result is that I cannot see anything logged in Sentry.

[kamilogorek]

Can you set debug: true in your init call and see if you get any valuable logs? If not, are you able to provide a repro case for it?

[MatteoGioioso]

I think I can try to reproduce it, hopefully I am doing something wrong, should I open a new issue?

[kamilogorek]

No need , I'll reopen this one

[MatteoGioioso]

OK, I have managed to make something: https://github.com/MatteoGioioso/sentry-fatal-error
It have basically simulated an out of memory error that make the app crash.

Please, first of all make sure that I did not make any mistakes in the Sentry configuration, that is the exact config that we have on our server right now, thanks!

[kamilogorek]

It's not a node exception in this case. It's a process crashing, which produces a core dump (if env is configured appropriately). There is no way for the VM to call any of the handlers when it's out of memory. You can easily confirm this by adding this snippet at the very start of your program. It won't trigger.

process.on('exit', (code) => {
  console.log(`About to exit with code: ${code}`);
});

Please refer to https://www.javascriptjanuary.com/blog/nodejs-postmortem-debugging-for-fun-and-production on how to debug such issues. Cheers!