Prevent crash of application after Error: getaddrinfo ENOTFOUND at GetAddrInfoReqWrap.onlookup

I'm using Node.js 7.8.0 and I'm trying to send HTTP-request to some host, sometimes the desired host doesn't exist. In such case, I get the following message:

events.js:163
      throw er; // Unhandled 'error' event
      ^

Error: getaddrinfo ENOTFOUND js.js js.js:80
    at errnoException (dns.js:28:10)
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:73:26)

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where js.js is the demo of non existent host. It's important to note, that everything works correctly if I send the same request to the existing host.

The problem is that this error leads to crash of my Node.js application, while I need to keep the app running.

I already checked, my HTTP-request doesn't contain http/https/port in the field of host.

I tried to use try/catch, domains, and res.on('error', exitHandlerCB) approaches, nothing works. The only way that worked for me is process.on('uncaughtException', exitHandlerCB);, but this one leads to the stop of my Node.js app.

Is there any way to catch the error due to request to non existing host and to continue the application flow?

Solution

Is there any way to catch the error due to request to non existing host and to continue the application flow?

Yes, what you need is listening error event on request object. Example code would be:

let http = require('http');

let clientRequest = http.get({
  hostname: 'www.not-exist-i9io90o9i8.com',
  port: 80,
  path: '/'
}, function (res) {
  console.log(res);
});
clientRequest.on('error', function(){
  console.log('error handler');
});

//...further operation

According to Node.js http document:

If any error is encountered during the request (be that with DNS resolution, TCP level errors, or actual HTTP parse errors) an 'error' event is emitted on the returned request object. As with all 'error' events, if no listeners are registered the error will be thrown.

The error catched in your case is error with DNS resolution.