Using Error report of Google Cloud Platform with ExpressJS

Question

I switched my ExpressJS application from Heroku to Google App Engine.
Everything works ok now.
But I am curious about how to debug my application if some exceptions happen on GAE.
On heroku, I can do heroku logs -t to trace the errors. I can check the variable printed by console.error(var) as well.
However, I don't know how to do the same thing on GAE.

I have checked logging of Stack Driver, it seems that it only shows some informations of every HTTP request instead of the detailed logs like heroku.
I have found that there is error report service of Stack Driver. It may what I want.
Here is the tutorial telling us how to setup. But the steps are confusing for me.
Does anyone have the experience to setup the error reporting?
I am finding a more clear steps to setup this.
Thanks a lot and appreciated!

Answer 1

For Stackdriver Error Reporting:

You can use code similar to the one advised for Google Compute Engine: https://cloud.google.com/error-reporting/docs/setup/compute-engine#send_exception_data

Here is what worked for me using Express and Winston on App Engine flexible environment:

var winston = require('winston');
winston.add(winston.transports.File, { filename: '/var/log/app_engine/custom_logs/my.errors.json' });

var report = function (err, req) {
  var payload = {
    serviceContext: {
      service: 'my service',
    },
    message: err.stack,
    context: {
      httpRequest: {
        url: req.originalUrl,
        method: req.method,
        referrer: req.header('Referer'),
        userAgent: req.header('User-Agent'),
        remoteIp: req.ip,
        responseStatusCode: 500,
      }
    }
  };
  winston.error (payload);
};

// Handle errors
app.use(function (err, req, res, next) {
  report(err, req);
  res.status(500).send(err.response || 'Something broke!');
});

For Stackdriver Logging:

Indeed, the request_log only contains HTTP requests log entries on App Engine flex. Look in the stdout log to see the output of your application.