node.js express request Id

Question

I'm trying to create some sort of a request Id for logging purposes which will be available to me through every function in the request flow. I want to log every step of the request flow with an Id stating which log line is for which request.

I've looked over some ideas and ran into 2 main suggestions:

The first is creating a middleware that will add a field in the 'req' object like so(as suggested here):

var logIdIterator = 0;

app.all('*', function(req, res, next) {
  req.log = {
    id: ++logIdIterator
  }
  return next();
});

And the second is using continuation-local-storage

The problems are:

For the first approach - it means I'll have to pass an extra argument to each function in the flow and this is not an easy solution to do over a mature application with countless APIs and flows.

The second one looks promising but unfortunately it has some issues where the state gets lost(see here for example). Also, it happened a few times when we used our redis library - which is bad because redis requests happen on each of our flows.

I guess if I don't find another solution, I'll have to use the first approach, it's just that I want to avoid passing an extra parameter to thousands of existing functions.

My question is - how do you suggest to maintain a request Id through the request flow?

Answer 1

You can use this package: https://www.npmjs.com/package/express-request-id

This is the middleware that will append uuid for every request

var app = require('express')();
var addRequestId = require('express-request-id')();
 
app.use(addRequestId);
 
app.get('/', function (req, res, next) {
    res.send(req.id);
    next();
});
 
app.listen(3000, function() {
    console.log('Listening on port %d', server.address().port);
});
 
// curl localhost:3000 
// d7c32387-3feb-452b-8df1-2d8338b3ea22