Looking for way to add correlation ids

[pupca]

Hi,

I want to be able to add correlation ids to my app using express-zod-api.

My initial idea was to use express-http-context that would allow me to create a middleware such as

import { Request, Response, NextFunction } from 'express';
import { v4 } from 'uuid';
import * as httpContext from 'express-http-context';

export default async function requestId(req: Request, res: Response, next: NextFunction) {
  httpContext.ns.bindEmitter(req);
  httpContext.ns.bindEmitter(res);
  const id = v4();  
  httpContext.set('requestId', id);
  res.setHeader('request-id', id);
  console.log('request Id set is: ', httpContext.get('requestId'));
  return next();
}

This middleware would be added to my custom endpoint

export const jsonEndpointsFactory = new EndpointsFactory({
  resultHandler: defaultResultHandler,
  config,
})
  .addExpressMiddleware(cors({ credentials: true }))
  .addExpressMiddleware(requestId);

The problem is that the console output is

request Id set is: undefined

The ultimate goal is to have a custom formatter in my winston that would send the request id to Loki.

One suggestion is that it is caused by https://stackoverflow.com/questions/55611335/node-js-express-unable-to-retrieve-value-from-http-context-for-post-and-put-re/58546037#58546037

But i am not able to change the order of middleware's here :(

@RobinTail any idea what to do here, or how to achieve the ability to have a request id in my log classes?

Thanks

[RobinTail]

Hello @pupca .

Before I get to your actual question, I noticed something I'd like to suggest.
Consider replacing

.addExpressMiddleware(cors({ credentials: true }))

with an option in your config:

createConfig({
  cors: ({ defaultHeaders }) => ({ ...defaultHeaders, "Access-Control-Allow-Credentials": true })
})

It's acts the same, according to documentation and specification, but this way you can reduce your dependencies and keep the control on CORS headers in one place.

Regarding express-http-context I need a bit more time to explore the problem.

[RobinTail]

One suggestion is that it is caused by https://stackoverflow.com/questions/55611335/node-js-express-unable-to-retrieve-value-from-http-context-for-post-and-put-re/58546037#58546037
But i am not able to change the order of middleware's here :(

They recommend to place body parser before, but it's already before every .addExpressMiddleware() you're using.

[pupca]

@RobinTail first of all, thank you very much for looking into that!

I have modified the cors settings, thank you!

Perhaps you can think of any other solution that would make correlation id available from within logger classes...

[RobinTail]

@pupca , here is what I found out.
This solution works fine, when you apply the express-http-context middleware directly to express app (not by using .addExpressMiddleware).
Therefore, consider going with custom express app approach and attachRouting() method, described in the documentation, and applying the following lines to your own app:

import { v4 } from "uuid";
import * as httpContext from "express-http-context";

app.use(httpContext.middleware).use(({}, res, next) => {
    const requestId = v4();
    httpContext.set("requestId", requestId);
    console.log("the id", httpContext.get("requestId"));
    res.setHeader("x-request-id", requestId);
    next();
  });

I tested it and it works.

[pupca]

Thanks!

that looks good. I think i got it working too.

Thanks again!