Wrong transaction name when multiple middlewares are using same variable in Express app

[Mordred]

Is there an existing issue for this?

• [X] I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• [X] I have reviewed the documentation https://docs.sentry.io/
• [X] I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Self-hosted/on-premise

Which SDK are you using?

@sentry/node

SDK Version

7.106.0

Framework Version

express@4.18.2

Link to Sentry event

No response

SDK Setup

Sentry.init({
  dsn: __DSN__,
  tracesSampleRate: 1.0,
  integrations: [
    new Sentry.Integrations.Express({ app }),
  ]
})

Steps to Reproduce

I have two middlewares with same variable but the second is more strict, because I need to do something for some languages. (https://replit.com/@jantosko/Sentry-Express-Transaction-Name#index.js)

const express = require('express');
const Sentry = require('@sentry/node');

const app = express();

Sentry.init({
  dsn: 'https://test@sentry.com/1',
  tracesSampleRate: 1.0,
  integrations: [
    new Sentry.Integrations.Express({ app }),
  ]
})

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

app.use('/:language/', (req, res, next) => {
  console.log(res.__sentry_transaction?.name)
  next();
});

app.use('/:language(sk|en)/', (req, res, next) => {
  console.log(res.__sentry_transaction?.name)
  next();
});

app.get('/:language/hello/', (req, res) => {
  console.log(res.__sentry_transaction?.name)
  res.send('Hello Express app!')
})

app.listen(3000, () => {
  console.log('server started');
})

When you hit /sk/hello/ the console output is:

GET /sk/hello/
GET /:language/:language

Expected Result

I expected that the transaction name will be GET /:language/hello/

Actual Result

Transaction name is GET /:language/:language :(

[Lms24]

Hey @Mordred thanks for writing in!

My hunch is that this is caused by our express router instrumentation that does a bunch of shady prototype patching to correctly parameterize a route name in time. The good news is that we're getting rid of all of this in favour of OpenTelemetry instrumentation. My hope is that their parameterization approach is much better than ours and problems like this one are going to be a thing of the past. This new instrumentation will be added in version 8 of our SDKs which we're working on right now.

We already shipped an alpha version: @sentry/node@8.0.0-alpha.2. If you're brave, feel free to give it a try ;) I'm curious if this fixes your issue.

[Lms24]

Btw, https://github.com/getsentry/sentry-javascript/issues/11023 sums up which frameworks and libraries will be instrumented automatically (via OpenTelemetry) in v8.

[Mordred]

OK, I will wait for at least beta release :)

[mydea]

We released v8.0.0, could you give it a try and let us know if it works as expected for you?

[getsantry[bot]]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you remove the label Waiting for: Community, I will leave it alone ... forever!

---

"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀

[indranuntd]

@mydea the issue is happening with v8 also. Tried with version 8.27.0.

[mydea]

@mydea the issue is happening with v8 also. Tried with version 8.27.0.

Do you mind creating a new issue with details of your (v8) setup and the problem you are seeing? That will make it easier for us to debug the problem - thank you!