Enrich Distributed Tracing Context?

[matthieuauger]

Hello, this question may be an easy one but after a lot of research and back and forth I was not able to make it work.

I currently have a project with

• React-Router Framework (frontend, SSR)
• Express for my API

I setup the Tracing for both three layers and I have a nice tracing from my React pages to my Express api calls.
Now I would like to filter an Express api span with an attribute from React-Router.

To be more specific I would like to filter my Express API span traces on the User URL, which is an information I only have in my React-Router.
So if the user is on the /login page in React, find a way to set this context somewhere to be passed automatically on my express span traces with distributed tracing.

I tried to use the setTag, setExtra, setContext from Sentry SDK, but none of these attributes are passed to my Express API.

There may be a solution for me to manually add a custom HTTP header on every call to Express, but since we already automatically pass the trace-id and baggage with distributed tracing, is there a way to enrich this context to send it automatically to my API?

Thanks for you help