[SOLVED] Request header field sentry-trace is not allowed by Access-Control-Allow-Headers in preflight response

Request header field sentry-trace is not allowed by Access-Control-Allow-Headers in preflight response

I'm developing a Frontend using NextJS and Keycloak for auth-purpose. After adding Sentry, I'm facing this issue here, where the token endpoint of Keycloak is returning an error; So I can log in.

I've tried many things:

Change the web-origin config of Keycloak, which (obviously) doesn't change or solves the problem
Play with the Sentry client config, without success, because the denyUrls property still make the Sentry SDK send the sentry-trace into the request.

Now I don't have any more Idea, so I coming here for more help.

Solution

So after some investigations, I came across this tracingOrigins property that can be set using integrations like this:

integrations: [
    new (Sentry.Integrations as any).BrowserTracing({
        tracingOrigins: [
            process.env.NEXT_PUBLIC_URL,
            process.env.NEXT_PUBLIC_BACKEND_URL,
            process.env.NEXT_PUBLIC_MATOMO_URL,
        ],
    }),
],

This config is done inside the sentry.client.config.ts file. The downside is that, urls which are not included there, are simply not tracked.