dynamically set Callback URL Path based on incoming request?

[WalkerWalker]

my current traefik setup is

• traefik receives request at: Host(mydomain.com) && PathPrefix(/service_a)
• route to service_a@docker,
• and strip prefix /service_a
• same goes for /service_b, /service_c, etc

Now I want to use traefik-forward-auth to add an authentication middleware. Yet I notice that after success authentication, the redirect_uri is mydoamin.com/_oauth, would it be possible to redirect it to mydoamin.com/service_a ?