Service Mirroring questions

Can anyone point me to any more information about service mirroring than what's in the docs, please?

I get the idea about service mirroring, and that it can be used to shadow a service with the same requests.

  1. Are these mirrored requests logged in the access logs?

  2. Is there a way to filter these requests, more than just a percentage? For example, only mirror the GET requests?

  3. Does Traefik send any sort of header to the mirrored service to let it know it's a mirror?

My main concern here is if the service requests aren't completely idempotent. Anything from a contact form that gets submitted twice to a credit card transaction that fails on the second try, how do we handle all that?

I found this, although there it's called "traffic shadowing", but it seems to go over some of the concerns I have:

It too mentions that it's important that the mirror knows it's a mirror. Does Traefik provide this option?