Need to identify the responding server from revers proxy

[jameskitterman]

Totally new to APISix. We are moving from Load balancing on a single server that was then going to 2 other servers which then had IIS doing reverse proxy and communicating with docker containers. So it was simple to add a fictitious response header for each responding server so that our support group is able to identify the server having an issue.

Now with APISix it is both the LB and reverse proxy so I am needing to somehow Identify the server that the response is coming from, and hopefully be able send a response header based on switch case logic because it needs to be fictitious header that support can cross reference.