Dns_sd_config federation from IP targets behind proxies

I am attempting to use dns_sd_config. I have an A record that lists all of the IP addresses of the targets I want to federate from. However, the targets are each behind proxies that need a hostname sent along with each request.

From what I thought I understood, I can use tls_config: server_name to set a hostname header. However, the proxies are returning “503 Service Unavailable”, which makes me think perhaps Prometheus is not setting the “Host” header.

On IRC, @SuperQ suggested that I could try using SRV records if I am using host names. My response was that I have considered using SRV records. However, I am currently just doing a list of targets in static_configs with hostnames. I am trying to get away from needing a DNS name for each new cluster I need to federate from.

I guess my question would be, can Prometheus send a “Host” header to IP address targets?