Dynamic backend host IP for subdomain traffic

Hello!

I need to create a backend for my service that will have a condition applied for it to be used whenever deals. is the subdomain of the host. I have that condition created and it looks like:

std.prefixof(req.http.host, "deals.")

I will have close to 100 domains I’m using and sending traffic to Fastly for. This is on a pinned service map, so I won’t be creating specific domains for this service. These domains don’t all use the same IP address for this host though, we have 5 different IPs for this traffic and there is a DNS entry for IP the domain should use on an A record.

I would like to configure a host to either send traffic from deals.mysite.com to the IP address configured on mybackendIP.mysite.com, or configure a dictionary on my service to lookup the IP address for the specified host.

I realize this is a strange and complicated ask. I guess my main question is if it’s even possible to do this, and which way would be the most straight forward? I’m open to really any solutions!

I was looking at Compute services and feel like these might do what i’m looking for but I’m not certain.

This could certainly be done in a Compute service, using a Config Store to hold the mappings from site name to origin DNS name (or IP address).