An example varnishd config virtual hosting backend services on localhost that are on non-standard ports, because memorizing ports for things is dumb (and so is /etc/services).

default.vcl

backend splunk{
    .host = "127.0.0.1";
    .port = "8000";
 }

backend archiveteam{
  .host = "127.0.0.1";
  .port = "8001";
}


sub vcl_recv{
  if (req.http.host ~ "(?i)^(splunk.)?home.grantstavely.com"){
    set req.backend = splunk;
  }

  if (req.http.host ~ "(?i)^(archiveteam.)?home.grantstavely.com"){
  set req.backend = znc;
  }
}