add port derivation logic

Author: Xetera

internal/discovery/docker.go

@@ -354,7 +354,29 @@ func (w *DockerWatcher) DiscoverServiceInfo(svc DiscoveredService, onDiscovered
 			svc.Service = &services[0]
 		}
 
+		w.derivePorts(svc, services)
 		log.Printf("docker: discovered %d services for %s", len(services), svc.Subdomain)
 		onDiscovered(svc)
 	}()
 }
+
+func (*DockerWatcher) derivePorts(svc DiscoveredService, services []ServiceInfo) {
+	log.Printf("docker: before port selection for %s: port=%d, service=%v", svc.Subdomain, svc.Port, svc.Service)
+
+	if len(svc.Docker.Ports) > 1 {
+		isCurrentHTTP := svc.Service != nil && (svc.Service.Protocol == "http" || svc.Service.Protocol == "https")
+		if !isCurrentHTTP {
+			for _, s := range services {
+				if s.Protocol == "http" || s.Protocol == "https" {
+					oldPort := svc.Port
+					svc.Port = s.Port
+					svc.Service = &s
+					log.Printf("docker: using HTTP port %d instead of %d for %s", s.Port, oldPort, svc.Subdomain)
+					break a
+				}
+			}
+		}
+	}
+
+	log.Printf("docker: after port selection for %s: port=%d, service=%v", svc.Subdomain, svc.Port, svc.Service)
+}