fix: metric with services LB.

pkg/metrics/prometheus.go

@@ -229,11 +229,13 @@ func OnConfigurationUpdate(dynConf dynamic.Configurations, entryPoints []string)
 
 		for serviceName, service := range config.HTTP.Services {
 			dynamicConfig.services[fmt.Sprintf("%s@%s", serviceName, key)] = make(map[string]bool)
+			if service.LoadBalancer != nil {
 				for _, server := range service.LoadBalancer.Servers {
 					dynamicConfig.services[fmt.Sprintf("%s@%s", serviceName, key)][server.URL] = true
 				}
 			}
 		}
+	}
 
 	promState.SetDynamicConfig(dynamicConfig)
 }

pkg/metrics/prometheus_test.go

@@ -291,6 +291,11 @@ func TestPrometheusMetricRemoval(t *testing.T) {
 			th.WithLoadBalancerServices(th.WithService("bar",
 				th.WithServers(th.WithServer("http://localhost:9000"))),
 			),
+			func(cfg *dynamic.HTTPConfiguration) {
+				cfg.Services["fii"] = &dynamic.Service{
+					Weighted: &dynamic.WeightedRoundRobin{},
+				}
+			},
 		),
 	}