Use established pattern for kubelet metrics url

Signed-off-by: Davanum Srinivas <[email protected]>

Author: dims

test/e2e_node/container_metrics_test.go

@@ -26,6 +26,7 @@ import (
 	"github.com/onsi/gomega/gstruct"
 	"github.com/onsi/gomega/types"
 
+	"k8s.io/kubernetes/pkg/cluster/ports"
 	"k8s.io/kubernetes/test/e2e/framework"
 	e2emetrics "k8s.io/kubernetes/test/e2e/framework/metrics"
 	e2evolume "k8s.io/kubernetes/test/e2e/framework/volume"
@@ -125,7 +126,7 @@ var _ = SIGDescribe("ContainerMetrics", "[LinuxOnly]", framework.WithNodeConform
 
 func getContainerMetrics(ctx context.Context) (e2emetrics.KubeletMetrics, error) {
 	ginkgo.By("getting container metrics from cadvisor")
-	return e2emetrics.GrabKubeletMetricsWithoutProxy(ctx, framework.TestContext.NodeName+":10255", "/metrics/cadvisor")
+	return e2emetrics.GrabKubeletMetricsWithoutProxy(ctx, fmt.Sprintf("%s:%d", nodeNameOrIP(), ports.KubeletReadOnlyPort), "/metrics/cadvisor")
 }
 
 func preciseSample(value interface{}) types.GomegaMatcher {