Make Prometheus cAdvisor metrics labels consistent

pkg/kubelet/cadvisor/cadvisor_linux.go

@@ -78,21 +78,29 @@ func init() {
 }
 
 func containerLabels(c *cadvisorapi.ContainerInfo) map[string]string {
-	set := map[string]string{metrics.LabelID: c.Name}
+	// Prometheus requires that all metrics in the same family have the same labels,
+	// so we arrange to supply blank strings for missing labels
+	var name, image, podName, namespace, containerName string
 	if len(c.Aliases) > 0 {
-		set[metrics.LabelName] = c.Aliases[0]
-	}
-	if image := c.Spec.Image; len(image) > 0 {
-		set[metrics.LabelImage] = image
+		name = c.Aliases[0]
 	}
+	image = c.Spec.Image
 	if v, ok := c.Spec.Labels[types.KubernetesPodNameLabel]; ok {
-		set["pod_name"] = v
+		podName = v
 	}
 	if v, ok := c.Spec.Labels[types.KubernetesPodNamespaceLabel]; ok {
-		set["namespace"] = v
+		namespace = v
 	}
 	if v, ok := c.Spec.Labels[types.KubernetesContainerNameLabel]; ok {
-		set["container_name"] = v
+		containerName = v
+	}
+	set := map[string]string{
+		metrics.LabelID:    c.Name,
+		metrics.LabelName:  name,
+		metrics.LabelImage: image,
+		"pod_name":         podName,
+		"namespace":        namespace,
+		"container_name":   containerName,
 	}
 	return set
 }

pkg/kubelet/server/server.go

@@ -813,21 +813,29 @@ func (a prometheusHostAdapter) GetMachineInfo() (*cadvisorapi.MachineInfo, error
 
 // containerPrometheusLabels maps cAdvisor labels to prometheus labels.
 func containerPrometheusLabels(c *cadvisorapi.ContainerInfo) map[string]string {
-	set := map[string]string{metrics.LabelID: c.Name}
+	// Prometheus requires that all metrics in the same family have the same labels,
+	// so we arrange to supply blank strings for missing labels
+	var name, image, podName, namespace, containerName string
 	if len(c.Aliases) > 0 {
-		set[metrics.LabelName] = c.Aliases[0]
-	}
-	if image := c.Spec.Image; len(image) > 0 {
-		set[metrics.LabelImage] = image
+		name = c.Aliases[0]
 	}
+	image = c.Spec.Image
 	if v, ok := c.Spec.Labels[kubelettypes.KubernetesPodNameLabel]; ok {
-		set["pod_name"] = v
+		podName = v
 	}
 	if v, ok := c.Spec.Labels[kubelettypes.KubernetesPodNamespaceLabel]; ok {
-		set["namespace"] = v
+		namespace = v
 	}
 	if v, ok := c.Spec.Labels[kubelettypes.KubernetesContainerNameLabel]; ok {
-		set["container_name"] = v
+		containerName = v
+	}
+	set := map[string]string{
+		metrics.LabelID:    c.Name,
+		metrics.LabelName:  name,
+		metrics.LabelImage: image,
+		"pod_name":         podName,
+		"namespace":        namespace,
+		"container_name":   containerName,
 	}
 	return set
 }