Filter internal Kubernetes labels from Prometheus metrics

Kubernetes uses Docker labels as storage for some internal labels. The
majority of these labels are not meaningful metric labels and a few of
them are even harmful as they're not static and cause wrong aggregation
results.

This change provides a custom labels func to only attach meaningful
labels to cAdvisor exported metrics.

pkg/kubelet/cadvisor/cadvisor_linux.go

@@ -33,7 +33,9 @@ import (
 	cadvisorapi "github.com/google/cadvisor/info/v1"
 	cadvisorapiv2 "github.com/google/cadvisor/info/v2"
 	"github.com/google/cadvisor/manager"
+	"github.com/google/cadvisor/metrics"
 	"github.com/google/cadvisor/utils/sysfs"
+	"k8s.io/kubernetes/pkg/kubelet/types"
 	"k8s.io/kubernetes/pkg/util/runtime"
 )
 
@@ -70,7 +72,27 @@ func init() {
 	}
 }
 
-// Creates a cAdvisor and exports its API on the specified port if port > 0.
+func containerLabels(c *cadvisorapi.ContainerInfo) map[string]string {
+	set := map[string]string{metrics.LabelID: c.Name}
+	if len(c.Aliases) > 0 {
+		set[metrics.LabelName] = c.Aliases[0]
+	}
+	if image := c.Spec.Image; len(image) > 0 {
+		set[metrics.LabelImage] = image
+	}
+	if v, ok := c.Spec.Labels[types.KubernetesPodNameLabel]; ok {
+		set["pod_name"] = v
+	}
+	if v, ok := c.Spec.Labels[types.KubernetesPodNamespaceLabel]; ok {
+		set["namespace"] = v
+	}
+	if v, ok := c.Spec.Labels[types.KubernetesContainerNameLabel]; ok {
+		set["container_name"] = v
+	}
+	return set
+}
+
+// New creates a cAdvisor and exports its API on the specified port if port > 0.
 func New(port uint, runtime string) (Interface, error) {
 	sysFs, err := sysfs.NewRealSysFs()
 	if err != nil {
@@ -108,7 +130,7 @@ func (cc *cadvisorClient) exportHTTP(port uint) error {
 		return err
 	}
 
-	cadvisorhttp.RegisterPrometheusHandler(mux, cc, "/metrics", nil)
+	cadvisorhttp.RegisterPrometheusHandler(mux, cc, "/metrics", containerLabels)
 
 	// Only start the http server if port > 0
 	if port > 0 {

pkg/kubelet/cadvisor/cadvisor_linux_test.go

@@ -0,0 +1,65 @@
+// +build cgo,linux
+
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cadvisor
+
+import (
+	"reflect"
+	"testing"
+
+	info "github.com/google/cadvisor/info/v1"
+	"github.com/google/cadvisor/metrics"
+	"k8s.io/kubernetes/pkg/kubelet/types"
+)
+
+func TestContainerLabels(t *testing.T) {
+	container := &info.ContainerInfo{
+		ContainerReference: info.ContainerReference{
+			Name:    "/docker/f81ad5335d390944e454ea19ab0924037d57337c19731524ad96eb26e74b6c6d",
+			Aliases: []string{"k8s_POD.639b2af2_foo-web-315473031-e40e2_foobar_a369ace2-5fa9-11e6-b10f-c81f66e5e84d_851a97fd"},
+		},
+		Spec: info.ContainerSpec{
+			Image: "qux/foo:latest",
+			Labels: map[string]string{
+				"io.kubernetes.container.hash":                   "639b2af2",
+				types.KubernetesContainerNameLabel:               "POD",
+				"io.kubernetes.container.restartCount":           "0",
+				"io.kubernetes.container.terminationMessagePath": "",
+				types.KubernetesPodNameLabel:                     "foo-web-315473031-e40e2",
+				types.KubernetesPodNamespaceLabel:                "foobar",
+				"io.kubernetes.pod.terminationGracePeriod":       "30",
+				types.KubernetesPodUIDLabel:                      "a369ace2-5fa9-11e6-b10f-c81f66e5e84d",
+			},
+			Envs: map[string]string{
+				"foo+env": "prod",
+			},
+		},
+	}
+	want := map[string]string{
+		metrics.LabelID:    "/docker/f81ad5335d390944e454ea19ab0924037d57337c19731524ad96eb26e74b6c6d",
+		metrics.LabelName:  "k8s_POD.639b2af2_foo-web-315473031-e40e2_foobar_a369ace2-5fa9-11e6-b10f-c81f66e5e84d_851a97fd",
+		metrics.LabelImage: "qux/foo:latest",
+		"namespace":        "foobar",
+		"container_name":   "POD",
+		"pod_name":         "foo-web-315473031-e40e2",
+	}
+
+	if have := containerLabels(container); !reflect.DeepEqual(want, have) {
+		t.Errorf("want %v, have %v", want, have)
+	}
+}