Adding image pull latency metric.

Also adding TODOs for other metrics.

Part of #4604.

pkg/kubelet/kubelet.go

@@ -38,6 +38,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/record"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/envvars"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/metrics"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/volume"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/probe"
@@ -964,6 +965,11 @@ func (kl *Kubelet) createPodInfraContainer(pod *api.BoundPod) (dockertools.Docke
 }
 
 func (kl *Kubelet) pullImage(img string, ref *api.ObjectReference) error {
+	start := time.Now()
+	defer func() {
+		metrics.ImagePullLatency.Observe(float64(time.Since(start).Nanoseconds() / time.Microsecond.Nanoseconds()))
+	}()
+
 	if err := kl.dockerPuller.Pull(img); err != nil {
 		if ref != nil {
 			record.Eventf(ref, "failed", "Failed to pull image %q", img)

pkg/kubelet/metrics/metrics.go

@@ -0,0 +1,59 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+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 metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const kubeletSubsystem = "kubelet"
+
+var (
+	ImagePullLatency = prometheus.NewSummary(
+		prometheus.SummaryOpts{
+			Subsystem: kubeletSubsystem,
+			Name:      "image_pull_latency_microseconds",
+			Help:      "Image pull latency in microseconds.",
+		},
+	)
+	// TODO(vmarmol): Implement.
+	// TODO(vmarmol): Split by source?
+	PodCount = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Subsystem: kubeletSubsystem,
+			Name:      "pod_count",
+			Help:      "Number of pods currently running.",
+		},
+	)
+	// TODO(vmarmol): Implement.
+	// TODO(vmarmol): Split by source?
+	ContainerCount = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Subsystem: kubeletSubsystem,
+			Name:      "container_count",
+			Help:      "Number of containers currently running.",
+		},
+	)
+	// TODO(vmarmol): Containers per pod
+	// TODO(vmarmol): Latency of pod startup
+	// TODO(vmarmol): Latency of SyncPods
+)
+
+func init() {
+	// Register the metrics.
+	prometheus.MustRegister(ImagePullLatency)
+}