Merge pull request #30638 from krousey/metrics_registration

Automatic merge from submit-queue

Remove implicit Prometheus metrics from client

**What this PR does / why we need it**: This PR starts to cut away at dependencies that the client has.

**Release note**:
<!--  Steps to write your release note:
1. Use the release-note-* labels to set the release note state (if you have access) 
2. Enter your extended release note in the below block; leaving it blank means using the PR title as the release note. If no release note is required, just write `NONE`. 
-->
```release-note
The implicit registration of Prometheus metrics for request count and latency have been removed, and a plug-able interface was added. If you were using our client libraries in your own binaries and want these metrics, add the following to your imports in the main package: "k8s.io/pkg/client/metrics/prometheus". 
```

cc: @kubernetes/sig-api-machinery @kubernetes/sig-instrumentation @fgrzadkowski  @wojtek-t

cmd/hyperkube/main.go

@@ -23,6 +23,8 @@ package main
 
 import (
 	"os"
+
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 )
 
 func main() {

cmd/kube-apiserver/apiserver.go

@@ -26,6 +26,7 @@ import (
 
 	"k8s.io/kubernetes/cmd/kube-apiserver/app"
 	"k8s.io/kubernetes/cmd/kube-apiserver/app/options"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/util/flag"
 	"k8s.io/kubernetes/pkg/util/logs"
 	"k8s.io/kubernetes/pkg/version/verflag"

cmd/kube-controller-manager/controller-manager.go

@@ -26,6 +26,7 @@ import (
 
 	"k8s.io/kubernetes/cmd/kube-controller-manager/app"
 	"k8s.io/kubernetes/cmd/kube-controller-manager/app/options"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/healthz"
 	"k8s.io/kubernetes/pkg/util/flag"
 	"k8s.io/kubernetes/pkg/util/logs"

cmd/kube-dns/dns.go

@@ -20,6 +20,7 @@ import (
 	"github.com/spf13/pflag"
 	"k8s.io/kubernetes/cmd/kube-dns/app"
 	"k8s.io/kubernetes/cmd/kube-dns/app/options"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/util/flag"
 	"k8s.io/kubernetes/pkg/util/logs"
 	"k8s.io/kubernetes/pkg/version/verflag"

cmd/kube-proxy/proxy.go

@@ -22,6 +22,7 @@ import (
 
 	"k8s.io/kubernetes/cmd/kube-proxy/app"
 	"k8s.io/kubernetes/cmd/kube-proxy/app/options"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/healthz"
 	"k8s.io/kubernetes/pkg/util/flag"
 	"k8s.io/kubernetes/pkg/util/logs"

cmd/kubectl/app/kubectl.go

@@ -19,6 +19,7 @@ package app
 import (
 	"os"
 
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/kubectl/cmd"
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 	"k8s.io/kubernetes/pkg/util/logs"

cmd/kubelet/kubelet.go

@@ -26,6 +26,7 @@ import (
 
 	"k8s.io/kubernetes/cmd/kubelet/app"
 	"k8s.io/kubernetes/cmd/kubelet/app/options"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/util/flag"
 	"k8s.io/kubernetes/pkg/util/logs"
 	"k8s.io/kubernetes/pkg/version/verflag"

cmd/kubemark/hollow-node.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 
 	"k8s.io/kubernetes/pkg/api"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 	"k8s.io/kubernetes/pkg/client/record"
 	client "k8s.io/kubernetes/pkg/client/unversioned"
 	clientset "k8s.io/kubernetes/pkg/client/unversioned/adapters/internalclientset"

contrib/mesos/cmd/km/km.go

@@ -19,6 +19,8 @@ package main
 
 import (
 	"os"
+
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 )
 
 func main() {

hack/.linted_packages

@@ -74,6 +74,8 @@ pkg/apis/imagepolicy/install
 pkg/api/v1
 pkg/auth/authenticator
 pkg/auth/authorizer/union
+pkg/client/metrics
+pkg/client/metrics/prometheus
 pkg/client/testing/core
 pkg/client/unversioned
 pkg/client/unversioned/adapters/internalclientset

pkg/client/metrics/metrics.go

@@ -14,54 +14,48 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// Package metrics provides utilities for registering client metrics to Prometheus.
+// Package metrics provides abstractions for registering which metrics
+// to record.
 package metrics
 
 import (
+	"net/url"
 	"sync"
 	"time"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-const restClientSubsystem = "rest_client"
-
-var (
-	// RequestLatency is a Prometheus Summary metric type partitioned by
-	// "verb" and "url" labels. It is used for the rest client latency metrics.
-	RequestLatency = prometheus.NewSummaryVec(
-		prometheus.SummaryOpts{
-			Subsystem: restClientSubsystem,
-			Name:      "request_latency_microseconds",
-			Help:      "Request latency in microseconds. Broken down by verb and URL",
-			MaxAge:    time.Hour,
-		},
-		[]string{"verb", "url"},
-	)
-
-	RequestResult = prometheus.NewCounterVec(
-		prometheus.CounterOpts{
-			Subsystem: restClientSubsystem,
-			Name:      "request_status_codes",
-			Help:      "Number of http requests, partitioned by metadata",
-		},
-		[]string{"code", "method", "host"},
-	)
 )
 
 var registerMetrics sync.Once
 
-// Register registers all metrics to Prometheus with
-// respect to the RequestLatency.
-func Register() {
-	// Register the metrics.
+// LatencyMetric observes client latency partitioned by verb and url.
+type LatencyMetric interface {
+	Observe(verb string, u url.URL, latency time.Duration)
+}
+
+// ResultMetric counts response codes partitioned by method and host.
+type ResultMetric interface {
+	Increment(code string, method string, host string)
+}
+
+var (
+	// RequestLatency is the latency metric that rest clients will update.
+	RequestLatency LatencyMetric = noopLatency{}
+	// RequestResult is the result metric that rest clients will update.
+	RequestResult ResultMetric = noopResult{}
+)
+
+// Register registers metrics for the rest client to use. This can
+// only be called once.
+func Register(lm LatencyMetric, rm ResultMetric) {
 	registerMetrics.Do(func() {
-		prometheus.MustRegister(RequestLatency)
-		prometheus.MustRegister(RequestResult)
+		RequestLatency = lm
+		RequestResult = rm
 	})
 }
 
-// Calculates the time since the specified start in microseconds.
-func SinceInMicroseconds(start time.Time) float64 {
-	return float64(time.Since(start).Nanoseconds() / time.Microsecond.Nanoseconds())
-}
+type noopLatency struct{}
+
+func (noopLatency) Observe(string, url.URL, time.Duration) {}
+
+type noopResult struct{}
+
+func (noopResult) Increment(string, string, string) {}

pkg/client/metrics/prometheus/prometheus.go

@@ -0,0 +1,76 @@
+/*
+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 prometheus creates and registers prometheus metrics with
+// rest clients. To use this package, you just have to import it.
+package prometheus
+
+import (
+	"net/url"
+	"time"
+
+	"k8s.io/kubernetes/pkg/client/metrics"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const restClientSubsystem = "rest_client"
+
+var (
+	// requestLatency is a Prometheus Summary metric type partitioned by
+	// "verb" and "url" labels. It is used for the rest client latency metrics.
+	requestLatency = prometheus.NewSummaryVec(
+		prometheus.SummaryOpts{
+			Subsystem: restClientSubsystem,
+			Name:      "request_latency_microseconds",
+			Help:      "Request latency in microseconds. Broken down by verb and URL",
+			MaxAge:    time.Hour,
+		},
+		[]string{"verb", "url"},
+	)
+
+	requestResult = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Subsystem: restClientSubsystem,
+			Name:      "request_status_codes",
+			Help:      "Number of http requests, partitioned by metadata",
+		},
+		[]string{"code", "method", "host"},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(requestLatency)
+	prometheus.MustRegister(requestResult)
+	metrics.Register(&latencyAdapter{requestLatency}, &resultAdapter{requestResult})
+}
+
+type latencyAdapter struct {
+	m *prometheus.SummaryVec
+}
+
+func (l *latencyAdapter) Observe(verb string, u url.URL, latency time.Duration) {
+	microseconds := float64(latency) / float64(time.Microsecond)
+	l.m.WithLabelValues(verb, u.String()).Observe(microseconds)
+}
+
+type resultAdapter struct {
+	m *prometheus.CounterVec
+}
+
+func (r *resultAdapter) Increment(code, method, host string) {
+	r.m.WithLabelValues(code, method, host).Inc()
+}

pkg/client/restclient/request.go

@@ -58,10 +58,6 @@ var (
 	longThrottleLatency = 50 * time.Millisecond
 )
 
-func init() {
-	metrics.Register()
-}
-
 // HTTPClient is an interface for testing a request object.
 type HTTPClient interface {
 	Do(req *http.Request) (*http.Response, error)
@@ -609,7 +605,7 @@ func (r *Request) URL() *url.URL {
 // underyling object.  This means some useful request info (like the types of field
 // selectors in use) will be lost.
 // TODO: preserve field selector keys
-func (r Request) finalURLTemplate() string {
+func (r Request) finalURLTemplate() url.URL {
 	if len(r.resourceName) != 0 {
 		r.resourceName = "{name}"
 	}
@@ -622,7 +618,8 @@ func (r Request) finalURLTemplate() string {
 		newParams[k] = v
 	}
 	r.params = newParams
-	return r.URL().String()
+	url := r.URL()
+	return *url
 }
 
 func (r *Request) tryThrottle() {
@@ -697,10 +694,10 @@ func updateURLMetrics(req *Request, resp *http.Response, err error) {
 
 	// If we have an error (i.e. apiserver down) we report that as a metric label.
 	if err != nil {
-		metrics.RequestResult.WithLabelValues(err.Error(), req.verb, url).Inc()
+		metrics.RequestResult.Increment(err.Error(), req.verb, url)
 	} else {
 		//Metrics for failure codes
-		metrics.RequestResult.WithLabelValues(strconv.Itoa(resp.StatusCode), req.verb, url).Inc()
+		metrics.RequestResult.Increment(strconv.Itoa(resp.StatusCode), req.verb, url)
 	}
 }
 
@@ -775,7 +772,7 @@ func (r *Request) request(fn func(*http.Request, *http.Response)) error {
 	//Metrics for total request latency
 	start := time.Now()
 	defer func() {
-		metrics.RequestLatency.WithLabelValues(r.verb, r.finalURLTemplate()).Observe(metrics.SinceInMicroseconds(start))
+		metrics.RequestLatency.Observe(r.verb, r.finalURLTemplate(), time.Since(start))
 	}()
 
 	if r.err != nil {

pkg/client/restclient/request_test.go

@@ -331,7 +331,8 @@ func TestURLTemplate(t *testing.T) {
 	if full.String() != "http://localhost/pre1/namespaces/ns/r1/nm?p0=v0" {
 		t.Errorf("unexpected initial URL: %s", full)
 	}
-	actual := r.finalURLTemplate()
+	actualURL := r.finalURLTemplate()
+	actual := actualURL.String()
 	expected := "http://localhost/pre1/namespaces/%7Bnamespace%7D/r1/%7Bname%7D?p0=%7Bvalue%7D"
 	if actual != expected {
 		t.Errorf("unexpected URL template: %s %s", actual, expected)