Merge pull request #1226 from munnerz/acme-client-metrics

Add prometheus metrics for ACME client HTTP requests

pkg/acme/acme.go

@@ -157,7 +157,7 @@ func (h *helperImpl) ClientForIssuer(iss cmapi.GenericIssuer) (acme.Interface, e
 // In future, we may change to having two global HTTP clients - one that ignores
 // TLS connection errors, and the other that does not.
 func buildHTTPClient(skipTLSVerify bool) *http.Client {
-	return &http.Client{
+	return acme.NewInstrumentedClient(&http.Client{
 		Transport: &http.Transport{
 			Proxy:                 http.ProxyFromEnvironment,
 			DialContext:           dialTimeout,
@@ -168,7 +168,7 @@ func buildHTTPClient(skipTLSVerify bool) *http.Client {
 			ExpectContinueTimeout: 1 * time.Second,
 		},
 		Timeout: time.Second * 30,
-	}
+	})
 }
 
 var timeout = time.Duration(5 * time.Second)

pkg/acme/client/BUILD.bazel

@@ -4,11 +4,15 @@ go_library(
     name = "go_default_library",
     srcs = [
         "fake.go",
+        "http.go",
         "interfaces.go",
     ],
     importpath = "github.com/jetstack/cert-manager/pkg/acme/client",
     visibility = ["//visibility:public"],
-    deps = ["//third_party/crypto/acme:go_default_library"],
+    deps = [
+        "//pkg/metrics:go_default_library",
+        "//third_party/crypto/acme:go_default_library",
+    ],
 )
 
 filegroup(

pkg/acme/client/http.go

@@ -0,0 +1,108 @@
+/*
+Copyright 2019 The Jetstack cert-manager contributors.
+
+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 client
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/jetstack/cert-manager/pkg/metrics"
+)
+
+// This file implements a custom instrumented HTTP client round tripper that
+// exposes prometheus metrics for each endpoint called.
+//
+// We implement this as part of the HTTP client to ensure we don't miss any
+// calls made to the ACME server caused by retries in the underlying ACME
+// library.
+
+// Transport is a http.RoundTripper that collects Prometheus metrics of every
+// request it processes. It allows to be configured with callbacks that process
+// request path and query into a suitable label value.
+type Transport struct {
+	next http.RoundTripper
+}
+
+// pathProcessor will trim the provided path to only include the first 2
+// segments in order to reduce the number of prometheus labels generated
+func pathProcessor(path string) string {
+	p := strings.Split(path, "/")
+	// only record the first two path segments as a prometheus label value
+	if len(p) > 3 {
+		p = p[:3]
+	}
+	return strings.Join(p, "/")
+}
+
+// RoundTrip implements http.RoundTripper. It forwards the request to the
+// next RoundTripper and measures the time it took in Prometheus summary.
+func (it *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
+	statusCode := 999
+
+	// Remember the current time.
+	now := time.Now()
+
+	// Make the request using the next RoundTripper.
+	resp, err := it.next.RoundTrip(req)
+	if resp != nil {
+		statusCode = resp.StatusCode
+	}
+
+	labels := []string{
+		req.URL.Scheme,
+		req.URL.Host,
+		pathProcessor(req.URL.Path),
+		req.Method,
+		fmt.Sprintf("%d", statusCode),
+	}
+	// Observe the time it took to make the request.
+	metrics.Default.ACMEClientRequestDurationSeconds.
+		WithLabelValues(labels...).
+		Observe(time.Since(now).Seconds())
+
+	metrics.Default.ACMEClientRequestCount.
+		WithLabelValues(labels...).Inc()
+
+	// return the response and error reported from the next RoundTripper.
+	return resp, err
+}
+
+// NewInstrumentedClient takes a *http.Client and returns a *http.Client that
+// has its RoundTripper wrapped with instrumentation.
+func NewInstrumentedClient(next *http.Client) *http.Client {
+	// If next client is not defined we'll use http.DefaultClient.
+	if next == nil {
+		next = http.DefaultClient
+	}
+
+	next.Transport = newTransport(next.Transport)
+
+	return next
+}
+
+// NewTransport takes a http.RoundTripper, wraps it with instrumentation and
+// returns it as a new http.RoundTripper.
+func newTransport(next http.RoundTripper) http.RoundTripper {
+	// If next RoundTripper is not defined we'll use http.DefaultTransport.
+	if next == nil {
+		next = http.DefaultTransport
+	}
+
+	return &Transport{next: next}
+}

pkg/metrics/metrics.go

@@ -61,12 +61,39 @@ var CertificateExpiryTimeSeconds = prometheus.NewGaugeVec(
 	[]string{"name", "namespace"},
 )
 
+// ACMEClientRequestCount is a Prometheus summary to collect the number of
+// requests made to each endpoint with the ACME client.
+var ACMEClientRequestCount = prometheus.NewCounterVec(
+	prometheus.CounterOpts{
+		Namespace: namespace,
+		Name:      "acme_client_request_count",
+		Help:      "The number of requests made by the ACME client.",
+		Subsystem: "http",
+	},
+	[]string{"scheme", "host", "path", "method", "status"},
+)
+
+// ACMEClientRequestDurationSeconds is a Prometheus summary to collect request
+// times for the ACME client.
+var ACMEClientRequestDurationSeconds = prometheus.NewSummaryVec(
+	prometheus.SummaryOpts{
+		Namespace:  namespace,
+		Name:       "acme_client_request_duration_seconds",
+		Help:       "The HTTP request latencies in seconds for the ACME client.",
+		Subsystem:  "http",
+		Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+	},
+	[]string{"scheme", "host", "path", "method", "status"},
+)
+
 type Metrics struct {
 	http.Server
 
 	// TODO (@dippynark): switch this to use an interface to make it testable
-	registry                     *prometheus.Registry
-	CertificateExpiryTimeSeconds *prometheus.GaugeVec
+	registry                         *prometheus.Registry
+	CertificateExpiryTimeSeconds     *prometheus.GaugeVec
+	ACMEClientRequestDurationSeconds *prometheus.SummaryVec
+	ACMEClientRequestCount           *prometheus.CounterVec
 }
 
 func New() *Metrics {
@@ -82,8 +109,10 @@ func New() *Metrics {
 			MaxHeaderBytes: prometheusMetricsServerMaxHeaderBytes,
 			Handler:        router,
 		},
-		registry:                     prometheus.NewRegistry(),
-		CertificateExpiryTimeSeconds: CertificateExpiryTimeSeconds,
+		registry:                         prometheus.NewRegistry(),
+		CertificateExpiryTimeSeconds:     CertificateExpiryTimeSeconds,
+		ACMEClientRequestDurationSeconds: ACMEClientRequestDurationSeconds,
+		ACMEClientRequestCount:           ACMEClientRequestCount,
 	}
 
 	router.Handle("/metrics", promhttp.HandlerFor(s.registry, promhttp.HandlerOpts{}))
@@ -107,8 +136,9 @@ func (m *Metrics) waitShutdown(stopCh <-chan struct{}) {
 }
 
 func (m *Metrics) Start(stopCh <-chan struct{}) {
-
 	m.registry.MustRegister(m.CertificateExpiryTimeSeconds)
+	m.registry.MustRegister(m.ACMEClientRequestDurationSeconds)
+	m.registry.MustRegister(m.ACMEClientRequestCount)
 
 	go func() {