Merge pull request #4612 from tomwilkie/dns-controller-metrics

Export kubernetes client metrics from dns-controller.

dns-controller/cmd/dns-controller/BUILD.bazel

@@ -18,9 +18,11 @@ go_library(
         "//protokube/pkg/gossip/dns/provider:go_default_library",
         "//protokube/pkg/gossip/mesh:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/prometheus/client_golang/prometheus/promhttp:go_default_library",
         "//vendor/github.com/spf13/pflag:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/k8s.io/client-go/rest:go_default_library",
+        "//vendor/k8s.io/kubernetes/pkg/client/metrics/prometheus:go_default_library",
     ],
 )
 

dns-controller/cmd/dns-controller/main.go

@@ -21,14 +21,18 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"log"
+	"net/http"
 	"os"
 	"strings"
 
 	"github.com/golang/glog"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/pflag"
 
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
+	_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
 
 	"k8s.io/kops/dns-controller/pkg/dns"
 	"k8s.io/kops/dns-controller/pkg/watchers"
@@ -50,7 +54,7 @@ var (
 
 func main() {
 	fmt.Printf("dns-controller version %s\n", BuildVersion)
-	var dnsServer, dnsProviderID, gossipListen, gossipSecret, watchNamespace string
+	var dnsServer, dnsProviderID, gossipListen, gossipSecret, watchNamespace, metricsListen string
 	var gossipSeeds, zones []string
 	var watchIngress bool
 
@@ -66,6 +70,7 @@ func main() {
 	flags.StringVar(&gossipSecret, "gossip-secret", gossipSecret, "Secret to use to secure gossip")
 	flags.StringVar(&watchNamespace, "watch-namespace", "", "Limits the functionality for pods, services and ingress to specific namespace, by default all")
 	flag.IntVar(&route53.MaxBatchSize, "route53-batch-size", route53.MaxBatchSize, "Maximum number of operations performed per changeset batch")
+	flag.StringVar(&metricsListen, "metrics-listen-addr", ":3999", "The address on which to listen for Prometheus metrics.")
 
 	// Trick to avoid 'logging before flag.Parse' warning
 	flag.CommandLine.Parse([]string{})
@@ -74,6 +79,11 @@ func main() {
 	flags.AddGoFlagSet(flag.CommandLine)
 	flags.Parse(os.Args)
 
+	go func() {
+		http.Handle("/metrics", promhttp.Handler())
+		log.Fatal(http.ListenAndServe(metricsListen, nil))
+	}()
+
 	zoneRules, err := dns.ParseZoneRules(zones)
 	if err != nil {
 		glog.Errorf("unexpected zone flags: %q", err)