Add Prometheus exporter.

Author: Xuewei Zhang

cmd/node_problem_detector.go

@@ -24,6 +24,7 @@ import (
 
 	"k8s.io/node-problem-detector/cmd/options"
 	"k8s.io/node-problem-detector/pkg/exporters/k8sexporter"
+	"k8s.io/node-problem-detector/pkg/exporters/prometheusexporter"
 	"k8s.io/node-problem-detector/pkg/problemdaemon"
 	"k8s.io/node-problem-detector/pkg/problemdetector"
 	"k8s.io/node-problem-detector/pkg/types"
@@ -57,6 +58,10 @@ func main() {
 		exporters = append(exporters, ke)
 		glog.Info("K8s exporter started.")
 	}
+	if pe := prometheusexporter.NewExporterOrDie(npdo); pe != nil {
+		exporters = append(exporters, pe)
+		glog.Info("Prometheus exporter started.")
+	}
 	if len(exporters) == 0 {
 		glog.Fatalf("No exporter is successfully setup")
 	}

cmd/options/options.go

@@ -52,6 +52,12 @@ type NodeProblemDetectorOptions struct {
 	// ApiServerOverride is the custom URI used to connect to Kubernetes ApiServer.
 	ApiServerOverride string
 
+	// prometheusExporter options
+	// PrometheusServerPort is the port to bind the Prometheus scrape endpoint. Use 0 to disable.
+	PrometheusServerPort int
+	// PrometheusServerAddress is the address to bind the Prometheus scrape endpoint.
+	PrometheusServerAddress string
+
 	// problem daemon options
 
 	// SystemLogMonitorConfigPaths specifies the list of paths to system log monitor configuration
@@ -96,6 +102,11 @@ func (npdo *NodeProblemDetectorOptions) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&npdo.ServerAddress, "address",
 		"127.0.0.1", "The address to bind the node problem detector server.")
 
+	fs.IntVar(&npdo.PrometheusServerPort, "prometheus-port",
+		20257, "The port to bind the Prometheus scrape endpoint. Prometheus exporter is enabled by default at port 20257. Use 0 to disable.")
+	fs.StringVar(&npdo.PrometheusServerAddress, "prometheus-address",
+		"127.0.0.1", "The address to bind the Prometheus scrape endpoint.")
+
 	for _, problemDaemonName := range problemdaemon.GetProblemDaemonNames() {
 		npdo.MonitorConfigPaths[problemDaemonName] = &[]string{}
 		fs.StringSliceVar(

pkg/exporters/prometheusexporter/prometheus_exporter.go

@@ -0,0 +1,60 @@
+/*
+Copyright 2019 The Kubernetes Authors 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 prometheusexporter
+
+import (
+	"net"
+	"net/http"
+	"strconv"
+
+	"contrib.go.opencensus.io/exporter/prometheus"
+	"github.com/golang/glog"
+	"go.opencensus.io/stats/view"
+
+	"k8s.io/node-problem-detector/cmd/options"
+	"k8s.io/node-problem-detector/pkg/types"
+)
+
+type prometheusExporter struct{}
+
+// NewExporterOrDie creates an exporter to export metrics to Prometheus, panics if error occurs.
+func NewExporterOrDie(npdo *options.NodeProblemDetectorOptions) types.Exporter {
+	if npdo.PrometheusServerPort <= 0 {
+		return nil
+	}
+
+	addr := net.JoinHostPort(npdo.PrometheusServerAddress, strconv.Itoa(npdo.PrometheusServerPort))
+	pe, err := prometheus.NewExporter(prometheus.Options{})
+	if err != nil {
+		glog.Fatalf("Failed to create Prometheus exporter: %v", err)
+	}
+	go func() {
+		mux := http.NewServeMux()
+		mux.Handle("/metrics", pe)
+		if err := http.ListenAndServe(addr, mux); err != nil {
+			glog.Fatalf("Failed to start Prometheus scrape endpoint: %v", err)
+		}
+	}()
+	view.RegisterExporter(pe)
+	return &prometheusExporter{}
+}
+
+// ExportProblems does nothing.
+// Prometheus exporter only exports metrics.
+func (pe *prometheusExporter) ExportProblems(status *types.Status) {
+	return
+}