Add Prometheus exporter.

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
+}