Merge pull request #94 from rajaSahil/Expose-Metrics

feat(metrics): Expose LVM metrics

cmd/main.go

@@ -19,14 +19,15 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
+	"os"
+
 	config "github.com/openebs/lvm-localpv/pkg/config"
 	"github.com/openebs/lvm-localpv/pkg/driver"
 	"github.com/openebs/lvm-localpv/pkg/lvm"
 	"github.com/openebs/lvm-localpv/pkg/version"
 	"github.com/spf13/cobra"
 	"k8s.io/klog"
-	"log"
-	"os"
 )
 
 /*
@@ -37,6 +38,7 @@ import (
  * --plugin=controller and to start it as agent, we have
  * to pass --plugin=agent.
  */
+
 func main() {
 	_ = flag.CommandLine.Parse([]string{})
 	var config = config.Default()
@@ -83,6 +85,18 @@ func main() {
 		"Whether to set iops, bps rate limit for pods accessing volumes",
 	)
 
+	cmd.PersistentFlags().StringVar(
+		&config.ListenAddress, "listen-address", "", "The TCP network address where the prometheus metrics endpoint will listen (example: `:9080`). The default is empty string, which means metrics endpoint is disabled.",
+	)
+
+	cmd.PersistentFlags().StringVar(
+		&config.MetricsPath, "metrics-path", "/metrics", "The HTTP path where prometheus metrics will be exposed. Default is `/metrics`.",
+	)
+
+	cmd.PersistentFlags().BoolVar(
+		&config.DisableExporterMetrics, "disable-exporter-metrics", true, "Exclude metrics about the exporter itself (process_*, go_*).",
+	)
+
 	config.RIopsLimitPerGB = cmd.PersistentFlags().StringSlice(
 		"riops-per-gb", []string{},
 		"Read IOPS per GB limit to use for each volume group prefix, "+

go.mod

@@ -2,6 +2,8 @@ module github.com/openebs/lvm-localpv
 
 go 1.14
 
+replace google.golang.org/protobuf => google.golang.org/protobuf v1.25.0
+
 replace k8s.io/api => k8s.io/api v0.20.2
 
 replace k8s.io/apiextensions-apiserver => k8s.io/apiextensions-apiserver v0.20.2
@@ -61,10 +63,12 @@ require (
 	github.com/onsi/gomega v1.7.0
 	github.com/openebs/lib-csi v0.6.0
 	github.com/pkg/errors v0.9.1
+	github.com/prometheus/client_golang v1.11.0
+	github.com/prometheus/common v0.26.0 // indirect
 	github.com/spf13/cobra v1.1.1
 	github.com/stretchr/testify v1.6.1
 	golang.org/x/net v0.0.0-20201110031124-69a78807bb2b
-	golang.org/x/sys v0.0.0-20201112073958-5cba982894dd
+	golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40
 	google.golang.org/grpc v1.34.2
 	k8s.io/api v0.20.2
 	k8s.io/apimachinery v0.20.2

pkg/collector/collector.go

@@ -0,0 +1,78 @@
+/*
+Copyright 2021 The OpenEBS 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 collector
+
+import (
+	"github.com/openebs/lvm-localpv/pkg/lvm"
+	"github.com/prometheus/client_golang/prometheus"
+	"k8s.io/klog"
+)
+
+/*
+lvmCollector collects vg total size, vg free size and lv size metrics
+*/
+type lvmCollector struct {
+	vgFreeMetric *prometheus.Desc
+	vgSizeMetric *prometheus.Desc
+	lvSizeMetric *prometheus.Desc
+}
+
+func NewLvmCollector() prometheus.Collector {
+	return &lvmCollector{
+		vgFreeMetric: prometheus.NewDesc(prometheus.BuildFQName("lvm", "vg", "free_size_bytes"),
+			"LVM VG free size in bytes",
+			[]string{"name"}, nil,
+		),
+		vgSizeMetric: prometheus.NewDesc(prometheus.BuildFQName("lvm", "vg", "total_size_bytes"),
+			"LVM VG total size in bytes",
+			[]string{"name"}, nil,
+		),
+		// Metric name is openebs_size_of_volume which stores the size of lv
+		lvSizeMetric: prometheus.NewDesc(prometheus.BuildFQName("openebs", "size_of", "volume"),
+			"LVM LV total size in bytes",
+			[]string{"volumename", "device"}, nil,
+		),
+	}
+}
+
+func (c *lvmCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- c.vgFreeMetric
+	ch <- c.vgSizeMetric
+	ch <- c.lvSizeMetric
+}
+
+func (c *lvmCollector) Collect(ch chan<- prometheus.Metric) {
+	vgList, err := lvm.ListLVMVolumeGroup(false)
+	if err != nil {
+		klog.Errorf("error in getting the list of lvm volume groups: %v", err)
+	} else {
+		for _, vg := range vgList {
+			ch <- prometheus.MustNewConstMetric(c.vgFreeMetric, prometheus.GaugeValue, vg.Free.AsApproximateFloat64(), vg.Name)
+			ch <- prometheus.MustNewConstMetric(c.vgSizeMetric, prometheus.GaugeValue, vg.Size.AsApproximateFloat64(), vg.Name)
+		}
+	}
+
+	lvList, err := lvm.ListLVMLogicalVolume()
+	if err != nil {
+		klog.Errorf("error in getting the list of lvm logical volumes: %v", err)
+	} else {
+		for _, lv := range lvList {
+			ch <- prometheus.MustNewConstMetric(c.lvSizeMetric, prometheus.GaugeValue, float64(lv.Size), lv.Name, lv.Device)
+
+		}
+	}
+}

pkg/config/config.go

@@ -69,6 +69,16 @@ type Config struct {
 	// WBpsLimitPerGB provides read bps rate limits per volume group type
 	// as a string slice, in the form ["vg1-prefix=100", "vg2-prefix=200"]
 	WBpsLimitPerGB *[]string
+
+	// The TCP network address where the prometheus metrics endpoint will listen (example: `:9080`).
+	// The default is empty string, which means metrics endpoint is disabled.
+	ListenAddress string
+
+	// The HTTP path where prometheus metrics will be exposed. Default is `/metrics`.
+	MetricsPath string
+
+	// Exclude metrics about the exporter itself (process_*, go_*).
+	DisableExporterMetrics bool
 }
 
 // Default returns a new instance of config

pkg/driver/agent.go

@@ -18,9 +18,15 @@ package driver
 
 import (
 	"errors"
+	"net/http"
 	"strings"
 	"sync"
 
+	"github.com/openebs/lvm-localpv/pkg/collector"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"github.com/openebs/lib-csi/pkg/btrfs"
 	k8sapi "github.com/openebs/lib-csi/pkg/client/k8s"
@@ -79,11 +85,93 @@ func NewNode(d *CSIDriver) csi.NodeServer {
 		}
 	}()
 
+	if d.config.ListenAddress != "" {
+		exposeMetrics(d.config.ListenAddress, d.config.MetricsPath, d.config.DisableExporterMetrics)
+	}
+
 	return &node{
 		driver: d,
 	}
 }
 
+//Function to register collectors to collect LVM related metrics and exporter metrics.
+//
+//If disableExporterMetrics is set to false, exporter will include metrics about itself i.e (process_*, go_*).
+func registerCollectors(disableExporterMetrics bool) (*prometheus.Registry, error) {
+	registry := prometheus.NewRegistry()
+
+	if !disableExporterMetrics {
+		processCollector := collectors.NewProcessCollector(collectors.ProcessCollectorOpts{})
+		err := registry.Register(processCollector)
+		if err != nil {
+			klog.Errorf("failed to register process collector for exporter metrics collection: %s", err.Error())
+			return nil, err
+		}
+		goProcessCollector := collectors.NewGoCollector()
+		err = registry.Register(goProcessCollector)
+		if err != nil {
+			klog.Errorf("failed to register go process collector for exporter metrics collection: %s", err.Error())
+			return nil, err
+		}
+	}
+	lvmCollector := collector.NewLvmCollector()
+
+	err := registry.Register(lvmCollector)
+	if err != nil {
+		klog.Errorf("failed to register LVM collector for LVM metrics collection: %s", err.Error())
+		return nil, err
+	}
+	return registry, nil
+}
+
+type promLog struct{}
+
+// Implementation of Println(...) method of Logger interface of prometheus client_go.
+func (p *promLog) Println(v ...interface{}) {
+	klog.Error(v...)
+}
+
+func promLogger() *promLog {
+	return &promLog{}
+}
+
+//Function to start HTTP server to expose LVM metrics.
+//
+//Parameters:
+//
+//listenAddr: TCP network address where the prometheus metrics endpoint will listen.
+//
+//metricsPath: The HTTP path where prometheus metrics will be exposed.
+//
+//disableExporterMetrics: Exclude metrics about the exporter itself (process_*, go_*).
+func exposeMetrics(listenAddr string, metricsPath string, disableExporterMetrics bool) {
+
+	// Registry with all the collectors registered
+	registry, err := registerCollectors(disableExporterMetrics)
+	if err != nil {
+		klog.Fatalf("Failed to register collectors for LVM metrics collection: %s", err.Error())
+	}
+
+	http.Handle(metricsPath, promhttp.InstrumentMetricHandler(registry, promhttp.HandlerFor(registry, promhttp.HandlerOpts{
+		ErrorLog: promLogger(),
+	})))
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`<html>
+			<head><title>LVM Exporter</title></head>
+			<body>
+			<h1>LVM Exporter</h1>
+			<p><a href="` + metricsPath + `">Metrics</a></p>
+			</body>
+			</html>`))
+	})
+
+	go func() {
+		if err := http.ListenAndServe(listenAddr, nil); err != nil {
+			klog.Fatalf("Failed to start HTTP server at specified address (%q) and metrics path (%q) to expose LVM metrics: %s", listenAddr, metricsPath, err.Error())
+		}
+	}()
+}
+
 // GetVolAndMountInfo get volume and mount info from node csi volume request
 func GetVolAndMountInfo(
 	req *csi.NodePublishVolumeRequest,