metrics: collect and export smb metrics via prometheus

Using 'smbstatus' collect shares and locks  metrics end export it via
Prometheus.

Signed-off-by: Shachar Sharon <[email protected]>

Author: synarete

internal/metrics/collectors.go

@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	collectorsNamespace = "smb"
+)
+
+func (sme *smbMetricsExporter) register() error {
+	cols := []prometheus.Collector{
+		sme.newSmbSharesCollector(),
+		sme.newSmbLocksCollector(),
+	}
+	for _, c := range cols {
+		if err := sme.reg.Register(c); err != nil {
+			sme.log.Error(err, "failed to register collector")
+			return err
+		}
+	}
+	return nil
+}
+
+type smbCollector struct {
+	// nolint:structcheck
+	sme *smbMetricsExporter
+	dsc []*prometheus.Desc
+}
+
+func (col *smbCollector) Describe(ch chan<- *prometheus.Desc) {
+	for _, d := range col.dsc {
+		ch <- d
+	}
+}
+
+type smbSharesCollector struct {
+	smbCollector
+}
+
+func (col *smbSharesCollector) Collect(ch chan<- prometheus.Metric) {
+	sharesTotal := 0
+	sharesMap, _ := SmbStatusSharesByMachine()
+	for machine, share := range sharesMap {
+		sharesCount := len(share)
+		ch <- prometheus.MustNewConstMetric(col.dsc[0],
+			prometheus.GaugeValue, float64(sharesCount), machine)
+		sharesTotal += sharesCount
+	}
+
+	ch <- prometheus.MustNewConstMetric(col.dsc[1],
+		prometheus.GaugeValue, float64(sharesTotal))
+}
+
+func (sme *smbMetricsExporter) newSmbSharesCollector() prometheus.Collector {
+	col := &smbSharesCollector{}
+	col.sme = sme
+	col.dsc = []*prometheus.Desc{
+		prometheus.NewDesc(
+			collectorName("shares", "machine"),
+			"Number of shares by host-machine ip",
+			[]string{"machine"}, nil),
+
+		prometheus.NewDesc(
+			collectorName("shares", "total"),
+			"Total number of active shares",
+			[]string{}, nil),
+	}
+	return col
+}
+
+type smbLocksCollector struct {
+	smbCollector
+}
+
+func (col *smbLocksCollector) Collect(ch chan<- prometheus.Metric) {
+	locks, _ := RunSmbStatusLocks()
+	ch <- prometheus.MustNewConstMetric(col.dsc[0],
+		prometheus.GaugeValue, float64(len(locks)))
+}
+
+func (sme *smbMetricsExporter) newSmbLocksCollector() prometheus.Collector {
+	col := &smbLocksCollector{}
+	col.sme = sme
+	col.dsc = []*prometheus.Desc{
+		prometheus.NewDesc(
+			collectorName("locks", "total"),
+			"Total number of active locks",
+			[]string{}, nil),
+	}
+	return col
+}
+
+func collectorName(subsystem, name string) string {
+	return prometheus.BuildFQName(collectorsNamespace, subsystem, name)
+}

internal/metrics/exporter.go

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package metrics
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+
+	"github.com/go-logr/logr"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var (
+	// DefaultMetricsPort is the default port used to export prometheus metrics
+	DefaultMetricsPort = int(8080)
+	// DefaultMetricsPath is the default HTTP path to export prometheus metrics
+	DefaultMetricsPath = "/metrics"
+)
+
+type smbMetricsExporter struct {
+	log  logr.Logger
+	reg  *prometheus.Registry
+	mux  *http.ServeMux
+	port int
+}
+
+func newSmbMetricsExporter(log logr.Logger, port int) *smbMetricsExporter {
+	return &smbMetricsExporter{
+		log:  log,
+		reg:  prometheus.NewRegistry(),
+		mux:  http.NewServeMux(),
+		port: port,
+	}
+}
+
+func (sme *smbMetricsExporter) init() error {
+	sme.log.Info("register collectors")
+	return sme.register()
+}
+
+func (sme *smbMetricsExporter) serve() error {
+	addr := fmt.Sprintf(":%d", sme.port)
+	sme.log.Info("serve metrics", "addr", addr)
+
+	handler := promhttp.HandlerFor(sme.reg, promhttp.HandlerOpts{})
+	sme.mux.Handle(DefaultMetricsPath, handler)
+
+	listener, err := net.Listen("tcp", addr)
+	if err != nil {
+		sme.log.Error(err, "failed to listen", "addr", addr)
+		return err
+	}
+	defer listener.Close()
+
+	if err := http.Serve(listener, sme.mux); err != nil {
+		sme.log.Error(err, "HTTP server failure", "addr", addr)
+		return err
+	}
+	return nil
+}
+
+// RunSmbMetricsExporter executes an HTTP server and exports SMB metrics to
+// Prometheus.
+func RunSmbMetricsExporter(log logr.Logger) error {
+	sme := newSmbMetricsExporter(log, DefaultMetricsPort)
+	err := sme.init()
+	if err != nil {
+		return err
+	}
+	return sme.serve()
+}