main: allow passing --address to set bind address

cmd/main.go

@@ -3,6 +3,7 @@
 package main
 
 import (
+	"net"
 	"os"
 	goruntime "runtime"
 
@@ -27,6 +28,9 @@ func main() {
 	var port int
 	pflag.IntVar(&port, "port", metrics.DefaultMetricsPort,
 		"Prometheus metrics-exporter port number")
+	var bindAddress net.IP
+	pflag.IPVar(&bindAddress, "address", bindAddress,
+		"Prometheus metrics-exporter bind address")
 	var noProfile bool
 	pflag.BoolVar(&noProfile, "no-profile", false,
 		"Run without collecting profile information")
@@ -57,7 +61,12 @@ func main() {
 	}
 	log.Info("Located smbstatus", "path", loc, "version", ver)
 
-	err = metrics.RunSmbMetricsExporter(log, port, !noProfile)
+	var bindAddrs []net.IP
+	if len(bindAddress) > 0 {
+		bindAddrs = append(bindAddrs, bindAddress)
+		log.Info("User supplied bind addresses", "bindAddrs", bindAddrs)
+	}
+	err = metrics.RunSmbMetricsExporter(log, port, bindAddrs, !noProfile)
 	if err != nil {
 		os.Exit(1)
 	}

internal/metrics/exporter.go

@@ -20,20 +20,23 @@ var (
 )
 
 type smbMetricsExporter struct {
-	log     logr.Logger
-	reg     *prometheus.Registry
-	mux     *http.ServeMux
-	port    int
-	profile bool
+	log           logr.Logger
+	reg           *prometheus.Registry
+	mux           *http.ServeMux
+	port          int
+	bindAddresses []net.IP
+	profile       bool
 }
 
-func newSmbMetricsExporter(log logr.Logger, port int, profile bool) *smbMetricsExporter {
+func newSmbMetricsExporter(
+	log logr.Logger, port int, bindAddresses []net.IP, profile bool) *smbMetricsExporter {
 	return &smbMetricsExporter{
-		log:     log,
-		reg:     prometheus.NewRegistry(),
-		mux:     http.NewServeMux(),
-		port:    port,
-		profile: profile,
+		log:           log,
+		reg:           prometheus.NewRegistry(),
+		mux:           http.NewServeMux(),
+		port:          port,
+		bindAddresses: bindAddresses,
+		profile:       profile,
 	}
 }
 
@@ -43,7 +46,15 @@ func (sme *smbMetricsExporter) init() error {
 }
 
 func (sme *smbMetricsExporter) serve() error {
-	addr := fmt.Sprintf(":%d", sme.port)
+	var addr string
+	switch len(sme.bindAddresses) {
+	case 0:
+		addr = fmt.Sprintf(":%d", sme.port)
+	case 1:
+		addr = fmt.Sprintf("%s:%d", sme.bindAddresses[0], sme.port)
+	default:
+		return fmt.Errorf("too many listen addresses")
+	}
 	sme.log.Info("serve metrics", "addr", addr)
 
 	handler := promhttp.HandlerFor(sme.reg, promhttp.HandlerOpts{})
@@ -65,11 +76,12 @@ func (sme *smbMetricsExporter) serve() error {
 
 // RunSmbMetricsExporter executes an HTTP server and exports SMB metrics to
 // Prometheus.
-func RunSmbMetricsExporter(log logr.Logger, port int, profile bool) error {
+func RunSmbMetricsExporter(
+	log logr.Logger, port int, bindAddresses []net.IP, profile bool) error {
 	if port <= 0 {
 		port = DefaultMetricsPort
 	}
-	sme := newSmbMetricsExporter(log, port, profile)
+	sme := newSmbMetricsExporter(log, port, bindAddresses, profile)
 	err := sme.init()
 	if err != nil {
 		return err