main: allow passing '--port' via command line

Allow user to control the Prometheus metrics port number. If non is
given, use default port-number.

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

Author: synarete

cmd/main.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	goruntime "runtime"
 
+	"github.com/spf13/pflag"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 
 	"github.com/samba-in-kubernetes/smbmetrics/internal/metrics"
@@ -23,6 +24,11 @@ func init() {
 }
 
 func main() {
+	var port int
+	pflag.IntVar(&port, "port", metrics.DefaultMetricsPort,
+		"Prometheus metrics-exporter port number")
+	pflag.Parse()
+
 	log := zap.New(zap.UseDevMode(true))
 	log.Info("Initializing smbmetrics",
 		"ProgramName", os.Args[0],
@@ -48,7 +54,7 @@ func main() {
 	}
 	log.Info("Located smbstatus", "path", loc, "version", ver)
 
-	err = metrics.RunSmbMetricsExporter(log, metrics.DefaultMetricsPort)
+	err = metrics.RunSmbMetricsExporter(log, port)
 	if err != nil {
 		os.Exit(1)
 	}

go.mod

@@ -5,6 +5,7 @@ go 1.16
 require (
 	github.com/go-logr/logr v0.4.0
 	github.com/prometheus/client_golang v1.11.1
+	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.7.0
 	k8s.io/api v0.22.2
 	k8s.io/apimachinery v0.22.2