Add version command

cmd/flagger/main.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"log"
+	"os"
 	"strings"
 	"time"
 
@@ -39,6 +41,7 @@ var (
 	namespace           string
 	meshProvider        string
 	selectorLabels      string
+	ver                 bool
 )
 
 func init() {
@@ -57,11 +60,17 @@ func init() {
 	flag.StringVar(&namespace, "namespace", "", "Namespace that flagger would watch canary object.")
 	flag.StringVar(&meshProvider, "mesh-provider", "istio", "Service mesh provider, can be istio, appmesh, supergloo, nginx or smi.")
 	flag.StringVar(&selectorLabels, "selector-labels", "app,name,app.kubernetes.io/name", "List of pod labels that Flagger uses to create pod selectors.")
+	flag.BoolVar(&ver, "version", false, "Print version")
 }
 
 func main() {
 	flag.Parse()
 
+	if ver {
+		fmt.Println("Flagger version", version.VERSION, "revision ", version.REVISION)
+		os.Exit(0)
+	}
+
 	logger, err := logger.NewLoggerWithEncoding(logLevel, zapEncoding)
 	if err != nil {
 		log.Fatalf("Error creating logger: %v", err)