feature: add version flag

Makefile

@@ -1,7 +1,13 @@
+TIMESTAMP = $(shell date +"%Y%m%d%H%M%S")
+BRANCH = $(shell git rev-parse --abbrev-ref HEAD 2>/dev/null)
+COMMIT = $(shell git rev-parse HEAD)
+VERSION = $(shell git describe --tags)
+LDFLAGSPREFIX = github.com/AliyunContainerService/image-syncer/pkg/utils
+LDFLAGS = "-X $(LDFLAGSPREFIX).Version=$(VERSION) -X $(LDFLAGSPREFIX).Branch=$(BRANCH) -X $(LDFLAGSPREFIX).Commit=$(COMMIT) -X $(LDFLAGSPREFIX).Timestamp=$(TIMESTAMP)"
 .PHONY: cmd clean
 
 cmd: $(wildcard ./pkg/client/*.go ./pkg/sync/*.go ./pkg/tools/*.go ./cmd/*.go ./*.go)
-	go build -o image-syncer ./main.go
+	go build -ldflags $(LDFLAGS) -o image-syncer ./main.go
 
 clean: 
 	rm image-syncer

cmd/image-syncer.go

@@ -17,7 +17,7 @@ var (
 
 	osFilterList, archFilterList []string
 
-	forceUpdate bool
+	forceUpdate, version bool
 )
 
 // RootCmd describes "image-syncer" command
@@ -31,6 +31,14 @@ var RootCmd = &cobra.Command{
 	RunE: func(cmd *cobra.Command, args []string) error {
 		cmd.SilenceErrors = true
 
+		if version {
+			fmt.Println("app-version: ", utils.Version)
+			fmt.Println("git-branch: ", utils.Branch)
+			fmt.Println("git-commit: ", utils.Commit)
+			fmt.Println("build-timestamp: ", utils.Timestamp)
+			return nil
+		}
+
 		// work starts here
 		client, err := client.NewSyncClient(configFile, authFile, imagesFile, logPath, successImagesFile, outputImagesFormat,
 			procNum, retries, utils.RemoveEmptyItems(osFilterList), utils.RemoveEmptyItems(archFilterList), forceUpdate)
@@ -55,6 +63,7 @@ func init() {
 	RootCmd.PersistentFlags().BoolVar(&forceUpdate, "force", false, "force update manifest whether the destination manifest exists")
 	RootCmd.PersistentFlags().StringVar(&successImagesFile, "output-success-images", "", "output success images in a new file")
 	RootCmd.PersistentFlags().StringVar(&outputImagesFormat, "output-images-format", "yaml", "success images output format, json or yaml")
+	RootCmd.PersistentFlags().BoolVar(&version, "version", false, "print app version")
 }
 
 // Execute executes the RootCmd

pkg/utils/version.go

@@ -0,0 +1,8 @@
+package utils
+
+var (
+	Version   = "v0.1.0"
+	Branch    = ""
+	Commit    = ""
+	Timestamp = ""
+)