add -v option to print version number

Author: lalyos

Makefile

@@ -1,16 +1,16 @@
 NAME=dockerhook
 HARDWARE=$(shell uname -m)
-VERSION=0.1.0
+VERSION=0.1.1
 
 build:
 	go get || true && go build
 
 release:
 	rm -rf release
 	mkdir release
-	GOOS=linux go build -o release/$(NAME)
+	GOOS=linux go build -ldflags "-X main.Version=$(VERSION)" -o release/$(NAME)
 	cd release && tar -zcf $(NAME)_$(VERSION)_linux_$(HARDWARE).tgz $(NAME)
-	GOOS=darwin go build -o release/$(NAME)
+	GOOS=darwin go build -ldflags "-X main.Version=$(VERSION)" -o release/$(NAME)
 	cd release && tar -zcf $(NAME)_$(VERSION)_darwin_$(HARDWARE).tgz $(NAME)
 	rm release/$(NAME)
 	echo "$(VERSION)" > release/version

dockerhook.go

@@ -18,6 +18,9 @@ import (
 
 var debug = flag.Bool("d", false, "debug mode displays handler output")
 var shell = flag.Bool("s", false, "run handler via SHELL")
+var printVerrion = flag.Bool("v", false, "print version and exit")
+
+var Version string
 
 var skipInspect = map[string]bool{
 	"destroy": true,
@@ -99,6 +102,11 @@ func trigger(hook []string, event, id string, docker *dockerapi.Client) {
 
 func main() {
 	flag.Parse()
+	if *printVerrion {
+		fmt.Println("version:", Version)
+		os.Exit(0)
+	}
+
 	if flag.NArg() < 1 {
 		flag.Usage()
 		os.Exit(64)