added version flag (fix: #25) (#26)

Author: mxschmitt

.travis.yml

@@ -30,7 +30,7 @@ before_deploy:
   # they failed to build.
   - go get github.com/mitchellh/gox
   - mkdir releases
-  - gox -osarch='!netbsd/arm !openbsd/386 !openbsd/amd64 !netbsd/386 !netbsd/amd64' -output="releases/{{.Dir}}_`git describe --tags --abbrev=0`_{{.OS}}_{{.Arch}}/{{.Dir}}"
+  - gox -osarch='!netbsd/arm !openbsd/386 !openbsd/amd64 !netbsd/386 !netbsd/amd64' -output="releases/{{.Dir}}_`git describe --tags --abbrev=0`_{{.OS}}_{{.Arch}}/{{.Dir}}" -ldflags "-X main.Version=`git describe --tags --abbrev=0`"
   # Loop through the built architecture directories and create their corresponding tar.gz archives with the binary in it.
   - find releases -maxdepth 2 -mindepth 2 -type f -exec bash -c 'tar -cvzf "$(dirname {}).tar.gz" -C "$(dirname {})" $(basename {})' \;
 

main.go

@@ -1,9 +1,22 @@
 package main
 
 import (
+	"flag"
+	"fmt"
+	"os"
+
 	"github.com/docker/machine/libmachine/drivers/plugin"
 )
 
+// Version will be added once we start the build process via travis-ci
+var Version string
+
 func main() {
+	version := flag.Bool("v", false, "prints current docker-machine-driver-hetzner version")
+	flag.Parse()
+	if *version {
+		fmt.Printf("Version: %s\n", Version)
+		os.Exit(0)
+	}
 	plugin.RegisterDriver(NewDriver())
 }