added version command

cmd/root.go

@@ -5,12 +5,16 @@ import (
 	"log"
 	"os"
 	"path"
+	"strings"
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
+	"github.com/xenolf/lego/acme"
 )
 
+var gittag string
 var cfgFile string
+var version string
 var Logger *log.Logger
 
 func logger() *log.Logger {
@@ -41,6 +45,13 @@ func Execute() {
 
 func init() {
 	cobra.OnInitialize(initConfig)
+    
+	version = "0.3.0"
+	if strings.HasPrefix(gittag, "v") {
+		version = gittag
+	}
+
+	acme.UserAgent = "lego/" + version
 	cwd, err := os.Getwd()
 	if err != nil {
 		logger().Fatal("Could not determine current working directory. Please pass --path.")

cmd/version.go

@@ -0,0 +1,36 @@
+// Copyright © 2016 NAME HERE <EMAIL ADDRESS>
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// versionCmd represents the version command
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "Prints current version of lego",
+	Long: ``,
+	Run: func(cmd *cobra.Command, args []string) {
+		// TODO: Work your own magic here
+		fmt.Println("lego version", version)
+	},
+}
+
+func init() {
+	RootCmd.AddCommand(versionCmd)
+}