Added version checker on startup

cmd/headscale/cli/version.go

@@ -2,11 +2,12 @@ package cli
 
 import (
 	"fmt"
-	"github.com/spf13/cobra"
 	"strings"
+
+	"github.com/spf13/cobra"
 )
 
-var version = "dev"
+var Version = "dev"
 
 func init() {
 	rootCmd.AddCommand(versionCmd)
@@ -19,9 +20,9 @@ var versionCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 		o, _ := cmd.Flags().GetString("output")
 		if strings.HasPrefix(o, "json") {
-			JsonOutput(map[string]string{"version": version}, nil, o)
+			JsonOutput(map[string]string{"version": Version}, nil, o)
 			return
 		}
-		fmt.Println(version)
+		fmt.Println(Version)
 	},
 }

cmd/headscale/headscale.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"time"
 
@@ -9,6 +10,7 @@ import (
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 	"github.com/spf13/viper"
+	"github.com/tcnksm/go-latest"
 )
 
 func main() {
@@ -38,6 +40,19 @@ func main() {
 		NoColor:    !colors,
 	})
 
+	githubTag := &latest.GithubTag{
+		Owner:      "juanfont",
+		Repository: "headscale",
+	}
+
+	if cli.Version != "dev" {
+		res, _ := latest.Check(githubTag, cli.Version)
+		if res.Outdated {
+			fmt.Printf("An updated version of Headscale has been found (%s vs. your current %s). Check it out https://github.com/juanfont/headscale/releases\n",
+				res.Current, cli.Version)
+		}
+	}
+
 	err := cli.LoadConfig("")
 	if err != nil {
 		log.Fatal().Err(err)