cmd: add a 'version' subcommand and flag to show the version

cmd/main.go

@@ -5,6 +5,8 @@ import (
 	"os"
 
 	"github.com/spf13/cobra"
+
+	"git.offline-twitter.com/offline-labs/gas-stack/pkg/version"
 )
 
 const (
@@ -16,12 +18,16 @@ const (
 func main() {
 	root_cmd := &cobra.Command{
 		Use:           "gas",
+		Version:       version.String(),
 		SilenceErrors: true,
 		SilenceUsage:  true,
 	}
+	// Print a bare version string ("v0.0.4"), rather than cobra's "gas version v0.0.4".
+	root_cmd.SetVersionTemplate("{{.Version}}\n")
 	root_cmd.AddCommand(sqlite_lint)
 	root_cmd.AddCommand(cmd_init)
 	root_cmd.AddCommand(generate_model)
+	root_cmd.AddCommand(cmd_version)
 	if err := root_cmd.Execute(); err != nil {
 		fmt.Println(RED + err.Error() + RESET)
 		os.Exit(1)