rootless must be root

cmd/dtk-ctk/rootless/main.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-
+        "os/user"
 	"github.com/urfave/cli/v2"
 )
 
@@ -32,6 +32,7 @@ func (m rootlessCommand) build() *cli.Command {
 	c := cli.Command{
 		Name:   "rootless",
 		Usage:  "Provide tools for configuring rootless container runtimes",
+		Before: func(ctx *cli.Context) error { return validateGenOptions(ctx) },
 		Action: func(ctx *cli.Context) error { return run(ctx, &opts) },
 	}
 
@@ -48,6 +49,15 @@ func (m rootlessCommand) build() *cli.Command {
 	return &c
 }
 
+func validateGenOptions(c *cli.Context) error {
+	curUser, err := user.Current()
+	if err != nil || curUser.Uid != "0" {
+		return fmt.Errorf("Permission denied: Not running as root")
+	}
+
+	return nil
+}
+
 func run(c *cli.Context, opts *options) error {
 	runtime := opts.runtime
 	if runtime != "docker" && runtime != "podman" {