Add iso builder

This adds a new package for the iso builder run directly on go.
This is extracted from the original elemental-cli and then from the now
build-less kairos-agent

This uses no deps on elemental, only deps are on kairos-agent for the
config stuff mainly.

Signed-off-by: Itxaka <itxaka.garcia@spectrocloud.com>

tools-image/enki/cmd/root.go

@@ -0,0 +1,90 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+func NewRootCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "enki",
+		Short: "enki",
+	}
+	cmd.PersistentFlags().Bool("debug", false, "Enable debug output")
+	cmd.PersistentFlags().String("config-dir", "/etc/elemental", "Set config dir (default is /etc/elemental)")
+	cmd.PersistentFlags().String("logfile", "", "Set logfile")
+	cmd.PersistentFlags().Bool("quiet", false, "Do not output to stdout")
+	_ = viper.BindPFlag("debug", cmd.PersistentFlags().Lookup("debug"))
+	_ = viper.BindPFlag("config-dir", cmd.PersistentFlags().Lookup("config-dir"))
+	_ = viper.BindPFlag("logfile", cmd.PersistentFlags().Lookup("logfile"))
+	_ = viper.BindPFlag("quiet", cmd.PersistentFlags().Lookup("quiet"))
+
+	if viper.GetBool("debug") {
+		logrus.SetLevel(logrus.DebugLevel)
+	}
+	return cmd
+}
+
+// rootCmd represents the base command when called without any subcommands
+var rootCmd = NewRootCmd()
+
+// Execute adds all child commands to the root command and sets flags appropriately.
+// This is called by main.main(). It only needs to happen once to the rootCmd.
+func Execute() {
+
+	err := rootCmd.Execute()
+	if err != nil {
+		os.Exit(1)
+	}
+}
+
+// CheckRoot is a helper to return on PreRunE, so we can add it to commands that require root
+func CheckRoot() error {
+	if os.Geteuid() != 0 {
+		return errors.New("this command requires root privileges")
+	}
+	return nil
+}
+
+type enum struct {
+	Allowed []string
+	Value   string
+}
+
+func (a enum) String() string {
+	return a.Value
+}
+
+func (a *enum) Set(p string) error {
+	isIncluded := func(opts []string, val string) bool {
+		for _, opt := range opts {
+			if val == opt {
+				return true
+			}
+		}
+		return false
+	}
+	if !isIncluded(a.Allowed, p) {
+		return fmt.Errorf("%s is not included in %s", p, strings.Join(a.Allowed, ","))
+	}
+	a.Value = p
+	return nil
+}
+
+func (a *enum) Type() string {
+	return "string"
+}
+
+// newEnum give a list of allowed flag parameters, where the second argument is the default
+func newEnumFlag(allowed []string, d string) *enum {
+	return &enum{
+		Allowed: allowed,
+		Value:   d,
+	}
+}