Don't assume /bin/sh is there in the base image

In other words, don't run `RUN` commands that might not be there.
Ideally all `RUN` commands should run on the builder stage and at the
final step, we just copy everything over.

Signed-off-by: Dimitris Karakasilis <dimitris@karakasilis.me>

tools-image/enki/cmd/convert.go

@@ -10,12 +10,12 @@ import (
 // the root command.
 func NewConvertCmd() *cobra.Command {
 	c := &cobra.Command{
-		Use:   "convert rootfs",
+		Use:   "convert /path/to/rootfs /path/to/result image_name",
 		Short: "Convert a base image to a Kairos image",
 		Long: "Convert a base image to a Kairos image\n\n" +
 			"This is best effort. Enki will try to detect the distribution and add\n" +
 			"the necessary bits to convert it to a Kairos image",
-		Args: cobra.ExactArgs(2),
+		Args: cobra.ExactArgs(3),
 		PreRunE: func(cmd *cobra.Command, args []string) error {
 			return CheckRoot() // TODO: Do we need root?
 		},

tools-image/enki/pkg/action/converter.go

@@ -84,13 +84,18 @@ func (ca *ConverterAction) createDockerfile() (string, error) {
 
 	// write data to the temporary file
 	data := []byte(`
+FROM busybox as builder
+RUN mkdir /rootfs
+COPY . /rootfs/.
+
+RUN echo "nameserver 8.8.8.8" > /rootfs/etc/resolv.conf
+RUN cat /rootfs/etc/resolv.conf
+
 FROM scratch as rootfs
-COPY . .
 
-FROM rootfs
+COPY --from=builder /rootfs/ .
 
-RUN echo "nameserver 8.8.8.8" > /etc/resolv.conf
-RUN cat /etc/resolv.conf
+FROM rootfs
 
 # TODO: Do more clever things
 RUN apt-get update && apt-get install -y curl
@@ -136,6 +141,7 @@ func (ca *ConverterAction) removeDockerIgnore() error {
 func (ca *ConverterAction) BuildWithKaniko(dockerfile, resultPath string) (string, error) {
 	d, err := ca.Runner.Run(
 		"executor",
+		//"--verbosity", "debug",
 		"--dockerfile", dockerfile,
 		"--context", ca.rootFSPath,
 		"--destination", ca.imageName, // This is the name of the image when you: cat image.tar | docker load