Expand DeployImage to be more flexible (#635)

Usually we create the system dirs in images by default, but that means
that we cannot reuse the DeployImage for deploying random non-system
images.

This fixes it by adding an extra param to create the dir structure in
the created image

Signed-off-by: Itxaka <itxaka@kairos.io>

pkg/elemental/elemental.go

@@ -308,7 +308,23 @@ func (e Elemental) CreateFileSystemImage(img *v1.Image) error {
 
 // DeployImage will deploy the given image into the target. This method
 // creates the filesystem image file, mounts it and unmounts it as needed.
+// Creates the default system dirs by default (/sys,/proc,/dev, etc...)
 func (e *Elemental) DeployImage(img *v1.Image, leaveMounted bool) (info interface{}, err error) {
+	return e.deployImage(img, leaveMounted, true)
+}
+
+// DeployImageNodirs will deploy the given image into the target. This method
+// creates the filesystem image file, mounts it and unmounts it as needed.
+// Does not create the default system dirs so it can be used to create generic images from any source
+func (e *Elemental) DeployImageNodirs(img *v1.Image, leaveMounted bool) (info interface{}, err error) {
+	return e.deployImage(img, leaveMounted, false)
+}
+
+// deployImage is the real function that does the actual work
+// Set leaveMounted to leave the image mounted, otherwise it unmounts before returning
+// Set createDirStructure to create the directory structure in the target, which creates the expected dirs
+// for a running system. This is so we can reuse this method for creating random images, not only system ones
+func (e *Elemental) deployImage(img *v1.Image, leaveMounted, createDirStructure bool) (info interface{}, err error) {
 	target := img.MountPoint
 	if !img.Source.IsFile() {
 		if img.FS != cnst.SquashFs {
@@ -338,9 +354,11 @@ func (e *Elemental) DeployImage(img *v1.Image, leaveMounted bool) (info interfac
 		return nil, err
 	}
 	if !img.Source.IsFile() {
-		err = utils.CreateDirStructure(e.config.Fs, target)
-		if err != nil {
-			return nil, err
+		if createDirStructure {
+			err = utils.CreateDirStructure(e.config.Fs, target)
+			if err != nil {
+				return nil, err
+			}
 		}
 		if img.FS == cnst.SquashFs {
 			squashOptions := append(cnst.GetDefaultSquashfsOptions(), e.config.SquashFsCompressionConfig...)

pkg/utils/grub.go

@@ -46,6 +46,9 @@ func NewGrub(config *agentConfig.Config) *Grub {
 }
 
 // Install installs grub into the device, copy the config file and add any extra TTY to grub
+// TODO: Make it more generic to be able to call it from other places
+// i.e.: filepath.Join(cnst.ActiveDir, "etc/kairos-release") seraches for the file in the active dir, we should be looking into the rootdir?
+// filepath.Join(cnst.EfiDir, "EFI/boot/grub.cfg") we also write into the efi dir directly, this should be the a var maybe?
 func (g Grub) Install(target, rootDir, bootDir, grubConf, tty string, efi bool, stateLabel string) (err error) { // nolint:gocyclo
 	var grubargs []string
 	var grubdir, finalContent string