orange flavor can now use either snapper or pure btrfs snapshotter,

need to fix test-cli and more checks for error handling.
install, reset and upgrade is tested and working on green/orange

Changelog:
- reintroduced state directories variables, it makes code simpler,
- changed grub configuration. It should allow downgrades,
- snapper configuration is now created using a chroot in the snapshot,
- snapper initial snapshot bootstrap has changed (rely on snapper chroot initial snapshot creation),
- removed snapper xml code (handled by snapper itself),
- fixed old snapshot deletion,
- added snapper wrappers to run inside chroot or in current context,
- default btrfs subvolume is always updated

examples/orange/Dockerfile

@@ -62,10 +62,8 @@ ARG KBD=2.6.4
 RUN curl -L https://mirrors.edge.kernel.org/pub/linux/utils/kbd/kbd-${KBD}.tar.xz --output kbd-${KBD}.tar.xz && \
     tar xaf kbd-${KBD}.tar.xz && mkdir -p /usr/share/keymaps && cp -Rp kbd-${KBD}/data/keymaps/* /usr/share/keymaps/
 
-# Symlink grub2-editenv and snapper global config
-RUN mkdir -p /etc/sysconfig && \
-    ln -sf //etc/default/snapper /etc/sysconfig/snapper && \
-    ln -sf /usr/bin/grub-editenv /usr/bin/grub2-editenv
+# Symlink grub2-editenv
+RUN ln -sf /usr/bin/grub-editenv /usr/bin/grub2-editenv
 
 # Just add the elemental cli
 COPY --from=toolkit /usr/bin/elemental /usr/bin/elemental

pkg/features/embedded/grub-config/etc/elemental/grub.cfg

@@ -72,17 +72,19 @@ function source_bootargs {
 ## Defines the volume and image to boot from for active or passive boots
 function set_volume {
   if [ "${snapshotter}" == "btrfs" ]; then
+    # apply btrfs default subvolume if applicable
+    set btrfs_relative_path="y"
+    set volume="${root}"
+    # check if active snap is defined with default top level volume
     if [ -d "@/.snapshots/${active_snap}/snapshot" ]; then
-      set volume="${root}"
       if [ -n "${1}" ]; then
         set img="@/.snapshots/${1}/snapshot"
       else
         set img="@/.snapshots/${active_snap}/snapshot"
       fi
       set root_subpath="${img}/"
     else
-      set btrfs_relative_path="y"
-      set volume="${root}"
+      # if not in top level use subvolume based mounts 
       set root_subpath=""
       if [ -n "${1}" ]; then
         set img="@/.snapshots/${1}/snapshot"