Add orange btrfs support

- remove btrfs default subvolume,
- save btrfs device in Btrfs structure,
- rework brtfs state mountpoint detection (uses btrfs device, got rid of rootSubvolID and snapshotsSubvolID constants),
- add 'active' relative symlink to active snapshot (updated in CloseTransaction() and read in getActiveSnapshot()),
- add grub 'active_snap' variable (could it be replaced by dracut resolving the 'active' link ?),
- add grub 'root_subpath' variable which allows to prefix kernel and initrd image with a subpath,
- handle grub modules packaging under /usr/lib/elemental/bootloader
- add RelativizeLink() to recursively make symbolic links relative,
- ensure kernel and initrd are relative links (allow grub to process without mounting subvolume)
- update orange Dockerfile

examples/orange/Dockerfile

@@ -51,6 +51,9 @@ RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-ins
   locales \
   kbd \
   podman \
+  btrfs-progs \
+  btrfsmaintenance \
+  snapper \
   xz-utils
 
 # Hack to prevent systemd-firstboot failures while setting keymap, this is known
@@ -59,8 +62,10 @@ 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
-RUN ln -sf /usr/bin/grub-editenv /usr/bin/grub2-editenv
+# 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
 
 # Just add the elemental cli
 COPY --from=toolkit /usr/bin/elemental /usr/bin/elemental
@@ -75,8 +80,11 @@ RUN cp /usr/share/systemd/tmp.mount /etc/systemd/system
 # the default cloud-init
 RUN locale-gen --lang en_US.UTF-8
 
+# Add default snapshotter setup
+ADD snapshotter.yaml /etc/elemental/config.d/snapshotter.yaml
+
 # Generate initrd with required elemental services
-RUN elemental --debug init -f
+RUN elemental --debug init --force
 
 # Update os-release file with some metadata
 RUN echo IMAGE_REPO=\"${REPO}\"         >> /etc/os-release && \

examples/orange/snapshotter.yaml

@@ -0,0 +1,3 @@
+snapshotter:
+  type: btrfs
+  max-snaps: 4

pkg/action/init.go

@@ -74,6 +74,12 @@ func RunInit(cfg *types.RunConfig, spec *types.InitSpec) error {
 			cfg.Config.Logger.Errorf("failed creating kernel symlink")
 			return err
 		}
+
+		err = utils.RelativizeLink(cfg.Fs, constants.KernelPath)
+		if err != nil {
+			cfg.Config.Logger.Errorf("failed relativizing kernel symlink")
+			return err
+		}
 	}
 
 	cfg.Config.Logger.Info("Remove any pre-existing initrd")
@@ -89,7 +95,7 @@ func RunInit(cfg *types.RunConfig, spec *types.InitSpec) error {
 		cfg.Config.Logger.Errorf("dracut failed with output: %s", output)
 	}
 
-	cfg.Config.Logger.Debugf("darcut output: %s", output)
+	cfg.Config.Logger.Debugf("dracut output: %s", output)
 
 	initrd, err := utils.FindInitrd(cfg.Fs, "/")
 	if err != nil || !strings.HasPrefix(initrd, constants.ElementalInitrd) {
@@ -102,6 +108,12 @@ func RunInit(cfg *types.RunConfig, spec *types.InitSpec) error {
 	err = cfg.Fs.Symlink(initrd, constants.InitrdPath)
 	if err != nil {
 		cfg.Config.Logger.Errorf("failed creating initrd symlink")
+		return err
+	}
+
+	err = utils.RelativizeLink(cfg.Fs, constants.InitrdPath)
+	if err != nil {
+		cfg.Config.Logger.Errorf("failed relativizing initrd symlink")
 	}
 
 	return err

pkg/constants/constants.go

@@ -89,6 +89,7 @@ const (
 	GrubDefEntry           = "Elemental"
 	GrubFallback           = "default_fallback"
 	GrubPassiveSnapshots   = "passive_snaps"
+	GrubActiveSnapshot     = "active_snap"
 	ElementalBootloaderBin = "/usr/lib/elemental/bootloader"
 
 	// Mountpoints or links to images and partitions
@@ -270,6 +271,7 @@ func GetDefaultGrubModules() []string {
 
 func GetDefaultGrubModulesPatterns() []string {
 	return []string{
+		filepath.Join(ElementalBootloaderBin, "*-efi"),
 		"/boot/grub2/*-efi",
 		"/usr/share/grub*/*-efi",
 		"/usr/lib/grub*/*-efi",

pkg/features/embedded/elemental-sysroot/usr/lib/dracut/modules.d/20elemental-sysroot/sysroot-generator.sh

@@ -47,7 +47,12 @@ if [ "${snapshotter}" == "btrfs" ]; then
     rootvol_unit=$(systemd-escape -p --suffix=mount ${root_part_mnt})
     case "${elemental_mode}" in
         *active*)
-            opts="ro" ;;
+            if [ -z "${elemental_img}" ]; then
+                opts="ro"
+            else
+                opts="ro,subvol=${elemental_img}"
+            fi
+            ;;
         *passive*)
             opts="ro,subvol=${elemental_img}" ;;
         *)

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

@@ -65,30 +65,33 @@ function set_loopdevice {
 
 ## Sources bootargs from the current volume
 function source_bootargs {
-  source (${volume})/etc/cos/bootargs.cfg
-  source (${volume})/etc/elemental/bootargs.cfg
+  source (${volume})/${root_subpath}etc/cos/bootargs.cfg
+  source (${volume})/${root_subpath}etc/elemental/bootargs.cfg
 }
 
 ## Defines the volume and image to boot from for active or passive boots
 function set_volume {
   if [ "${snapshotter}" == "btrfs" ]; then
-    set btrfs_relative_path="y"
     set volume="${root}"
     if [ -n "${1}" ]; then
       set img="@/.snapshots/${1}/snapshot"
-      btrfs-mount-subvol ($root) / ${img}
+    else
+      set img="@/.snapshots/${active_snap}/snapshot"
     fi
+    set root_subpath="${img}/"
   elif [ -z "${1}" ]; then
+    set root_subpath=""
     set_loopdevice /.snapshots/active
   else
+    set root_subpath=""
     set img="/.snapshots/${1}/snapshot.img"
     set_loopdevice ${img}
   fi
 }
 
 menuentry "${display_name}" --id active {
   set mode=active
-  search --no-floppy --label --set=root ${state_label}
+  search --no-floppy --set root --label ${state_label}
   set_volume
   source_bootargs
   linux (${volume})${kernel} ${kernelcmd} ${extra_cmdline} ${extra_active_cmdline}
@@ -98,7 +101,7 @@ menuentry "${display_name}" --id active {
 for passive_snap in ${passive_snaps}; do
   menuentry "${display_name} (snapshot ${passive_snap})" --id passive${passive_snap} ${passive_snap} {
     set mode=passive
-    search --no-floppy --label --set=root ${state_label}
+    search --no-floppy --set root --label ${state_label}
     set_volume ${2}
     source_bootargs
     linux (${volume})${kernel} ${kernelcmd} ${extra_cmdline} ${extra_passive_cmdline}
@@ -108,7 +111,7 @@ done
 
 menuentry "${display_name} recovery" --id recovery {
   set mode=recovery
-  search --no-floppy --label --set=root ${recovery_label}
+  search --no-floppy --set root --label ${recovery_label}
 
   # Check the presence of the image and fallback to legacy path if not present
   set img=/boot/recovery.img

pkg/features/embedded/grub-default-bootargs/etc/elemental/bootargs.cfg

@@ -23,5 +23,5 @@ else
   set kernelcmd="console=tty1 console=ttyS0 root=LABEL=${state_label} ${img_arg} ${snap_arg} elemental.mode=${mode} elemental.oemlabel=${oem_label} panic=5 security=selinux fsck.mode=force fsck.repair=yes"
 fi
 
-set kernel=/boot/vmlinuz
-set initramfs=/boot/initrd
+set kernel=/${root_subpath}boot/vmlinuz
+set initramfs=/${root_subpath}boot/initrd