feat: Add btrfs-assistant to easily configure automatic snapshots of /home (#1459)

* feat: include btrfs-assistant and include a default config-template
We are providing a default config meant to be used with `sudo snapper create-config /var/home` so it will work with the automatic snapper systemd units that btrfs-assistant configures.

snapshotting / is pretty pointless on ostree so the root config points to /var/home instead.

* fix: launch btrfs-assistant in xwayland to avoid a bug with xdg-document-portal

* feat: add snapper-setup script
does not touch anything if user has already configured snapper

* fix: patch btrfs-assistant-launcher to not pass XDG_RUNTIME_DIR
This will make it run in xwayland instead

* chore: set sane defaults for snapshotting $HOME

Containerfile

@@ -421,6 +421,7 @@ RUN --mount=type=cache,dst=/var/cache/rpm-ostree \
         ydotool \
         yafti \
         stress-ng \
+        btrfs-assistant \
         lsb_release && \
     rpm-ostree install \
         ublue-update && \
@@ -430,6 +431,7 @@ RUN --mount=type=cache,dst=/var/cache/rpm-ostree \
     sed -i 's/max_cpu_load_percent.*/max_cpu_load_percent = 100.0/' /etc/ublue-update/ublue-update.toml && \
     sed -i 's/max_mem_percent.*/max_mem_percent = 90.0/' /etc/ublue-update/ublue-update.toml && \
     sed -i 's/dbus_notify.*/dbus_notify = false/' /etc/ublue-update/ublue-update.toml && \
+    sed -i 's/ --xdg-runtime=\\"${XDG_RUNTIME_DIR}\\"//g' /usr/bin/btrfs-assistant-launcher && \
     curl -Lo /usr/bin/installcab https://raw.githubusercontent.com/KyleGospo/steam-proton-mf-wmv/master/installcab.py && \
     chmod +x /usr/bin/installcab && \
     curl -Lo /usr/bin/install-mf-wmv https://github.com/KyleGospo/steam-proton-mf-wmv/blob/master/install-mf-wmv.sh && \
@@ -720,6 +722,7 @@ RUN rm -f /etc/profile.d/toolbox.sh && \
     systemctl enable bazzite-hardware-setup.service && \
     systemctl disable tailscaled.service && \
     systemctl enable dev-hugepages1G.mount && \
+    systemctl enable bazzite-snapper-setup && \
     systemctl --global enable bazzite-user-setup.service && \
     systemctl --global enable podman.socket && \
     systemctl --global enable systemd-tmpfiles-setup.service && \

system_files/desktop/shared/usr/lib/systemd/system/bazzite-snapper-setup.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=Create a default snapper config if snapper is unconfigured
+After=local-fs.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/libexec/bazzite-snapper-setup
+
+[Install]
+WantedBy=multi-user.target

system_files/desktop/shared/usr/libexec/bazzite-snapper-setup

@@ -0,0 +1,4 @@
+#!/bin/bash
+if ! snapper get-config >/dev/null 2>&1; then
+    snapper create-config /var/home
+fi

system_files/desktop/shared/usr/share/snapper/config-templates/default

@@ -0,0 +1,63 @@
+# subvolume to snapshot
+# With ostree it is pointless to snapshot /,
+# so we set the root config to snapshot /var/home instead
+SUBVOLUME="/var/home"
+
+# filesystem type
+FSTYPE="btrfs"
+
+
+# btrfs qgroup for space aware cleanup algorithms
+QGROUP=""
+
+
+# fraction or absolute size of the filesystems space the snapshots may use
+SPACE_LIMIT="0.5"
+
+# fraction or absolute size of the filesystems space that should be free
+FREE_LIMIT="0.2"
+
+
+# users and groups allowed to work with config
+ALLOW_USERS=""
+ALLOW_GROUPS=""
+
+# sync users and groups from ALLOW_USERS and ALLOW_GROUPS to .snapshots
+# directory
+SYNC_ACL="no"
+
+
+# start comparing pre- and post-snapshot in background after creating
+# post-snapshot
+BACKGROUND_COMPARISON="yes"
+
+
+# run daily number cleanup
+NUMBER_CLEANUP="yes"
+
+# limit for number cleanup
+NUMBER_MIN_AGE="1800"
+NUMBER_LIMIT="50"
+NUMBER_LIMIT_IMPORTANT="10"
+
+
+# create hourly snapshots
+TIMELINE_CREATE="yes"
+
+# cleanup hourly snapshots after some time
+TIMELINE_CLEANUP="yes"
+
+# limits for timeline cleanup
+TIMELINE_MIN_AGE="1800"
+TIMELINE_LIMIT_HOURLY="8"
+TIMELINE_LIMIT_DAILY="4"
+TIMELINE_LIMIT_WEEKLY="4"
+TIMELINE_LIMIT_MONTHLY="3"
+TIMELINE_LIMIT_YEARLY="0"
+
+
+# cleanup empty pre-post-pairs
+EMPTY_PRE_POST_CLEANUP="yes"
+
+# limits for empty pre-post-pair cleanup
+EMPTY_PRE_POST_MIN_AGE="90"