numerous updates

system/snapper.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+#
+# Purpose : Configure Snapper so update can snapshot / before each upgrade
+#           (updates.d/09-snapshot.sh). Only applies when / is btrfs, which is
+#           archinstall's default. /home is a separate subvolume and is not
+#           included in the snapshots.
+
+if [ "$(findmnt -no FSTYPE /)" != "btrfs" ]; then
+  echo "/ is not btrfs; skipping Snapper setup."
+  exit 0
+fi
+
+set -e
+
+source "$HOME/.local/share/coredesktop/utils.sh"
+
+install_packages snapper
+
+if [ ! -f /etc/snapper/configs/root ]; then
+  echo "Creating Snapper config for /..."
+
+  # create-config makes its own /.snapshots subvolume and fails if the path
+  # already exists. archinstall mounts a separate @.snapshots subvolume there,
+  # so follow the Arch wiki: unmount it, let snapper create its config, then
+  # swap snapper's nested subvolume back out for the @.snapshots mount.
+  if mountpoint -q /.snapshots; then
+    sudo umount /.snapshots
+    sudo rmdir /.snapshots
+    sudo snapper -c root create-config /
+    sudo btrfs subvolume delete /.snapshots
+    sudo mkdir /.snapshots
+    sudo mount /.snapshots
+  else
+    if [ -e /.snapshots ] && ! sudo rmdir /.snapshots 2>/dev/null; then
+      echo "/.snapshots exists and isn't an empty directory. Move it aside and run this again."
+      exit 1
+    fi
+    sudo snapper -c root create-config /
+  fi
+
+  # Keep only the last 5 pre-update snapshots, and no hourly timeline. Only set
+  # on a config we created, so a config you made yourself keeps its settings.
+  sudo snapper -c root set-config \
+    TIMELINE_CREATE=no \
+    NUMBER_CLEANUP=yes \
+    NUMBER_MIN_AGE=0 \
+    NUMBER_LIMIT=5 \
+    NUMBER_LIMIT_IMPORTANT=5
+  sudo systemctl disable --now snapper-timeline.timer 2> /dev/null || true
+else
+  echo "Snapper config for / already exists."
+fi
+
+sudo systemctl enable --now snapper-cleanup.timer