feat(uninstall): --skip-docker-images keeps the docker layer for fast reinstall

A full uninstall tears down the rootless daemon and removes the
docker-install user's home, which destroys the WebUI image AND the build
cache — so every reinstall's `docker build` runs from scratch (slow,
re-pulls the base image + reinstalls deps). On a slow local box that
dominates the iteration loop.

--skip-docker-images on `init.sh ... uninstall` preserves the rootless
docker layer: it still removes stale containers, the control plane,
manager user, footprint and /docker, but keeps the daemon running, the
docker-install user + home (image/layer cache), and the rootless sysctl
drop-in. The following reinstall then finds rootless already set up and
rebuilds the WebUI image from cache — fast. No effect on install.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>

init.sh

@@ -10,11 +10,17 @@
 #   --unattended        Run in unattended mode (skip confirmations)
 #   --skip-os-update    Skip operating system update
 #   --skip-prereqs      Skip installing prerequisite apps
+#   --skip-docker-images On UNINSTALL: keep the rootless docker daemon, the
+#                        docker-install user, and the image/build cache instead
+#                        of tearing them down — so a following reinstall rebuilds
+#                        the WebUI image from cache (fast) instead of from
+#                        scratch. (No effect on install.)
 #
 # Examples:
 #   ./init.sh --random-password --local init
 #   ./init.sh --random-password --local --unattended init
 #   ./init.sh --random-password --local --skip-os-update --skip-prereqs init
+#   ./init.sh --unattended --skip-docker-images uninstall   # keep docker layer
 #   ./init.sh init mypassword myuser mytoken https://github.com/user/repo.git
 #
 
@@ -90,6 +96,7 @@ init_local_install=false
 init_unattended_mode=false
 init_skip_os_update=false
 init_skip_prereqs=false
+init_skip_docker_images=false
 
 install_param="init"
 sudo_user_name=libreportal
@@ -144,6 +151,13 @@ for ((i=1; i<=$#; i++)); do
             init_skip_prereqs=true
             ((init_shift_count++))
             ;;
+        --skip-docker-images)
+            # On uninstall: preserve the rootless docker layer (daemon +
+            # docker-install user + image/build cache) so the next reinstall's
+            # `docker build` is cache-fast. Honored in runFullUninstall.
+            init_skip_docker_images=true
+            ((init_shift_count++))
+            ;;
     esac
 done
 
@@ -1305,6 +1319,13 @@ runFullUninstall()
 	iuser=$(grep -h '^CFG_DOCKER_INSTALL_USER=' /docker/configs/general/general_docker_install 2>/dev/null | head -1 | cut -d= -f2 | awk '{print $1}')
 	iuser="${iuser:-dockerinstall}"
 
+	# --skip-docker-images: keep the rootless docker layer (the daemon, the
+	# "$iuser" user, the image/build cache + the rootless sysctl drop-in) instead
+	# of tearing it down, so a following reinstall's `docker build` is cache-fast
+	# instead of from-scratch. Everything else (control plane, manager, footprint,
+	# /docker) is still removed.
+	local keep_docker="${init_skip_docker_images:-false}"
+
 	isHeader "LibrePortal — FULL Uninstall"
 	isError "This PERMANENTLY removes EVERYTHING — there is no undo:"
 	echo "    - all containers + images + the rootless docker setup"
@@ -1317,6 +1338,10 @@ runFullUninstall()
 	isNotice "LEFT IN PLACE: the docker engine, docker-compose, apt-installed deps,"
 	isNotice "and your SSH config (so you can't get locked out)."
 	echo ""
+	if [[ "$keep_docker" == "true" ]]; then
+		isNotice "--skip-docker-images: KEEPING the rootless docker daemon, the '$iuser' user, and the image/build cache (for a faster reinstall)."
+		echo ""
+	fi
 	if [[ "$init_unattended_mode" == true ]]; then
 		isNotice "Unattended mode — proceeding without the DELETE LIBREPORTAL prompt."
 	else
@@ -1340,23 +1365,35 @@ runFullUninstall()
 	#    user's session (stops the rootless dockerd + any survivors).
 	local uid; uid=$(id -u "$iuser" 2>/dev/null)
 	if [[ -n "$uid" ]]; then
+		# Remove stale containers either way — they bind-mount the about-to-be-
+		# wiped /docker. The images + build cache live in the user's home and are
+		# untouched by `docker rm`.
 		sudo -u "$iuser" env XDG_RUNTIME_DIR="/run/user/$uid" \
 			DOCKER_HOST="unix:///run/user/$uid/docker.sock" \
 			bash -c 'docker ps -aq | xargs -r docker rm -f' >/dev/null 2>&1 || true
-		sudo -u "$iuser" env XDG_RUNTIME_DIR="/run/user/$uid" \
+		if [[ "$keep_docker" == "true" ]]; then
-			dockerd-rootless-setuptool.sh uninstall >/dev/null 2>&1 || true
+			isSuccessful "Removed containers; kept the rootless docker daemon + images for '$iuser'"
-		loginctl disable-linger "$iuser" >/dev/null 2>&1 || true
+		else
-		loginctl terminate-user "$iuser" >/dev/null 2>&1 || true
+			sudo -u "$iuser" env XDG_RUNTIME_DIR="/run/user/$uid" \
-		pkill -9 -u "$iuser" >/dev/null 2>&1 || true
+				dockerd-rootless-setuptool.sh uninstall >/dev/null 2>&1 || true
-		isSuccessful "Stopped containers + rootless docker for '$iuser'"
+			loginctl disable-linger "$iuser" >/dev/null 2>&1 || true
+			loginctl terminate-user "$iuser" >/dev/null 2>&1 || true
+			pkill -9 -u "$iuser" >/dev/null 2>&1 || true
+			isSuccessful "Stopped containers + rootless docker for '$iuser'"
+		fi
 	fi
 
 	# 3. Remove the out-of-/docker footprint (see FOOTPRINT.md).
 	rm -f /usr/local/bin/libreportal
 	rm -rf /usr/local/lib/libreportal
 	rm -f "/etc/sudoers.d/$mgr"
-	rm -f /etc/sysctl.d/99-libreportal-hardening.conf /etc/sysctl.d/99-libreportal-rootless.conf
+	# Keep the sysctl drop-ins when preserving docker — removing + reloading them
-	sysctl --system >/dev/null 2>&1
+	# would reset ip_unprivileged_port_start etc. out from under the still-running
+	# rootless daemon. (The reinstall re-adds them idempotently.)
+	if [[ "$keep_docker" != "true" ]]; then
+		rm -f /etc/sysctl.d/99-libreportal-hardening.conf /etc/sysctl.d/99-libreportal-rootless.conf
+		sysctl --system >/dev/null 2>&1
+	fi
 	rm -f /usr/local/bin/restic /usr/local/bin/kopia /usr/local/bin/ufw-docker
 	rm -f /root/init.sh
 	isSuccessful "Removed the system-integration footprint"
@@ -1370,15 +1407,22 @@ runFullUninstall()
 	#    `userdel -r` leaves the home behind ("user currently used"); rm -rf the
 	#    home afterwards as a backstop.
 	local u
-	for u in "$mgr" "$iuser"; do
+	local users_to_remove=("$mgr")
+	[[ "$keep_docker" == "true" ]] || users_to_remove+=("$iuser")
+	for u in "${users_to_remove[@]}"; do
 		loginctl disable-linger "$u" >/dev/null 2>&1 || true
 		loginctl terminate-user "$u" >/dev/null 2>&1 || true
 		pkill -9 -u "$u" >/dev/null 2>&1 || true
 		userdel -r "$u" >/dev/null 2>&1 || true
 		[[ -n "$u" ]] && rm -rf "/home/$u"
 	done
-	sed -i "/^${mgr}:/d;/^${iuser}:/d" /etc/subuid /etc/subgid 2>/dev/null || true
+	if [[ "$keep_docker" == "true" ]]; then
-	isSuccessful "Removed users '$mgr' + '$iuser' (+ home dirs)"
+		sed -i "/^${mgr}:/d" /etc/subuid /etc/subgid 2>/dev/null || true
+		isSuccessful "Removed user '$mgr' (+ home); kept '$iuser' + its docker image store"
+	else
+		sed -i "/^${mgr}:/d;/^${iuser}:/d" /etc/subuid /etc/subgid 2>/dev/null || true
+		isSuccessful "Removed users '$mgr' + '$iuser' (+ home dirs)"
+	fi
 
 	isHeader "LibrePortal uninstalled"
 	isNotice "Left in place: docker engine, docker-compose, apt deps, SSH config."