Add self-contained automated server upgrade package

install.sh

@@ -5,8 +5,17 @@ umask 077
 ROOT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
 [[ $EUID == 0 ]] || { echo 'Use sudo ./install.sh [--enable-timer]' >&2; exit 1; }
 ENABLE_TIMER=false
-case ${1:-} in --enable-timer) ENABLE_TIMER=true ;; '') ;; *) echo 'Usage: sudo ./install.sh [--enable-timer]' >&2; exit 1 ;; esac
-(( $# <= 1 )) || exit 1
+NO_TIMER=false
+SNAPSHOT_DIR=''
+while (( $# )); do
+  case $1 in
+    --enable-timer) ENABLE_TIMER=true; shift ;;
+    --no-timer) NO_TIMER=true; shift ;;
+    --snapshot-dir) SNAPSHOT_DIR=${2:?Missing snapshot directory}; shift 2 ;;
+    *) echo 'Usage: sudo ./install.sh [--enable-timer | --no-timer] [--snapshot-dir DIR]' >&2; exit 1 ;;
+  esac
+done
+[[ $NO_TIMER != true || $ENABLE_TIMER != true ]] || exit 1
 # Syntax and packaging errors must be caught BEFORE changing the running installation.
 for file in "$ROOT_DIR"/usr-local-sbin/*.sh "$ROOT_DIR/lib/common.sh"; do bash -n "$file"; done
 python3 - "$ROOT_DIR/lib/backup_set.py" <<'PY'
@@ -21,22 +30,27 @@ if [[ -f /etc/app-backup/app-backup.conf ]]; then
   # shellcheck disable=SC1091
   source /etc/app-backup/app-backup.conf
 fi
-[[ ! -L $LOCKFILE ]] || exit 1
-exec 9>"$LOCKFILE"
-flock -n 9 || { echo 'Backup/restore is running. Retry after it finishes.' >&2; exit 1; }
+# shellcheck source=lib/locking.sh
+source "$ROOT_DIR/lib/locking.sh"
+acquire_backup_lock
 if systemctl is-active --quiet app-backup.service; then
   echo 'app-backup.service is active. Wait for completion before updating.' >&2
   exit 1
 fi
 TIMER_ACTIVE=false
 if systemctl is-active --quiet app-backup.timer; then TIMER_ACTIVE=true; fi
-SNAPSHOT=$(mktemp -d /var/backups/app-backup-update-XXXXXXXX)
+if [[ -n $SNAPSHOT_DIR ]]; then
+  [[ $SNAPSHOT_DIR == /* && ! -e $SNAPSHOT_DIR ]] || { echo 'Snapshot directory must be new and absolute'; exit 1; }
+  mkdir -m 700 -- "$SNAPSHOT_DIR"
+  SNAPSHOT=$SNAPSHOT_DIR
+else SNAPSHOT=$(mktemp -d /var/backups/app-backup-update-XXXXXXXX); fi
 chmod 700 "$SNAPSHOT"
 declare -a SOURCES TARGETS MODES
 add() { SOURCES+=("$ROOT_DIR/$1"); TARGETS+=("$2"); MODES+=("$3"); }
 add usr-local-sbin/app-backup.sh /usr/local/sbin/app-backup.sh 750
 add usr-local-sbin/app-restore.sh /usr/local/sbin/app-restore.sh 750
 add lib/common.sh /usr/local/lib/app-backup/common.sh 640
+add lib/locking.sh /usr/local/lib/app-backup/locking.sh 640
 add lib/backup_set.py /usr/local/lib/app-backup/backup_set.py 640
 add systemd/app-backup.service /etc/systemd/system/app-backup.service 644
 # Preserve existing schedules. The new timer template remains available as .dist.
@@ -50,6 +64,7 @@ else add etc/app-backup/app-backup.conf /etc/app-backup/app-backup.conf 600; fi
 for f in "$ROOT_DIR"/etc/app-backup/*.example; do add "etc/app-backup/$(basename "$f")" "/etc/app-backup/$(basename "$f")" 600; done
 add README.md /usr/local/share/doc/app-backup/README.md 644
 add Dokumentation.md /usr/local/share/doc/app-backup/Dokumentation.md 644
+add UPDATE_ANLEITUNG.md /usr/local/share/doc/app-backup/UPDATE_ANLEITUNG.md 644
 # Save the exact replaced files plus a rollback inventory; do not dereference links.
 : > "$SNAPSHOT/present.txt"; : > "$SNAPSHOT/absent.txt"
 for i in "${!TARGETS[@]}"; do
@@ -69,8 +84,9 @@ set -euo pipefail
 here=$(cd -- "$(dirname -- "$0")" && pwd)
 LOCKFILE=/run/app-backup.lock
 if [[ -f /etc/app-backup/app-backup.conf ]]; then source /etc/app-backup/app-backup.conf; fi
-exec 9>"$LOCKFILE"
-flock -n 9 || { echo 'Backup/restore/update is running'; exit 1; }
+# shellcheck disable=SC1091
+source "$here/locking.sh"
+acquire_backup_lock
 if systemctl is-active --quiet app-backup.service; then echo 'Backup service is active'; exit 1; fi
 systemctl stop app-backup.timer
 while IFS= read -r target; do cp -a --remove-destination -- "$here$target" "$target"; done < "$here/present.txt"
@@ -78,6 +94,8 @@ while IFS= read -r target; do rm -f -- "$target"; done < "$here/absent.txt"
 systemctl daemon-reload
 echo 'Previous package restored; config and timer state require manual review. Timer remains stopped.'
 ROLLBACK
+cp -- "$ROOT_DIR/lib/locking.sh" "$SNAPSHOT/locking.sh"
+chmod 600 "$SNAPSHOT/locking.sh"
 chmod 700 "$SNAPSHOT/rollback.sh"
 CHANGING=false
 on_exit() {
@@ -104,8 +122,9 @@ install -d -m 700 /var/log/app-backup /var/backups/app-backup
 systemctl daemon-reload
 # A persistent timer can fire immediately. Release the package lock only after
 # all files are installed, but before that timer can start the new backup.
-flock -u 9
-if [[ $ENABLE_TIMER == true ]]; then systemctl enable --now app-backup.timer
+if [[ ${APP_BACKUP_INHERIT_LOCK:-0} != 1 ]]; then flock -u 9; fi
+if [[ $NO_TIMER == true ]]; then :
+elif [[ $ENABLE_TIMER == true ]]; then systemctl enable --now app-backup.timer
 elif [[ $TIMER_ACTIVE == true ]]; then systemctl start app-backup.timer; fi
 CHANGING=false
 echo "Installed. Rollback package: $SNAPSHOT"