Add new condition for when not removing any backups

Add a check for when retention equals 0. When retentions is set to 0 but no backups exist the message would still say "No old backups to remove for $vm".

This change changes the message as no backups would be removed even if they were found.

lxc-backup.sh

@@ -1,102 +1,97 @@
 #!/usr/bin/env bash
 
 main() {
-  while getopts ":l:d:t:c:h" opt; do
+  # Set default options
+  local cmd="${CMD:-lxc}"
+  local backup_dir="${BACKUP_DIR:-$PWD}"
+  local compression="${COMPRESSION:-zstd}"
+  local vm_list
+  local retention=0
+
+  while getopts ":l:d:t:x:c:h" opt; do
     case "${opt}" in
       l)
-        unset VM_FILTER
-        IFS="," read -r -a VM_FILTER <<< "$OPTARG"
-        ;;
+        IFS="," read -r -a vm_list <<< "$OPTARG";;
       d)
-        local backup_location="${OPTARG}"
-        backup_location="${backup_location%/}"
-        ;;
+        backup_dir="${OPTARG%/}";;
       t)
-        declare -g TARGET="$OPTARG"
-        ;;
+        cmd="$OPTARG";;
+      x)
+        compression="$OPTARG";;
       c)
-        declare -g run_cleanup=y
-        declare -g files_to_keep="${OPTARG}"
-        ;;
-      h)
-        usage
-        ;;
-      *)
-        usage
-        ;;
+        retention="${OPTARG}";;
+      h|*)
+        usage;;
     esac
   done
 
-  backup_location=${backup_location:-$PWD}
+  lxc() { command "$cmd" "$@"; }
+  list_vms() { lxc list -c n -f csv; }
 
-  if [[ "${#VM_FILTER[*]}" -gt 0 ]]; then
-    backup_vms "$backup_location" "${VM_FILTER[@]}"
-  else
-    backup_vms "$backup_location"
+  if ((${#vm_list[@]} == 0)); then
+    mapfile -t vm_list < <(list_vms)
   fi
-}
 
-lxc() {
-	local lxc_cmd="${TARGET:-lxc}"
-	command "$lxc_cmd" "$@"
-}
+  for vm in "${vm_list[@]}"; do
+    start_backup "$vm" "$backup_dir" "$compression"
 
-list_vms() {
-	lxc list -c n -f csv
+    if (( retention > 0 )); then
+      prune_backups "$vm" "$backup_dir" "$retention"
+    fi
+  done
+
+  exit 0
 }
 
 usage() {
   cat <<EOF
-Usage: ${0##*/} [-l vm[,vm...]] [-d backup_dir] [-t lxc|incus] [-c <keep n backups>] [-h]
+Usage: ${0##*/} [-l vm[,vm...]] [-d <backup directory>] [-t lxc|incus] [-x <compression alogorithm>] [-c <keep last n backups>] [-h]
 
 Options:
   -l  Comma-separated list of VMs to back up
   -d  Directory where backups will be stored (default: current directory)
   -t  Manager type: lxc or incus (default: lxc)
-  -c  Cleanup old backups keeping a set number (default: 2)
+  -x  Compression algorithm (e.g. gzip, zstd, none)
+  -c  Cleanup old backups and keep last <n> (default: keep all)
   -h  Show this message
-
 EOF
   exit 1
 }
 
-backup_vms() {
-  local backup_location="$1"; shift
-  local vms=("$@")
-
-  # when no argument use list of all VMs
-  if ((${#vms[@]} == 0)); then
-    mapfile -t vms < <(list_vms)
-  fi
-
-  for vm in "${vms[@]}"; do
-    [[ -n $vm ]] || continue
-    start_backup "$vm" "$backup_location"
-  done
-}
-
 start_backup() {
   local vm=$1
-  local backup_base="$2"
-  local destination="${backup_base}/${vm}"
-  local backup_name="${vm}_$(date +"%Y-%m-%d_%H-%M-%S").tar"
+  local backup_dir="$2"
+  local compression="$3"
+  local ext=".${compression}"
 
-  [[ -d "$backup_base" ]] || { echo "${backup_base} is not a directory"; exit 1; }
-  [[ -d "$destination" ]] || mkdir "$destination"
-  [[ -f "${destination}/${backup_name}" ]] && { echo "Backup already exists"; return 2; }
+  if [[ "$compression" == 'none' ]]; then
+    ext=""
+  else
+    command -v "$compression" >/dev/null 2>&1 || { echo "$compression command not found"; exit 1; }
+  fi
 
-  lxc export "$vm" --instance-only --compression none "${destination}/${backup_name}" || { echo "Error exporting $vm"; return 1; }
+  local vm_dir="${backup_dir}/${vm}"
+  local backup_name
+  backup_name="${vm}_$(date +"%Y-%m-%d_%H-%M-%S").tar${ext}"
 
-  [[ -n "$run_cleanup" ]] && prune_backups "$destination"
+  [[ -d "$backup_dir" ]] || { echo "${backup_dir} is not a directory"; exit 1; }
+  [[ -d "$vm_dir" ]] || mkdir "$vm_dir" || { echo "Cannont create $vm_dir"; exit 1; }
+  [[ -f "${vm_dir}/${backup_name}" ]] && { echo "Backup already exists"; return 2; }
+  echo "starting $vm"
+  lxc export "$vm" --instance-only --compression "${compression}" "${vm_dir}/${backup_name}" || { echo "Error exporting $vm"; return 1; }
 }
 
 prune_backups() {
-  local backup_directory="$1"
-  mapfile -t backup_files < <(find "$backup_directory" -maxdepth 1 -name "*.tar" -printf '%T@ %p\n' | sort -n | head -n "-${files_to_keep}" | cut -d' ' -f2-)
+  local vm="$1"
+  local backup_dir="$2"
+  local retention="$3"
+  mapfile -t backup_files < <(find "${backup_dir}/${vm}" -maxdepth 1 -type f -printf '%T@ %p\n' | sort -n | head -n "-${retention}" | cut -d' ' -f2-)
 
   if [[ ${#backup_files[@]} -gt 0 ]]; then
-    echo "Removing ${#qcow2_files[@]} old backup files for $vm (keeping last $total_files_to_keep files)"
-    printf '%s\0' "${backup_files[@]}" | xargs -0 rm -fv
+    echo "Removing ${#backup_files[@]} old backup files for $vm (keeping last $retention files)"
+    printf '%s\0' "${backup_files[@]}" | xargs -0 rm -fv > /dev/null
+  elif [[ "${retention}" -eq 0 ]]; then
+    echo "Keeping all existing backups for $vm"
   else
     echo "No old backups to remove for $vm"
   fi