use backupKey from userData

setup/argparser.sh

@@ -16,6 +16,7 @@ arg_tls_key=""
 arg_token=""
 arg_version=""
 arg_web_server_origin=""
+arg_backup_key=""
 arg_aws=""
 
 args=$(getopt -o "" -l "data:,retire" -n "$0" -- "$@")
@@ -42,6 +43,9 @@ EOF
         arg_restore_key=$(echo "$2" | $json restoreKey)
         [[ "${arg_restore_key}" == "null" ]] && arg_restore_key=""
 
+        arg_backup_key=$(echo "$2" | $json backupKey)
+        [[ "${arg_backup_key}" == "null" ]] && arg_backup_key=""
+
         arg_aws=$(echo "$2" | $json aws)
         [[ "${arg_aws}" == "null" ]] && arg_aws=""