local delay=5
  while true; do
    "$@" && break
    if [[ $n -lt $max ]]; then
      ((n++))
      log "Command failed. Attempt $n/$max:"
      sleep $delay;
    else
      log "The command has failed after $n attempts."  >&2
      return 2
    fi
  done
}

# load_cluster_topology function reads cluster configuration topology file and
# sets up environment variables used by other functions. So this should be called