(raspberry pi) broadcast ip addresses after boot

broadcast_ip.rb

#!/usr/bin/env ruby
# encoding: utf-8

require 'socket'

hostname = Socket.gethostname
  
socket = UDPSocket.new
socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST, true)

10.times.each do
  ip_addresses = Socket.ip_address_list.map(&:ip_address).join(', ')

  socket.send("#{hostname}: #{ip_addresses}", 0, "255.255.255.255", 4223)
  sleep 10
end
 
socket.close

exit 0

broadcast_ip.service

# /etc/systemd/system/broadcast_ip.service
[Unit]
Description=Broadcast ip addresses
Requires=network-online.target

[Service]
ExecStart=/usr/local/bin/broadcast_ip.rb
KillMode=process
RemainAfterExit=no

[Install]
WantedBy=multi-user.target