networkd-notify.rb

#!/usr/bin/env ruby
require "dbus"

system_bus = DBus::SystemBus.instance
session_bus = DBus::SessionBus.instance
$networkd_service = system_bus.service("org.freedesktop.network1")
$networkd_object = $networkd_service.object("/org/freedesktop/network1")
$networkd_properties = $networkd_object["org.freedesktop.DBus.Properties"]
$networkd_manager = $networkd_object["org.freedesktop.network1.Manager"]

def listen name, object
    $networkd_service.object(object)["org.freedesktop.DBus.Properties"].on_signal("PropertiesChanged") do |iface, props, inv_props|
        puts "Property change on #{name}: #{props}"
        notify name, props["OnlineState"] if props.include? "OnlineState"
    end
end

def notify name, state
    `notify-send "Link #{name} is #{state}"`
end

$networkd_properties.on_signal("PropertiesChanged") do |iface, props, inv_props|
    # Listen on the generic /network object 
    puts "Generic change for #{iface}: #{props}"
end

for index, name, object in $networkd_manager.ListLinks[0]
    listen name, object
end

main = DBus::Main.new
main << system_bus
main.run