A Keepalived script

keepalived-notifier.rb

#!/usr/bin/ruby

# This is in my keepalived.conf
#  ... 
#  notify_master "/usr/tools/keepalived/notify.sh primary"
#  notify_backup "/usr/tools/keepalived/notify.sh backup"
#  notify_fault  "/usr/tools/keepalived/notify.sh fault"
#  ...

require 'socket'
require 'logger'
require 'thread'
include Socket::Constants

pid = fork do
	SCRIPTS = %w[radvd.sh conntrack.sh dhcp.sh routes.sh]
	$workdir = '/usr/tools/keepalived'

	LOG = Logger.new("/var/log/keepalived-notifier.log", 2, 1024*1024) # rotate after 1MB and keep 2 copies
	LOG.level = Logger::INFO
	LOG.datetime_format = '%Y-%m-%d %H:%M:%S'
	LOG.info "Application started!"
	
	mutex = Mutex.new
	action = 0
	act = 0
	state_back = 0
	state_prim = 0
	
	time_start = Time.now.to_i
	time_now = Time.now.to_i
	
	Thread.start do
		loop do
			sleep 1800
			mutex.synchronize do
				LOG.info "stats: primary: #{state_prim} backup: #{state_back}"
			end
		end
	end
	
	socket = UDPSocket.new
	socket.bind(nil, 503)
	loop do
		text, sender = socket.recvfrom(16384)
		len = text.length-1
		char = len == 0 ? text : text[len,len]
		
		if char == "1"
			LOG.info "Going primary"
			mutex.synchronize { state_prim += 1 }
			Dir.chdir $workdir do
					SCRIPTS.each do |s|
						next unless File.exist? s
						cmd = "./#{s} primary"
						LOG.info "  Executing '#{cmd}'"
						`#{cmd}`
						LOG.info "  Done executing '#{cmd}'"
					end
			end
			LOG.info "Done"
		elsif char == "2"
			LOG.info "Going backup"
			mutex.synchronize { state_back += 1 }
			Dir.chdir $workdir do
					SCRIPTS.each do |s|
						next unless File.exist? s
						cmd = "./#{s} backup"
						LOG.info "  Executing '#{cmd}'"
						`#{cmd}`
						LOG.info "  Done executing '#{cmd}'"
					end
			end
			LOG.info "Done"
		elsif char == "3"
			LOG.info "Going fault"
			mutex.synchronize { state_back += 1 }
			Dir.chdir $workdir do
					SCRIPTS.each do |s|
						next unless File.exist? s
						cmd = "./#{s} fault"
						LOG.info "  Executing '#{cmd}'"
						`#{cmd}`
						LOG.info "  Done executing '#{cmd}'"
					end
			end
			LOG.info "Done"
		else
			LOG.warn "Unknown action: #{char.gsub("\n",'\n')}"
		end
	end
end

# write pid
File.open("/var/run/keepalived-notifier.pid",'w') { |fh| fh.write pid }

# and detach
Process.detach pid

notify.sh

#!/bin/bash

if [ ! -e /var/run/keepalived-notifier.pid ]
then
	(cd /usr/tools/keepalived && ./keepalived-notifier.rb)
	sleep 2
fi


if [ -e /var/run/keepalived-notifier.pid ]
then
	case "$1" in
		primary)
			echo -n 1 | nc -u 127.0.0.1 503
			;;
		backup)
			echo -n 2 | nc -u 127.0.0.1 503
			;;
		fault)
			echo -n 3 | nc -u 127.0.0.1 503
			;;
		*)
			logger "ERROR: unknown state transition '$1'"
			exit 1
			;;
	esac
else
	logger "ERROR: file /var/run/keepalived-notifier.pid does not exist. Cannot notify..."
	exit 1
fi

exit 0