Лаг по времени для встроенной репликации psql для nagios

nagios.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'pg'
require 'timeout'
require 'nagios-probe'

def master_connection_string
  {:user => 'nagios', :dbname => 'nagios', :host => 'master', :password => 'nagios'}
end

def slave_connection_string
  {:user => 'nagios', :dbname => 'nagios', :host => 'slave', :password => 'nagios'}
end

$stamp = Random.rand(100)

class ReplicationProbe< Nagios::Probe
  def check_crit
    conn = PG.connect( master_connection_string )
    conn.transaction do |conn|
      conn.exec("drop table if exists lag_table; create table lag_table (stamp integer); insert into lag_table VALUES( '#{$stamp}' );")
    end
    status = Timeout::timeout(60) {
      slave_stamp = -1
      sleep 1 #ERROR:  could not open relation with OID
      while (slave_stamp != $stamp)
        conn = PG.connect( slave_connection_string )
        conn.transaction do |conn|
          slave_stamp = conn.exec("select stamp from lag_table limit 1;").first["stamp"].to_i
        end
        sleep 1 #Timeout probe
      end
    }
  end

  def check_warn
    false
  end

  def crit_message
    "Lag is critical!"
  end

  def warn_message
    "nothing to message"
  end

  def ok_message
    "nothing to see here"
  end
end

begin
  options = { } 
  probe = ReplicationProbe.new(options)
  probe.run
rescue Exception => e
  puts "unknown: #{e}" 
  exit Nagios::UNKNOWN
end

puts probe.message
exit probe.retval