A simple script to check if MySQL replication is working normally.

check_replication.rb

#!/usr/bin/ruby

password = `cat /root/mysql_root_password`
password.strip!
result = `mysql -u root -p#{password} -E -e "show slave status"`

values = {}
result.split(/\n/).each do |line|
  if md = line.match(/:/)
    key = md.pre_match.strip.to_sym
    value = md.post_match.strip
    values[key] = value
  end
end

message = ''
if values[:Slave_IO_Running] != 'Yes'
  message << "Slave_IO_Running: #{values[:Slave_IO_Running]}\n"
end

if values[:Slave_SQL_Running] != 'Yes'
  message << "Slave_SQL_Running: #{values[:Slave_SQL_Running]}\n"
end

if values[:Last_Errno] != '0'
  message << "Last_Errno: #{values[:Last_Errno]}\n"
end

if values[:Seconds_Behind_Master].to_i > 60
  message << "Seconds_Behind_Master: #{values[:Seconds_Behind_Master]}\n"
end

if message != ''
  system "echo #{message} | mailx -s 'Replication Alert' admin@example.com"
end