check-redis-slave-status.rb

#!/usr/bin/env ruby
#
# Checks Redis Slave Replication

require 'rubygems' if RUBY_VERSION < '1.9.0'
require 'sensu-plugin/check/cli'
require 'redis'

class RedisSlaveCheck < Sensu::Plugin::Check::CLI

  option :host,
    :short => "-h HOST",
    :long => "--host HOST",
    :description => "Redis Host to connect to",
    :required => false,
    :default => '127.0.0.1'

  option :port,
    :short => "-p PORT",
    :long => "--port PORT",
    :description => "Redis Port to connect to",
    :proc => proc { |p| p.to_i },
    :required => false,
    :default => 6379

  option :password,
    :short => "-P PASSWORD",
    :long => "--password PASSWORD",
    :description => "Redis Password to connect with"

  def run
    begin

      options = {:host => config[:host], :port => config[:port]}
      options[:password] = config[:password] if config[:password]
      redis = Redis.new(options)

      if redis.info.fetch('master_link_status') == 'up'
        ok 'The redis master links status is up!'
      else
        msg = ''
        msg += "The redis master link status to: #{redis.info.fetch('master_host')} is down!"
        msg += " It has been down for #{redis.info.fetch('master_link_down_since_seconds')}."
        critical msg
      end

    rescue KeyError
      critical "Redis server on #{config[:host]}:#{config[:port]} is master"

    rescue
      critical "Could not connect to Redis server on #{config[:host]}:#{config[:port]}"
    end
  end
end