#!/usr/bin/env ruby
#
# MySQL Status Plugin
# ===
#
# This plugin attempts to login to mysql with provided credentials.
# NO DEPENDENCIES (no mysql-devel and thus no implicit mysql-server restart)
# It checks whether MySQL is UP --check status
# It checks replication delay --check replication
# Author: Magic Online - www.magic.fr
# Date: September 2016
#
# Author: Magic Online - www.magic.fr - September 2016
# Released under the same terms as Sensu (the MIT license); see LICENSE
# for details.
#
# USING INI ARGUMENT
# The ini file should be readable by the sensu user/group.
#
#   EXAMPLE
#     check-mysql-status.rb -h localhost --ini '/etc/sensu/my.cnf' --check status
#     check-mysql-status.rb -h localhost --ini '/etc/sensu/my.cnf' --check replication
#
#   MY.CNF INI FORMAT
#   [client]
#   user=sensu
#   password="abcd1234"
#   socket="/var/lib/mysql/mysql.sock"
#

require 'sensu-plugin/check/cli'
require 'inifile'
require 'open3'

# Check MySQL Status
class CheckMySQLStatus < Sensu::Plugin::Check::CLI
  option :user,
         description: 'MySQL User, you really should use ini to hide credentials instead of using me',
         short: '-u USER',
         long: '--user USER',
         default: 'mosim'

  option :password,
         description: 'MySQL Password, you really should use ini to hide credentials instead of using me',
         short: '-p PASS',
         long: '--password PASS',
         default: 'mysqlPassWord'

  option :ini,
         description: 'My.cnf ini file',
         short: '-i',
         long: '--ini VALUE'

  option :ini_section,
         description: 'Section in my.cnf ini file',
         long: '--ini-section VALUE',
         default: 'client'

  option :hostname,
         description: 'Hostname to login to',
         short: '-h HOST',
         long: '--hostname HOST',
         default: 'localhost'

  option :database,
         description: 'Database schema to connect to',
         short: '-d DATABASE',
         long: '--database DATABASE',
         default: 'test'

  option :port,
         description: 'Port to connect to',
         short: '-P PORT',
         long: '--port PORT',
         default: '3306'

  option :socket,
         description: 'Socket to use',
         short: '-s SOCKET',
         long: '--socket SOCKET',
         default: '/var/run/mysqld/mysqld.sock'

  option :binary,
         description: 'Absolute path to mysql binary',
         short: '-b BINARY',
         long: '--binary BINARY',
         default: 'mysql'

  option :check,
         description: 'type of check: (status|replication)',
         short: '-C CHECK',
         long: '--check CHECK',
         default: 'status'

  option :warn,
         description: 'Warning threshold for replication lag',
         short: '-w',
         long: '--warning=VALUE',
         default: 900

  option :crit,
         description: 'Critical threshold for replication lag',
         short: '-c',
         long: '--critical=VALUE',
         default: 1800

  option :debug,
         description: 'Print debug info',
         long: '--debug',
         default: false

  def credentials
    if config[:ini]
      ini = IniFile.load(config[:ini])
      section = ini[config[:ini_section]]
      db_user = section['user']
      db_pass = section['password']
      db_socket = if config[:socket]
                    config[:socket]
                  else
                    section['socket']
                  end
    else
      db_user = config[:user]
      db_pass = config[:password]
      db_socket = config[:socket]
    end
    [db_user, db_pass, db_socket]
  end

  # Status check
  def status_check(db_user, db_pass, db_socket)
    cmd = "#{config[:binary]} -u #{db_user} -h #{config[:hostname]} --port #{config[:port]} \
        --socket #{db_socket} -p\"#{db_pass.strip}\" --batch --disable-column-names -e 'show schemas;'"
    begin
      stdout, _stderr, status = Open3.capture3(cmd)
      if status.to_i == 0
        ok "#{status} | #{stdout.split("\n")}"
      else
        critical "Error message: status: #{status}"
      end
    rescue StandardError => e
      critical "Error message: status: #{status} | Exception: #{e}"
    ensure
      puts ''
    end
  end

  def replication_check(db_user, db_pass, db_socket)
    table = {}
    begin
      cmd = "#{config[:binary]} -u #{db_user} -h #{config[:hostname]} --port #{config[:port]} \
        --socket #{db_socket} -p\"#{db_pass.strip}\"  -e 'SHOW SLAVE STATUS\\G'"
      stdout, _stderr, status = Open3.capture3(cmd)
      if status.to_i != 0
        critical "Error message: status: #{status}"
      end
      stdout.split("\n").each do |line|
        key = line.split(':')[0]
        value = line.split(':')[1]
        table[key.strip.to_s] = value.to_s unless key.include? '***'
      end
      dict = []
      table.keys.to_a.each do |k|
        %w[Slave_IO_State Slave_IO_Running Slave_SQL_Running Last_IO_Error Last_SQL_Error Seconds_Behind_Master].each do |key|
          dict.push(k.strip.to_s) if key.strip == k.strip
        end
      end
      table.each do |attribute, value|
        puts "#{attribute} : #{value}" if config[:debug]
        warn "couldn't detect replication status :#{dict.size}" unless dict.size == 6
        slave_running = %w[Slave_IO_Running Slave_SQL_Running].all? do |key|
          table[key].to_s =~ /Yes/
        end
        output = 'Slave not running!'
        output += ' STATES:'
        output += " Slave_IO_Running=#{table['Slave_IO_Running']}"
        output += ", Slave_SQL_Running=#{table['Slave_SQL_Running']}"
        output += ", LAST ERROR: #{table['Last_SQL_Error']}"
        critical output unless slave_running
        replication_delay = table['Seconds_Behind_Master'].to_i
        message = "replication delayed by #{replication_delay}"
        if replication_delay > config[:warn].to_i && replication_delay <= config[:crit].to_i
          warning message
        elsif replication_delay >= config[:crit].to_i
          critical message
        else
          ok "slave running: #{slave_running}, #{message}"
        end
      end
      ok 'show slave status was nil. This server is not a slave.'
    rescue StandardError => e
      critical "Error message: status: #{status} | Exception: #{e}"
    end
  end

  def run
    db_user = credentials[0]
    db_pass = credentials[1]
    db_socket = credentials[2]
    if config[:check] == 'status'
      status_check(db_user, db_pass, db_socket)
    end
    if config[:check] == 'replication'
      replication_check(db_user, db_pass, db_socket)
    end
    unknown 'No check type succeeded. Check your options'
  end
end