mysqler.rb

=begin rdoc
  PoolParty plugin to install and configure mysql on any instance designated as a database instance.
  
  Written by Ron Evans (http://deadprogrammersociety.com)
  
  Features of the current plugin:
  - Installs current Mysql
  - Does live database backup to S3 once every hour
  - If the instance goes down, will automatically bring up another one, and restore latest backup
  
  Limitations of the current plugin:
  - Allows for one and only one database instance. 
  - The size of the database cannot exceed the amount of disk storage available to that instance size
  - Backups are going against the same production database, so performance may be impacted
=end
require 'poolparty'

class Mysqler < PoolParty::Plugin
  before_configure_cloud :upload_config_files
  after_configure_cloud :load_db_settings, :restore_database, :start_monit, :setup_backup
  
  attr_reader :db_settings
  
  define_custom_package :mysql do
    # Install mysql
    package :mysql, :provides => :database do
      description 'MySQL Database'
      apt %w( mysql-server mysql-client )
      
      requires :monit
    end

    # Install monit
    package :monit do 
      description 'Monit monitoring tool'
      apt 'monit'
    end
  end
  
  define_global_file "mysql-backup" do
    load_db_settings
    "00 * * * * /usr/bin/mysqldump -u #{@db_settings[:user]} -p#{@db_settings[:password]} -x --all-databases > /data/#{@db_settings[:backup_dir]}/db_dump.sql"
  end
  
  # uploads mysql and monit config files to server instance
  def upload_config_files(c)
    c.scp("#{File.dirname(File.expand_path(__FILE__))}/my.cnf", "/etc/my.cnf")
    c.scp("#{File.dirname(File.expand_path(__FILE__))}/mysqler.monit.conf", "/etc/monit.d/mysqler.monit.conf")
  end
  
  # load settings for plugin
  def load_db_settings(c=nil)
    @db_settings ||= read_config_file("#{PoolParty.user_dir}/config/mysql.yml")
  end
  
  # restore the mysql database from backups
  def restore_database(c)
    c.ssh "mysql -u #{@db_settings[:user]} -p#{@db_settings[:password]} < /data/#{@db_settings[:backup_dir]}/db_dump.sql"
  end
  
  # setup cron job to perform mysql database backup to "/data/#{db_settings[:backup_dir]}/db_dump.sql"
  def setup_backup(c)
    c.ssh "cp #{c.base_tmp_dir}/mysql-backup /etc/cron.d/mysql-backup"
  end
  
  # start monit, which will also start mysql
  def start_monit(c)
    c.ssh "/etc/init.d/monit start"
  end
end