db_backup.cap

desc "Backup the database"
namespace :db do
	task :backup do
		on roles(:db) do |host|
			backup_path = "#{fetch(:deploy_to)}/backups"
			execute :mkdir, "-p #{backup_path}"
			basename = 'database'
			
			username, password, database, host = get_remote_database_config(fetch(:stage))
			debug "#{username}, #{password}, #{database}"

			filename = "#{basename}_#{fetch(:stage)}_#{database}_#{Time.now.strftime '%Y-%m-%d_%H:%M:%S'}.sql.bz2"
			debug "We will backup to file: #{backup_path}/#{filename}"

			hostcmd = host.nil? ? '' : "-h #{host}" 
			execute :mysqldump, "-u #{username} --password='#{password}' --databases #{database} #{hostcmd} | bzip2 -9 > #{backup_path}/#{filename}"

			purge_old_backups "#{basename}", "#{backup_path}"
		end
	end

	def get_remote_database_config(db)      
      remote_config = capture("cat #{shared_path}/config/database.yml")
      database = YAML::load(remote_config)
      return database["#{db}"]['username'], database["#{db}"]['password'], database["#{db}"]['database'], database["#{db}"]['host']    
    end

    def purge_old_backups(basename,backup_path)
      max_keep = fetch(:keep_db_backups, 5).to_i
      backup_files = capture("ls -t #{backup_path}/#{basename}*").split.reverse
      if max_keep >= backup_files.length
        info "No old database backups to clean up"
      else
        info "Keeping #{max_keep} of #{backup_files.length} database backups"
        delete_backups = (backup_files - backup_files.last(max_keep)).join(" ")
        execute :rm, "-rf #{delete_backups}"
      end
    end
end