ruby script to backup(export) docker container

dockerBackup.rb

require 'clockwork'
include Clockwork

module Clockwork
  @@rootDir = "/Users/yumu/dockerBackupDir/"
  @@hourlyFormat = "%Y%m%d_%H%M"
  @@dailyFormat = "%Y%m%d"

  def getContainerNames
    ps = `docker ps`.split("\n")
    ps.delete_at(0)
    names = Array.new
    ps.each do |l|
      names.push(l.split(/ /,0).last)
    end
    return names
  end

  def hourly
    t = Time.now
    yesterday = t - 60 * 60 * 24
    Dir.mkdir(@@rootDir) if !File.exist?(@@rootDir)

    getContainerNames.each do |name|
      dirPath = File.join(@@rootDir,name)
      Dir.mkdir(dirPath) if !File.exist?(dirPath)
      hourlyFile = t.strftime(@@hourlyFormat)+".tar"
      hourlyFilePath = File.join(dirPath,hourlyFile)
      dailyFile = t.strftime(@@dailyFormat)+".tar"
      dailyFilePath = File.join(dirPath,dailyFile)
      `docker export #{name} > #{hourlyFilePath}`
      `cp #{hourlyFilePath} #{dailyFilePath}`
      Dir::glob("#{dirPath}/????????_????.tar").each {|f|
        fDateStr = f.match(%r{#{dirPath}/(.+?).tar})[1]
        fDate = Time.strptime(fDateStr, @@hourlyFormat)
        File.delete(f) if fDate < yesterday
      }
    end
  end

  def daily
    today = Date.today
    lastweek = today - 7
    getContainerNames.each do |name|
      p name
      dirPath = File.join(@@rootDir,name)
      dailyFile = today.strftime(@@dailyFormat)+".tar"
      dailyFilePath = File.join(dirPath,dailyFile)
      Dir::glob("#{dirPath}/????????.tar").each {|f|
        fDateStr = f.match(%r{#{dirPath}/(.+?).tar})[1]
        fDate = Time.strptime(fDateStr, @@dailyFormat)
        File.delete(f) if ((fDate < lastweek) && (fDate.day != 1))
      }
    end
  end

  handler do |job|
    self.send(job.to_sym)
  end

  every(1.hour, 'hourly')
  every(1.day, 'daily')
end