require 'find' 
  namespace :db do  desc "Backup the database to a file. Options: DIR=base_dir RAILS_ENV=production MAX=20"
    task :backup => [:environment] do
      datestamp = Time.now.strftime("%Y-%m-%d_%H-%M-%S")    
      base_path = ENV["DIR"] || "db"
      backup_base = File.join(base_path, 'backup')
      backup_folder = File.join(backup_base, datestamp)
      backup_file = File.join(backup_folder, "#{RAILS_ENV}_dump.sql.gz")    
      File.makedirs(backup_folder)    
      db_config = ActiveRecord::Base.configurations[RAILS_ENV]   
      sh "mysqldump -u #{db_config['username'].to_s} #{'-p' if db_config['password']}#{db_config['password'].to_s} --opt #{db_config['database']} | gzip -c > #{backup_file}"     
      dir = Dir.new(backup_base)
      all_backups = dir.entries[2..-1].sort.reverse
      puts "Created backup: #{backup_file}"     
      max_backups = ENV["MAX"] || 20
      unwanted_backups = all_backups[max_backups.to_i..-1] || []
      for unwanted_backup in unwanted_backups
      FileUtils.rm_rf(File.join(backup_base, unwanted_backup))
      puts "deleted #{unwanted_backup}"
    end
    puts "Deleted #{unwanted_backups.length} backups, #{all_backups.length - unwanted_backups.length} backups available"
  end
end