Sygen version of mysql backup using rake

backup.rake

require 'find'

namespace :db do

  desc "Backup the database to a file. Options: DIR=base_dir RAILS_ENV=production MAX=7 SKIP_DEV=true"

  task :backup => [:environment] do
    skip = ENV["SKIP_DEV"] || ""
    unless(RAILS_ENV == "development" && skip == "")
      base_path = ENV["DIR"] || Dir.home
      backup_base = File.join(base_path, 'backup')

      backup_file = create_folder_and_get_file_name backup_base
      sh dump_command backup_file  # run the command

      dir = Dir.new(backup_base)
      all_backups = dir.entries.select{|entry| entry.match(/\d+-\d+-\d+_\d+-\d+-\d+/)}.sort.reverse
      deleted_backups = delete_unwanted(all_backups, backup_base)

      print_remaining(all_backups - deleted_backups, backup_base)
    end
  end

  def create_folder_and_get_file_name(backup_base)
    datestamp = Time.now.strftime("%Y-%m-%d_%H-%M-%S")
    backup_folder = File.join(backup_base, datestamp)
    FileUtils.mkdir_p(backup_folder)
    File.join(backup_folder, "#{RAILS_ENV}_dump.sql.gz")
  end

  def dump_command(backup_file)
    pass = try_config_entry("password", "-p")
    port = try_config_entry("port", "-P ")
    host = try_config_entry("host", "-h ")
    puts "Creating backup: #{backup_file}"
    "mysqldump#{port}#{host} -u #{db_config["username"]}#{pass} --database #{db_config["database"]} -Q --add-drop-table | gzip -c > #{backup_file}"
  end

  def delete_unwanted(all_backups, backup_base)
    max_backups = (ENV["MAX"] || 7).to_i
    puts "Keeping #{max_backups} backup files"
    unwanted_backups = all_backups[max_backups..-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"
    unwanted_backups
  end

  def print_remaining(remaining_backups, dir)
    puts "Remaining backup files on #{dir}"
    remaining_backups.each do |backup|
      puts "\t#{backup}"
    end
  end

  def db_config
    ActiveRecord::Base.configurations[RAILS_ENV]
  end

  def try_config_entry(name, arg)
    db_config[name] ? " #{arg}#{db_config[name]}" : ""
  end
end