Ruby/Ruby on Rails/デプロイ/Capistrano/MySQLのバックアップとリストア

before "deploy:migrate", "backup:mysql"

# バックアップ用
namespace :backup do
  desc "Backup remote production DB with mysqldump"
  task :mysql, :roles => :db, :only => { :primary => true } do
    require 'yaml'

    filename = "#{application}.#{domain.gsub(".", "_")}.#{Time.now.strftime("%Y-%m-%d_%H-%M-%S")}.sql.bz2"
    file = "#{shared_path}/backups/#{filename}"
    on_rollback { delete file }

    # DBの設定読み込み
    db = YAML::load(ERB.new(IO.read(File.join(File.dirname(__FILE__), 'database.yml'))).result)['production']

    # フォルダ作成
    run "mkdir -p #{shared_path}/backups"
    # MYSQL dump
    run "mysqldump -u #{db['username']} --password=#{db['password']} #{db['database']} | bzip2 -c > #{file}"  do |ch, stream, data|
      puts data
    end
    # 手元に持ってくる
    backup_dir = File.dirname(__FILE__) + "/../../backups/"
    FileUtils.mkdir_p backup_dir
    get file, "#{backup_dir}/#{filename}"
  end

  desc "Restore DB by mysqldumped mysql file(-S sql=dumpled_filename)"
  task :restore_mysql, :roles => :db do
    filename = sql
    unless sql   # (実は意味なし)そもそも-S sql=〜〜で書かないとsqlないと言われてエラーになる
      abort "error: specified -S=dumped_filename"
    end

    unless Capistrano::CLI.ui.agree("Confirm replace and restore DB data? (y/n)")
      abort "Restore Canceled..."
    end

    file = "#{filename}"
    filename_only = File::basename(filename)
    # tmp/~~~~.sql.bz2
    out_file = "/tmp/#{filename_only}"
    # tmp/~~~~.sql
    out_sql_file = File.join(File::dirname(out_file), File::basename(out_file, ".*"))
    # すでにファイルがあると解凍できないので消しとく
    run "rm #{out_sql_file}; true"
    #on_rollback { delete out_file; delete out_sql_file }

    # DBの設定読み込み
    db = YAML::load(ERB.new(IO.read(File.join(File.dirname(__FILE__), 'database.yml'))).result)['production']
    # bz2転送
    upload file, out_file
    # 解凍
    run "bunzip2 #{out_file}"
    # リストア
    run "mysql #{db['database']} -u #{db_user} -p#{db['password']} < #{out_sql_file}"
    run "rm #{out_sql_file}; true"
  end
end