gistfile1.rb

namespace :db do
  desc "Download the a full dump of the production database into the development database"
  task :pull do
    config = YAML::load(File.open(File.join('config', 'database.yml')))

    dump_database_remotely(config['production'], remote_file)

    compress_backup_remotely(remote_file)

    download_backup(remote_file(:compressed), local_file(:compressed))

    inflate_backup(local_file(:compressed))

    import_database(config['development'], local_file)
    
    cleanup_remotely(remote_file(:compressed))

    cleanup_locally(local_file(:uncompressed), local_file(:compressed))
  end
  
  def remote_file(state = :uncompressed)
    File.join("#{current_path}", 'tmp', filename(state))
  end
  
  def local_file(state = :uncompressed)
    "tmp/" + filename(state)
  end
  
  def filename(state)
    state == :compressed ? 'db-backup.sql.gz' : 'db-backup.sql'
  end

  def dump_database_remotely(config, file)
    run "mysqldump #{mysql_connection_string(config)} > #{file}"
  end
  
  def compress_backup_remotely(file)
    run "gzip -f #{file}"
  end
  
  def download_backup(remote_file, local_file)
    download remote_file, local_file
  end
  
  def inflate_backup(file)
    logger.debug("Inflating #{file}")
    system "gunzip -f #{file}"
  end
  
  def import_database(config, file)
    command = "mysql #{mysql_connection_string(config)} < #{file}"
    logger.debug("Importing #{file} with `#{command}`")

    system command
  end
  
  def cleanup_remotely(*files)
    files.each { |file| run "rm #{file}" }
  end
  
  def cleanup_locally(*files)
    files.each do |file|
      system "rm -f #{file}"
      logger.debug("Deleted #{file}")
    end
  end
  
  def mysql_connection_string(config)
    string = " #{config['database']}"
    string << " -h#{config['host']}" if config['host']
    string << " -u#{config['username']}" if config['username']
    string << " -p#{config['password']}" if config['password']

    string
  end
end