MySQL backup rake task for Rails 2.3.x

backup.rake

# put this file into directory <RAILS_ROOT>/lib/tasks
namespace :db do
  desc "Backup database"
  task :backup do
    RAILS_ENV = "development" if !defined?(RAILS_ENV)
    settings = YAML.load(File.read(File.join(Rails.root, "config", "database.yml")))[RAILS_ENV]
    
    bak_dir = ENV['BAK_DIR']
    raise(RuntimeError, "==> Error: environment variable BAK_DIR not set.") if bak_dir.blank?
    extra_parameters = ["--default-character-set=utf8"]
    extra_parameters << "-h #{settings['host']}"  unless settings['host'].blank?
    unless ENV['SKIP_TABLES'].blank?
      ENV['SKIP_TABLES'].split(",").each do |tbl|
        extra_parameters << "--ignore-table=#{settings['database']}.#{tbl}"
      end
    end
    extra = extra_parameters.empty? ? "" : extra_parameters.join(" ")
    output_file = File.join(bak_dir, "#{settings['database']}-#{Time.now.strftime('%Y%M%d-%H%M')}.sql.gz")
    system("/usr/bin/env mysqldump -u #{settings['username']} -p'#{settings['password']}' #{extra} #{settings['database']} | gzip > #{output_file}")
  end
  # usage: RAILS_ENV=production BAK_DIR=/path/to/backup SKIP_TABLES=sessions,logs bundler exec rake db:backup
end