gistfile1.rb

# http://blog.craigambrose.com/articles/2007/03/01/a-rake-task-for-database-backups
# http://edge.matrixprojects.com/2008/5/21/backing-up-your-rails-mysql-db-via-a-rake-task
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")    
    db_config     = ActiveRecord::Base.configurations[RAILS_ENV]   
      
    FileUtils.mkdir_p(backup_folder)    
  
    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}"
    puts "Created backup: #{backup_file}"     
    
    max_backups      = ENV["MAX"] || 20
    all_backups      = (Dir.entries(backup_base) - ['.', '..']).sort.reverse
    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