capistrano mysqldump hack

db_cloning.rb

# Used for copying ALL data from one Rails env to another.
# To prep the "training" environment with a copy of the latest production dataset:
# $ cap training db:clone_from_production
#
# Bonus feature: You can specify which host to go via, useful for tunneling:
# $ cap development db:clone_from_staging HOSTS=ssh-gateway.remotesite.com

namespace :db do
  CONFIG = YAML.load(ERB.new(File.read("config/database.yml")).result)
  #Premature optimization: supports several source environments! :-)
  %w(production staging).each do |src_env|
    desc "Copies schema+data FROM #{src_env} TO target environment"
    task :"clone_from_#{src_env}", :roles => :db, :only => { :primary => true } do 
      on_rollback { delete_tmp_files } #doesn't seem to work :(
      abort "Error: Importing #{src_env.upcase} to #{environment.upcase} is sort of like running in circles..." if environment == src_env
      abort "HOLD IT - we do NOT want to mess with production." if "production" == environment
      
      ENV['src_env'] = src_env
      transaction do
        load_into_database
      end
    end
    after "db:clone_from_#{src_env}", "db:delete_tmp_files"
  end

  task :delete_tmp_files, :roles => :db, :only => { :primary => true } do
    system "rm #{ENV['local_dumpfile']} || true"
    run "rm #{ENV['remote_dumpfile']} || true"
  end
  
  task :load_into_database do
    SRC = CONFIG[ENV['src_env']]
    dumpname = "#{Time.now.strftime('%Y%m%d%H%M%S')}_#{SRC['database']}.sql.gz"
    ENV['remote_dumpfile'] = remote_dumpfile = "/tmp/#{dumpname}"
    
    DST = CONFIG[environment]
    ENV['local_dumpfile'] = local_dumpfile = "#{ENV['TMP'] || '/tmp'}/#{dumpname}"
    
    run <<-END
umask 177
mysqldump -h#{SRC['host']} -P#{SRC['port']} --user=#{SRC['username']} --password=#{SRC['password']} #{SRC['database']} \
| gzip > #{remote_dumpfile}
END
    get "#{remote_dumpfile}", "#{local_dumpfile}"
    
    print "Local dumpfile: "
    system "du -h #{local_dumpfile}"
    answer = "y" if ENV.has_key?("YES")
    answer ||= Capistrano::CLI.ui.ask("You are about to *REPLACE* all data in \"#{environment}\", continue? (y/n?):")
    if answer == "y" 
      system <<-END
mysql -B -h#{DST['host']} -P#{DST['port']} --user=#{DST['username']} --password=#{DST['password']} -e"DROP DATABASE IF EXISTS #{DST['database']};CREATE DATABASE #{DST['database']};"
gzip -dc #{local_dumpfile} | \
mysql -B -h#{DST['host']} -P#{DST['port']} --user=#{DST['username']} --password=#{DST['password']} #{DST['database']}
END
    else
      puts "Alright - aborted."
      run "false"
    end
  end
end