deploy.rb

# in your deploy make sure you have git as scm and some load path hacks so that the capistrano and deploy override are seen from shared or 
# whatever you want to call it.
$LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', '..', 'shared'))
require 'shared'
require 'git_deploy_override'

set :deploy_via, :git_sync

git_deploy_override.rb

Capistrano::Configuration.instance(:must_exist).load do

  _cset(:current_release)   { current_path }
  _cset(:previous_release) { nil } # No previous release will work on a dir format


  def latest_release
    current_path
  end

  def current_release
    current_path
  end

  # =============================================================================
  # OVERRIDE CAPISTRANO TASKS TO NEUTRALIZE THEM
  # =============================================================================

  namespace :deploy do
    task :finalize_update, :except => { :no_release => true } do
      run "chmod -R g+w #{current_path}" if fetch(:group_writable, true)

      # mkdir -p is making sure that the directories are there for some SCM's that don't
      # save empty folders
      run <<-CMD
        rm -rf #{current_path}/log #{current_path}/public/system #{current_path}/tmp/pids &&
        mkdir -p #{current_path}/public &&
        mkdir -p #{current_path}/tmp &&
        ln -s #{shared_path}/log #{current_path}/log &&
        ln -s #{shared_path}/system #{current_path}/public/system &&
        ln -s #{shared_path}/pids #{current_path}/tmp/pids
      CMD

      if fetch(:normalize_asset_timestamps, true)
        stamp = Time.now.utc.strftime("%Y%m%d%H%M.%S")
        asset_paths = %w(images stylesheets javascripts).map { |p| "#{current_path}/public/#{p}" }.join(" ")
        run "find #{asset_paths} -exec touch -t #{stamp} {} ';'; true", :env => { "TZ" => "UTC" }
      end
    end

    # This simply sets the /app/current symlink from a release.
    # Now app/current is always current, so this is meaningless now.
    task :symlink do
      # noop
    end

    # Rollback could cause some bad things, so just noop the delete tasks.
    namespace :rollback do
      task :revision, :except => { :no_release => true } do
        strategy.rollback!
      end

      task :cleanup, :except => { :no_release => true } do
        # noop
      end
    end


  end

end

git_sync.rb

require 'capistrano/recipes/deploy/strategy/remote'

module Capistrano
  module Deploy
    module Strategy

      # Implements the deployment strategy that keeps a checkout of
      # the source code on each remote server. Each deploy simply updates the
      # checkout
      class GitSync < Remote
        # Executes the SCM command for this strategy and writes the REVISION
        # mark file to each host.
        def deploy!
          update_repository_cache
          mark
        end

        # This may not be needed
        def check!
          super.check do |d|
            d.remote.writable(shared_path)
          end
        end

        def rollback!
          filter_out = " sort -n -r | head -n 2 | tail -n 1 "
          run "cd #{repository_path} && ROLLBACK_TAG=`#{scm} tag -l | grep RELEASE | #{filter_out}` && #{scm} checkout $ROLLBACK_TAG"
          run "cd #{repository_path} && #{scm} submodule update"
        end

        private

        def repository_path
          configuration[:current_path]
        end

        def update_repository_cache
          logger.trace "updating the repository checkout on all servers using #{repository_path} and revision #{revision}"
          command = "if [ -d #{repository_path} ]; then " +
            "#{source.sync(revision, repository_path)}; " +
            "else #{source.checkout(revision, repository_path)}; fi"
          scm_run(command)
        end

        # Returns the command which will write the identifier of the
        # revision being deployed to the REVISION file on each host.
        def mark
          run "(echo #{revision} > #{repository_path}/REVISION)"
          tag_release
        end

        def tag_release
          tag_name = "RELEASE_#{Time.now.strftime('%Y%m%d%H%M%S')}"
          run "cd #{repository_path} && #{scm} tag #{tag_name}"
        end
      end

    end
  end
end