deploy use unicorn and nginx

deploy.rb

set :application, "hermes"
set :repository,  "git@your_repository:hermes.git"
set :user, 'root'
set :use_sudo, false

set :deploy_via, :remote_cache
set :scm, :git
# Or: `accurev`, `bzr`, `cvs`, `darcs`, `git`, `mercurial`, `perforce`, `subversion` or `none`

role :web, "xxx.com"                          # Your HTTP server, Apache/etc
role :app, "xxx.com"                          # This may be the same as your `Web` server
role :db,  "xxx.com", :primary => true # This is where Rails migrations will run
#role :db,  "your slave db-server here"
set :deploy_to, "/path/to/app/#{application}"
# if you're still using the script/reaper helper you will need
# these http://github.com/rails/irs_process_scripts

# If you are using Passenger mod_rails uncomment this:
# namespace :deploy do
#   task :start do ; end
#   task :stop do ; end
#   task :restart, :roles => :app, :except => { :no_release => true } do
#     run "#{try_sudo} touch #{File.join(current_path,'tmp','restart.txt')}"
#   end
# end

before "deploy", "deploy:bundle_gems"
before "deploy:restart", "deploy:bundle_gems"
#after "deploy:bundle_gems", "deploy:restart"
#after "deploy:bundle_gems", "deploy:restart"
set :unicorn_pid, "#{deploy_to}/shared/pids/unicorn.pid"
set :bundle, "/var/lib/gems/1.9.1/bin//bundle"
set :unicorn_rails, "/var/lib/gems/1.9.1/bin//unicorn_rails"

namespace :deploy do
  task :bundle_gems do
    run "cd #{deploy_to}/current && #{bundle} install --path vendor/gems" 
  end

  task :start, :roles => :app, :except => { :no_release => true} do
    run "#{unicorn_rails} -c #{deploy_to}/current/config/unicorn.rb -D -E production"
  end

  task :stop, :roles => :app, :except => { :no_release => true} do
    run "kill `cat #{unicorn_pid}`" 
  end
  
  task :reload, :roles => :app, :except => { :no_release => true } do
    run "kill -s USR2 `cat #{unicorn_pid}`"
  end

  task :restart, :roles => :app, :except => { :no_release => true } do
    stop
    start
  end
end

after "migration:reload", "deploy:restart"
namespace :migration do
  task :reload, :roles => :app, :except => { :no_release => true } do
    run "cd #{deploy_to}/current && rake db:drop:all && rake db:migrate RAILS_ENV='production' && rake db:seed RAILS_ENV='production'"
  end
end