Given a user with sudo (but not root) access on a remote box, the following deploy.rb script will perform a capistrano deploy of a ruby application:

 Assumptions:

1. You're using 'git'. Although svn can be used, the script targets a git setup.

2. You're using mongrel_cluster. Change the script accordingly if using passenger etc.

3. The application being deployed is dropped into a subfolder/subdirectory on the remote server. You can remove the task :recreate_public_link if you're deploying to the root of a virtual directory.

4. A user and group called 'mongrel' has been created on the remote server. This owns the running mongrel_cluster processes. Relevant permissions are set by the script.

#-----------------------------------------------------
# deploy.rb - controls deployment setup/configuration 
# using the capistrano or 'cap' deployment utility.
#-----------------------------------------------------
# requires mongrel_cluster recipes to allow restart of mongrel cluster
require 'mongrel_cluster/recipes'

set :application, "rentmanager"
set :user, "peter"
set :web_user, "apache"
set :location, "192.168.0.15"

# If you are using Passenger mod_rails uncomment this:
# if you're still using the script/reapear helper you will need
# these http://github.com/rails/irs_process_scripts

# 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

ssh_options[:forward_agent] = true

default_run_options[:pty] = true
set :scm, "git"
set :scm_user, "git"
set :repository,  "#{scm_user}@#{location}:/usr/local/share/gitrepos/#{application}.git"
set :scm_passphrase, "your password" #This is your custom users password
set :git_shallow_clone, 1
set :deploy_via, :remote_cache
set :branch, "master"
set :use_sudo, true
set :site_root, "app/rentmanager"
role :app, location
role :web, location
role :db, location, :primary=>true
set :deploy_to, "/var/www/html/test.threerock.com/#{application}"

#---------------
#mongrel details
#---------------
set :mongrel_conf, "#{deploy_to}/current/config/mongrel_cluster.yml"
set :mongrel_user, "mongrel"
set :mongrel_group, "mongrel"
set :runner, nil
set :mongrel_clean, true  # helps keep mongrel pid files clean

#-----------------------
# migration parameters
#----------------------
set :rake, "rake"
set :rails_env, "production"
set :migrate_env, ""
set :migrate_target, :latest 

before "deploy:update_code", "custom:set_permissions_for_checkout"

before "deploy:migrate", "custom:set_permissions_pre_schema_dump"
after "deploy:migrate", "custom:set_permissions_post_schema_dump"

before "deploy:migrations", "custom:set_permissions_pre_schema_dump"
after "deploy:migrations", "custom:set_permissions_post_schema_dump", "deploy:cleanup"

before "deploy:symlink", "custom:get_current_ownership"

after "deploy:symlink", "custom:update_application_controller",
      "custom:yield_current_ownership",
      "custom:set_permissions_for_runtime", 
      "custom:recreate_public_link"

namespace(:deploy) do

  desc "Restart the Mongrel processes on the app server."
  task :restart, :roles => :app do
    mongrel.cluster.stop
    sleep 2.5
    mongrel.cluster.start
  end

end

namespace(:custom) do

  desc "Change ownership of target folders and files to current user"
  task :set_permissions_for_checkout, :except => { :no_release => true } do
    #chown of files to current user
    sudo "chown -R #{scm_user}:#{scm_user} #{deploy_to}"
  end

  desc "Change ownership of target folders and files to current user"
  task :set_permissions_for_runtime, :except => { :no_release => true } do
    #chown of files to current user
    sudo "chown -R #{web_user}:#{web_user} #{deploy_to}"
    sudo "chown #{mongrel_user}.#{mongrel_group} -R #{deploy_to}/current/tmp/pids"
    sudo "chown #{mongrel_user}.#{mongrel_group} -R #{deploy_to}/current/log"
    sudo "chown #{mongrel_user}.#{mongrel_group} -R #{shared_path}/pids"
  end

  desc "Recreate link to serve public folders when hosting within subfolder"
  task :recreate_public_link do
    run <<-CMD
      cd #{deploy_to}/current/public && sudo ln -s . #{application}
    CMD
  end

  desc "Take temporary ownership of current folder to allow symlink updates"
  task :get_current_ownership do
    sudo "chown #{user}:#{user} #{release_path}"
  end

  desc "Take temporary ownership of current folder to allow symlink updates"
  task :yield_current_ownership do
    sudo "chown -R #{web_user}:#{web_user} #{release_path}"
  end

  desc "Change ownership of db folders and files to current user"
  task :set_permissions_pre_schema_dump, :except => { :no_release => true } do
    #chown of files to current user
    sudo "chown -R #{user}:#{user} #{release_path}/db"
  end

  desc "Change ownership of db folders and files to current user"
  task :set_permissions_post_schema_dump, :except => { :no_release => true } do
    #chown of files to current user
    sudo "chown -R #{web_user}:#{web_user} #{release_path}/db"
  end

  desc "Update application.rb to application_controller.rb"
  task :update_application_controller, :roles => :app do
    run <<-CMD
      cd #{deploy_to}/current/ && sudo rake rails:update:application_controller
    CMD
  end  
  task :config, :roles => :app do
    run <<-CMD
      sudo ln -nfs #{shared_path}/system/database.yml #{release_path}/config/database.yml
    CMD
  end

  desc "Creating symbolic link (custom namespace)"
  task :symlink, :roles => :app do
    run <<-CMD
      sudo ln -nfs #{shared_path}/system/uploads #{release_path}/public/uploads
    CMD
  end

end
 

</end of article>