Capistrano 3

Capfile

require 'capistrano/setup'
require 'capistrano/deploy'
require 'capistrano/rvm'
require 'capistrano/bundler'

# Loads custom tasks from `lib/capistrano/tasks' if you have any defined.
Dir.glob('lib/capistrano/tasks/*.cap').each { |r| import r }

deploy.rb

set :application, "#{fetch(:stage)}.EXAMPLE.com"
set :deploy_to,   "/home/USER/apps/#{fetch(:application)}"

set :rvm_path,         '~/.rvm'
set :rvm_default_path, '~/.rvm'
set :rvm_ruby_version, '2.1.0@EXAMPLE'
set :rvm_type,         :user

server 'coachonrails.com', user: 'USER', roles: %w{web app db assets}

set :repo_url,     'git@github.com:USER/EXAMPLE.git'
set :copy_exclude, ['.git', '.gitignore']
set :scm,          :git
set :use_sudo,     false

set :linked_files, %w{config/database.yml config/secrets.yml}
set :linked_dirs,  %w{bin}

set :keep_releases, 10

set :normalize_asset_timestamps, false

set :pty, true

namespace :deploy do
  def unicorn_config
    "#{fetch(:app_path)}/config/unicorn.rb"
  end

  def unicorn_pid
    "#{fetch(:app_path)}/tmp/pids/unicorn.pid"
  end

  def unicorn_old_pid
    "#{unicorn_pid}.oldbin"
  end

  def unicorn_get_pid(pid_file = unicorn_pid)
    "`cat #{pid_file}`"
  end

  def unicorn_get_old_pid
    unicorn_get_pid(unicorn_old_pid)
  end

  def unicorn_is_running?
    remote_process_exists? unicorn_pid
  end

  def unicorn_old_is_running?
    remote_process_exists?(unicorn_old_pid)
  end

  def remote_process_exists?(pid_file)
    "[ -e #{pid_file} ] && kill -0 `cat #{pid_file}` > /dev/null 2>&1"
  end

  def unicorn_send_signal(signal, pid = unicorn_get_pid)
    "kill -s #{signal} #{pid}"
  end

  def unicorn_start
    if test "[ -e '#{unicorn_pid}' ]"
      if test "kill -0 `cat #{unicorn_pid}` > /dev/null 2>&1"
        execute :echo, 'Unicorn is already running'
        execute :exit, 0
      end

      execute :rm, unicorn_pid
    end

    within fetch(:app_path) do
      with rails_env: fetch(:rails_env) do
        execute :echo,   'Starting Unicorn'
        execute :bundle, "exec unicorn_rails -c #{unicorn_config} -D -E #{fetch(:rails_env)}"
      end
    end
  end

  def unicorn_kill(signal)
    if test unicorn_is_running?
      execute :echo, 'Stopping Unicorn...'
      execute unicorn_send_signal(signal)
    else
      execute :echo, 'Unicorn is not running.'
    end
  end

  def unicorn_duplicate
    unicorn_is_running? ? unicorn_send_signal('USR2') : unicorn_start
  end

  desc 'Start Unicorn master process'
  task :start do
    on roles(:app) do
      unicorn_start
    end
  end

  desc 'Stop Unicorn'
  task :stop do
    on roles(:app) do
      unicorn_kill('QUIT')
    end
  end

  desc 'Restart Unicorn'
  task :restart do
    on roles(:app) do
      unicorn_duplicate
      execute :sleep, 2

      if unicorn_old_is_running?
        unicorn_send_signal('QUIT', unicorn_get_old_pid)
      end
    end
  end

  desc 'Immediately shutdown Unicorn'
  task :shutdown do
    on roles(:app) do
      unicorn_kill('TERM')
    end
  end

  task :migrate do
    on primary(:db) do
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :bundle, 'exec rake db:migrate'
        end
      end
    end
  end

  namespace :assets do
    task :precompile do
      on roles(:web) do
        within release_path do
          with rails_env: fetch(:rails_env) do
            execute :bundle, 'exec rake assets:precompile'
          end
        end
      end
    end
  end

  before 'assets:precompile', 'bower:install'
  after  :updated,            'deploy:assets:precompile'
  after  :updated,            'deploy:migrate'
  after  :finishing,          'deploy:cleanup'
end

namespace :bower do
  task :install do
    on roles(:app) do
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :bower, 'install --quiet'
        end
      end
    end
  end

  task :prune do
    on roles(:app) do
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :bower, 'prune'
        end
      end
    end
  end

  after  :install, 'bower:prune'
end

staging.rb

set :rails_env,   :staging
set :stage,       :staging
set :branch,      :staging

set :application, "#{fetch(:stage)}.EXAMPLE.com"
set :deploy_to,   "/home/USER/apps/#{fetch(:application)}"
set :app_path,    "#{fetch(:deploy_to)}/current"