some deploy from legacy project

deploy.rb

# Automatically precompile assets
load "deploy/assets"

# Execute "bundle install" after deploy, but only when really needed
require "bundler/capistrano"
# RVM integration
require "rvm/capistrano"

set :application, "app name"
set :rails_env, :production
set :domain, "your domain"

set :use_sudo, false
set :rvm_ruby_string, 'rvmrc'
set :rvm_type, :user

set :hostingserver, "server"
set :user,          "user on server"
set :port,          22

set :scm, :git # You can set :scm explicitly or Capistrano will make an intelligent guess based on known version control directory names
set :repository,  "your git repository"
set :branch,      "branch from deploy"

set :bundle_without, [:darwin, :development, :test]

# Deploy via github
set :deploy_via, :remote_cache
set :deploy_to, "deploy folder"

set :shared_files,  %w(config/database.yml config/config.yml public/uploads)

role :web, hostingserver                          # Your HTTP server, Apache/etc
role :app, hostingserver                          # This may be the same as your `Web` server
role :db,  hostingserver, :primary => true          # This is where Rails migrations will run
#role :db,  "your slave db-server here"                  # No slave at this moment

# Install RVM and Ruby before deploy
before "deploy:setup", "rvm:install_rvm"
before "deploy:setup", "rvm:install_ruby"

after "deploy:setup", "deploy:set_rvm_version"

after "deploy:finalize_update", "deploy:update_shared_symlinks"

after "deploy", "deploy:migrate"
# Unicorn config
set :unicorn_config, "#{current_path}/config/unicorn.rb"
set :unicorn_binary, "bash -c 'bundle exec unicorn_rails -c #{unicorn_config} -E #{rails_env} -D'"
set :unicorn_pid, "#{current_path}/tmp/pids/unicorn.pid"

namespace :deploy do
  task :start, :roles => :app, :except => { :no_release => true } do
    # Start unicorn server using sudo (rails)
    run "cd #{current_path} && #{unicorn_binary}"
  end

  task :stop, :roles => :app, :except => { :no_release => true } do
    run "if [ -f #{unicorn_pid} ]; then kill `cat #{unicorn_pid}`; fi"
  end

  task :graceful_stop, :roles => :app, :except => { :no_release => true } do
    run "if [ -f #{unicorn_pid} ]; then kill -s QUIT `cat #{unicorn_pid}`; fi"
  end

  task :reload, :roles => :app, :except => { :no_release => true } do
    run "if [ -f #{unicorn_pid} ]; then kill -s USR2 `cat #{unicorn_pid}`; fi"
  end

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

  task :set_rvm_version, :roles => :app, :except => { :no_release => true } do
    run "rvm use #{rvm_ruby_string}"
  end

  task :update_shared_symlinks do
    shared_files.each do |path|
      run "ln -nfs #{File.join(deploy_to, "shared", path)} #{File.join(release_path, path)}"
    end
  end

  desc "reload the database with seed data"
  task :seed do
    run "cd #{current_path}; bundle exec rake db:seed RAILS_ENV=#{rails_env}"
  end

  # Precompile assets only when needed
  namespace :assets do
    task :precompile, :roles => :web, :except => { :no_release => true } do
      # If this is our first deploy - don't check for the previous version
      if remote_file_exists?(current_path)
        from = source.next_revision(current_revision)
        if capture("cd #{latest_release} && #{source.local.log(from)} vendor/assets/ app/assets/ | wc -l").to_i > 0
          run %Q{cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:precompile}
        else
          logger.info "Skipping asset pre-compilation because there were no asset changes"
        end
      else
        run %Q{cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:precompile}
      end
    end
  end
end

# Helper function
def remote_file_exists?(full_path)
  'true' ==  capture("if [ -e #{full_path} ]; then echo 'true'; fi").strip
end

desc "tail production log files"
task :tail_logs, :roles => :app do
  run "tail -f #{shared_path}/log/production.log" do |channel, stream, data|
    trap("INT") { puts 'Interupted'; exit 0; }
    puts  # for an extra line break before the host name
    puts "#{channel[:host]}: #{data}"
    break if stream == :err
  end
end