Transfer from Capistrano 2 to Capistrano 3

New Capfile

# Load DSL and Setup Up Stages
require 'capistrano/setup'

# Includes default deployment tasks
require 'capistrano/deploy'


require 'capistrano/rvm'
require 'capistrano/bundler'
require 'capistrano/rails/assets'
require 'capistrano/rails/migrations'
require "whenever/capistrano"
require 'capistrano/sidekiq'


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

New deploy.rb

# config valid only for Capistrano 3.1
lock '3.1.0'

set :application, "CoolApplication"
set :repository,  "your@git.location"
set :sidekiq_role, :sidekiqer
set :rvm_ruby_version, '2.0.0-p247@global'

set :linked_files, %w{config/database.yml config/application.yml}


set :linked_dirs, %w{public/uploads public/blog}
set :ssh_options, { :forward_agent => true }


namespace :deploy do

  after :publishing, :restart
  after 'deploy:assets:precompile', 'deploy:assets:sync'
  after :finishing, 'deploy:cleanup'

end

New Gemfile

gem "capistrano-rails"
gem "capistrano-sidekiq"
gem 'capistrano-rvm'
gem 'capistrano-bundler'
gem 'whenever','~> 0.9.0' , require: false

New staging.rb

set :branch, 'develop'
set :user, 'stage_deployer'
set :domain, 'staging.your.domain'
set :rails_env, "staging"
set :deploy_to, "/home/#{fetch(:user)}/urbox"
set :sidekiq_pid, File.join("#{shared_path}", 'pids', 'sidekiq.pid')
set :stage, :staging


server "#{fetch(:domain)}", user: "#{fetch(:user)}", roles: %w{web app db asset_syncer sidekiqer}

Old Capfile

load 'deploy'
# Uncomment if you are using Rails' asset pipeline
load 'deploy/assets'
load 'config/deploy' # remove this line to skip loading any of the default tasks

Old deploy.rb

set :whenever_command, "bundle exec whenever"

set :assets_role, [:web, :shadow, :asset_syncer, :sidekiqer]

begin
  require 'capistrano_colors'
rescue LoadError
  puts "`gem install capistrano_colors` to get output more userfriendly."
end

 
set :rvm_type, :system
require "rvm/capistrano"


require 'capistrano/ext/multistage'
set :stages,        %w(production staging)
set :default_stage, "staging"

require 'bundler/capistrano'

require "whenever/capistrano"

set :application, "cool application name"
set :repository,  "your@git.location"
set :ssh_options, { :forward_agent => true }
set :scm, :git

set :deploy_via, :copy
set :git_shallow_clone, 1

set :scm_verbose, true
set :use_sudo, false
set :symlink_paths, ['config/database.yml', 'config/application.yml']


# from https://github.com/AF83/capistrano-af83/blob/master/lib/capistrano/af83/deploy/assets.rb
set :assets_dependencies, %w(app/assets lib/assets vendor/assets Gemfile.lock config/routes.rb)


namespace :deploy do

  desc "Restart passenger process"
  task :restart, :roles => [:web], :except => { :no_release => true } do

    run "touch #{current_path}/tmp/restart.txt"

  end

  task :symlink_files do
    symlink_paths.each do |path|
      run "ln -sf #{shared_path}/#{path} #{release_path}/#{path}"
    end
  end

  namespace :assets do
    task :sync, :roles => [:asset_syncer] do # you must set "shadow" server role
      run "cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:sync"
    end
  end

end

namespace :remote_rake do
  desc "Run a task on remote servers, ex: cap staging remote_rake:invoke task=cache:clear"
  task :invoke do
    run "cd #{deploy_to}/current; RAILS_ENV=#{rails_env} bundle exec rake #{ENV['task']}"
  end
end

# cap staging tail_log
task :tail_log, :roles => :app do
  run "tail -f -n 100 #{shared_path}/log/#{rails_env}.log"
end


after "deploy:finalize_update", "deploy:symlink_files"
after "deploy", "deploy:cleanup"
after "deploy:assets:precompile", "deploy:assets:sync"

set :sidekiq_cmd, "bundle exec sidekiq"
set :sidekiqctl_cmd, "bundle exec sidekiqctl"
set :sidekiq_role, :sidekiqer

require 'sidekiq/capistrano'

Old Gemfile

gem 'capistrano'
gem 'capistrano-ext'
gem 'capistrano_colors'
gem 'rvm-capistrano'
gem 'whenever', require: false

Old staging.rb

set :branch, 'develop'
set :user, 'stage_deployer'
set :domain, 'staging.your.domain'
set :rails_env, "staging"
set :deploy_to, "/home/#{user}/#{application}"

server "#{domain}", :web, :app, :db, :asset_syncer, :sidekiqer, :primary => true

restart.cap

namespace :deploy do
  desc "Restart passenger process"
  task :restart do
    on roles(:web), in: :sequence, wait: 5 do
      execute "touch", "#{release_path}/tmp/restart.txt"
    end
  end
end

sync_to_S3.cap

namespace :deploy do
	namespace :assets do
		desc "Synchronize assets to S3"
	    task :sync do 
	    	on roles(:asset_syncer) do |role| 
      			within "#{release_path}"do
      				with rails_env: "#{fetch(:rails_env)}"  do
      					execute :rake, "assets:sync"
	    			end
	    		end
	    	end
		end
  	end
end