capistrano 3 jar deployment

java.rb

STAMP = Time.now.strftime('%H_%M_%S_%L')
ROOT = "/u/apps/#{fetch(:application)}"

def release
  "#{ROOT}/releases/#{STAMP}"
end

def current
  "#{ROOT}/current"
end

namespace :deploy do

  desc 'clears n last builds'
  task :purge do
    on roles(:all) do
        total = capture("ls -la #{ROOT}/releases | wc -l").to_i
        if(total > 9)
          execute "cd #{ROOT}/releases && ls -tr | head -n -5 | xargs sudo rm -rf"
        end
    end 
  end
  
  task :stop do
    on roles(:all) do |host|
      execute "sudo service #{fetch(:service)} stop  2>&1 | grep -E 'Unknown|waiting'"
    end
  end
  
  task :start do
    on roles(:all) do |host|
      execute :sudo, :service, fetch(:service), 'start'
    end
  end
  
  task :update do
    invoke 'deploy:purge'
    invoke 'deploy:stop'
    on roles(:all) do
      execute :sudo, :mkdir, release, '-p'
      execute :sudo, :wget, '-q', artifact(fetch(:application),ENV['build']), '-P', release
    end
    invoke 'deploy:symlink'
    invoke 'deploy:start'
  end

  task :symlink  do
    on roles(:all) do
      execute :sudo, :rm , '-f', current
      execute :sudo, :ln , '-s' , release, current
    end
  end

end