title: Capistrano doesn't create puma.pid file
body: <p>I use Capistrano to deploy my Rails app. 
  However, when I deploy my application, <code>puma.pid</code> file is not being created, which leads to a problem - I can't restart server or deploy new version with capistrano - capistrano fails to stop <code>puma</code>, because <code>puma.pid</code> don't exests and it assumes no puma processes is running. And I get <code>ADDRESS ALREADY IN USE</code> error when capistrano tries to run another version of puma.</p>
  
  <p>Here is my <code>deploy.rb</code></p>
  
  <pre><code>lock '3.4.0'
  
  set :application, 'appname'
  set :repo_url, 'giturl'
  set :deploy_to, '/home/user/appname'
  set :pty, false
  set :linked_files, %w(config/application.yml config/database.yml)
  set :linked_dirs, %w(log tmp/pids tmp/cache tmp/sockets vendor/bundle public/system public/uploads)
  set :keep_releases, 5
  set :rvm_type, :user
  set :rvm_ruby_version, '2.3.0'
  
  set :puma_rackup, -&gt; { File.join(current_path, 'config.ru') }
  set :puma_state, "#{shared_path}/tmp/pids/puma.state"
  set :puma_pid, "#{shared_path}/tmp/pids/puma.pid"
  set :puma_bind, "unix://#{shared_path}/tmp/sockets/puma.sock" # accept array for multi-bind
  set :puma_conf, "#{shared_path}/config/puma.rb"
  set :puma_access_log, "#{shared_path}/log/puma_error.log"
  set :puma_error_log, "#{shared_path}/log/puma_access.log"
  set :puma_role, :app
  set :puma_env, fetch(:rack_env, fetch(:rails_env, 'production'))
  set :puma_threads, 1
  set :puma_workers, 1
  set :puma_worker_timeout, nil
  set :puma_init_active_record, true
  set :puma_preload_app, true
  
  set :sidekiq_config, 'config/sidekiq.yml'
  set :sidekiq_log, '/dev/null'
  set :sidekiq_processes, 1
  
  set :clockwork_file, "clock.rb"
  
  namespace :deploy do
  
    desc 'Recompile all enterprise themes'
    task :recompile_themes, [:command] =&gt; 'deploy:set_rails_env' do |task, args|
      on primary(:app) do
        within current_path do
          with :rails_env =&gt; fetch(:rails_env) do
            rake 'themes:recompile'
          end
        end
      end
    end
  
    after :finishing, "deploy:recompile_themes"
  end
  
  require 'appsignal/capistrano'
  </code></pre>
  
  <p>And when I try to stop running Puma, for example, I get the following error:</p>
  
  <pre><code>...
  DEBUG [37113fcf] Running [ -f /home/user/appname/shared/tmp/pids/puma.pid ] as user@server
  DEBUG [37113fcf] Command: [ -f /home/user/appname/shared/tmp/pids/puma.pid ]
  DEBUG [37113fcf] Finished in 0.273 seconds with exit status 1 (failed).
  WARN Puma not running
  </code></pre>
  
  <p>And indeed, <code>/home/user/appname/shared/tmp/pids/puma.pid</code> file don't exists. Do I need to create it manually or something? sidekiq.pid that is also being created the same way can be found in the same directory, so I don't think it's a permissions issue.</p>
  
  <p>Any advices on how to approach this?</p>