Use Puma

Procfile

@@ -1 +1 @@
-web: rvmsudo bundle exec unicorn -p 9000
+web: bundle exec puma -C config/puma.rb

config/puma.rb

@@ -0,0 +1,15 @@
+max_threads_count = ENV.fetch("RAILS_MAX_THREADS", 5)
+min_threads_count = ENV.fetch("RAILS_MIN_THREADS") { max_threads_count }
+threads min_threads_count, max_threads_count
+
+port ENV.fetch("PORT", 3000)
+
+environment ENV.fetch("RAILS_ENV", "development")
+
+pidfile ENV.fetch("PIDFILE", "tmp/pids/server.pid")
+
+workers ENV.fetch("WEB_CONCURRENCY", 2)
+
+preload_app!
+
+plugin :tmp_restart