use unicorn

Gemfile

@@ -53,4 +53,5 @@ end
 group :production do
   gem 'rails_12factor'
   gem 'pg'
+  gem 'unicorn'
 end

Gemfile.lock

@@ -60,6 +60,7 @@ GEM
       railties (>= 3.0, < 5.0)
       thor (>= 0.14, < 2.0)
     json (1.8.1)
+    kgio (2.9.2)
     mail (2.5.4)
       mime-types (~> 1.16)
       treetop (~> 1.4.8)
@@ -91,6 +92,7 @@ GEM
       activesupport (= 4.1.5)
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
+    raindrops (0.13.0)
     rake (10.3.2)
     rdoc (4.1.1)
       json (~> 1.4)
@@ -127,6 +129,10 @@ GEM
     uglifier (2.5.3)
       execjs (>= 0.3.0)
       json (>= 1.8.0)
+    unicorn (4.8.3)
+      kgio (~> 2.6)
+      rack
+      raindrops (~> 0.7)
 
 PLATFORMS
   ruby
@@ -148,3 +154,4 @@ DEPENDENCIES
   sqlite3
   turbolinks
   uglifier (>= 1.3.0)
+  unicorn

Procfile

@@ -0,0 +1 @@
+web: bundle exec unicorn -p $PORT -c ./config/unicorn.rb

config/unicorn.rb

@@ -0,0 +1,23 @@
+# config/unicorn.rb
+worker_processes Integer(ENV["WEB_CONCURRENCY"] || 3)
+timeout 15
+preload_app true
+
+before_fork do |server, worker|
+  Signal.trap 'TERM' do
+    puts 'Unicorn master intercepting TERM and sending myself QUIT instead'
+    Process.kill 'QUIT', Process.pid
+  end
+
+  defined?(ActiveRecord::Base) and
+    ActiveRecord::Base.connection.disconnect!
+end
+
+after_fork do |server, worker|
+  Signal.trap 'TERM' do
+    puts 'Unicorn worker intercepting TERM and doing nothing. Wait for master to send QUIT'
+  end
+
+  defined?(ActiveRecord::Base) and
+    ActiveRecord::Base.establish_connection
+end