Use a variable to set the unicorn workers in nginx.

templates/nginx_unicorn.conf.j2

@@ -7,7 +7,7 @@ upstream unicorn {
     # server unix:/tmp/.sock fail_timeout=0;
 
     # for TCP setups, point these to your backend servers
-    {% for i in 0, 4 %}
+    {% for i in 0, {{ unicorn_worker_processes - 1 }} %}
     server 127.0.0.1:{{ unicorn_listen_port + i }} fail_timeout=0;
     {% endfor %}
   }