Move vars to defaults as otherwise they may not be overridden.

defaults/main.yml

@@ -1,3 +1,8 @@
 ---
+nginx_user: "nginx"
+nginx_worker_processes: "1"
+nginx_worker_connections: "8192"
+nginx_client_max_body_size: "64m"
+nginx_keepalive_timeout: "65"
 nginx_remove_default_vhost: false
 nginx_default_vhost_path: /etc/nginx/sites-enabled/default

vars/main.yml

@@ -1,6 +1 @@
 ---
-nginx_user: "nginx"
-nginx_worker_processes: "1"
-nginx_worker_connections: "8192"
-nginx_client_max_body_size: "64m"
-nginx_keepalive_timeout: "65"