check for realip module

nginx/templates/config.jinja

@@ -13,7 +13,7 @@ events {
 }
 
 http {
-    {% if 'set_real_ips' in nginx -%}
+    {% if 'set_real_ips' in nginx and salt['cmdmod.retcode']('nginx -V 2>&1 | grep http_realip_module') == 0 -%}
     {% for ip in nginx.get('set_real_ips', {}).get('ips', []) -%}
     set_real_ip_from {{ ip }};
     {% endfor -%}