Allow to set log_format per frontend

templates/frontend.cfg

@@ -100,6 +100,10 @@ frontend {{ item.name }} {%if item.ip is defined %}{{ item.ip }}{% endif %}{%if
         {{ macros.http_response(item.http_response) }}
     {%- endif -%}
 
+    {%- if item.log_format is defined -%}
+        log-format "{{ item.log_format }}"
+    {% endif -%}
+
     {%- if item.default_backend is defined -%}
         default_backend {{ item.default_backend }}
     {% endif -%}