Check if backend if alive

lb-common/overlay/opt/frontend/config/fidusmd/haproxy.j2

@@ -5,3 +5,12 @@
     use_backend {{ site_name }}__default
 {% endblock usebackend %}
 
+{% block backend %}
+{{ output_backends(backends,
+      config=[
+      'cookie SERVERID insert indirect nocache',
+      'option httpchk'
+      ]
+   )
+}}
+{% endblock backend %}