Missing option

templates/haproxy.cfg.j2

@@ -148,6 +148,7 @@ frontend docker_ft
 backend swarm_api_bck
     mode http
 {% if docker_swarm_api_check_availability %}
+    option httpchk
     http-check send meth HEAD uri /version ver HTTP/1.1 hdr Host localhost
     http-check expect rstatus (2|3)[0-9][0-9]
 {% endif %}