Add ability to have different backend port.

Add the possibility to have multiple backend services running on
differents ports.

Change-Id: I1748bfc15bdf879f78aa06c385af7b6c45bde7ff

releasenotes/notes/backend_config_per_host-14cec3ec5f708934.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - HAProxy services that use backend nodes that are not
+    in the Ansible inventory can now have the ``backend_port``
+    specified in the list, along with ``name`` or ``ip_addr`` settings.
+    This allow to have the service bound to different port on different
+    backend servers.

templates/service.j2

@@ -134,10 +134,10 @@ backend {{ service.haproxy_service_name }}-back
 {% set entry = [] %}
 {% set _ = entry.append("server") %}
 {% set _ = entry.append((host_name.name | default(host_name)) | string) %}
-{% set _ = entry.append((host_name.ip_addr | default(ip_addr)) + ":" + haproxy_backend_port | string) %}
+{% set _ = entry.append((host_name.ip_addr | default(ip_addr)) + ":" + (host_name.backend_port | default(haproxy_backend_port)) | string) %}
 {% set _ = entry.append("check") %}
 {% set _ = entry.append("port") %}
-{% set _ = entry.append(haproxy_check_port | string) %}
+{% set _ = entry.append(host_name.backend_port | default(haproxy_check_port) | string) %}
 {% set _ = entry.append("inter") %}
 {% set _ = entry.append(service.interval|default(haproxy_interval) | string) %}
 {% set _ = entry.append("rise") %}