Adds parameter to configure HAProxy defaults balance

Introduce new option "haproxy_defaults_balance" to set balance in
defaults section.

Change-Id: Iaf12717ffac94ac2308758bd8ec87f088af26b69
Closes-Bug: #1773178

ansible/roles/haproxy/defaults/main.yml

@@ -39,6 +39,9 @@ haproxy_image_full: "{{ haproxy_image }}:{{ haproxy_tag }}"
 haproxy_client_timeout: "1m"
 haproxy_server_timeout: "1m"
 
+# Check http://www.haproxy.org/download/1.5/doc/configuration.txt for available options
+haproxy_defaults_balance: "roundrobin"
+
 haproxy_glance_api_client_timeout: "6h"
 haproxy_glance_api_server_timeout: "6h"
 

ansible/roles/haproxy/templates/haproxy.cfg.j2

@@ -33,6 +33,7 @@ defaults
   timeout client {{ haproxy_client_timeout }}
   timeout server {{ haproxy_server_timeout }}
   timeout check 10s
+  balance {{ haproxy_defaults_balance }}
 
 listen stats
    bind {{ api_interface_address }}:{{ haproxy_stats_port }}