HAProxy backend connection limits

The default connection limits for backends is 2000
however, mariadb defaults to a max of 10000 conections,
therefore changing this limit to match the mariadb limit.

'haproxy_max_connections' also needs to be bumped
for this to work.

Change-Id: I5ded328485855f3f3d4390282040b0d89d08d997

ansible/roles/haproxy/defaults/main.yml

@@ -45,9 +45,11 @@ syslog_haproxy_facility: "local1"
 keepalived_traffic_mode: "multicast"
 
 # Extended global configuration, optimization options.
-haproxy_max_connections: 4000
+haproxy_max_connections: 40000
 haproxy_processes: 1
 haproxy_process_cpu_map: "no"
+# Matches the mariadb 10000 max connections limit
+haproxy_defaults_max_connections: 10000
 
 haproxy_dimensions: "{{ default_container_dimensions }}"
 keepalived_dimensions: "{{ default_container_dimensions }}"

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

@@ -30,6 +30,7 @@ defaults
     timeout server {{ haproxy_server_timeout }}
     timeout check {{ haproxy_check_timeout }}
     balance {{ haproxy_defaults_balance }}
+    maxconn {{ haproxy_defaults_max_connections }}
 
 listen stats
    bind {{ api_interface_address }}:{{ haproxy_stats_port }}

releasenotes/notes/increase-haproxy-max-connections-df6aff5c82fdef24.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    The default connection limit for HAProxy backends is 2000 however, MariaDB
+    defaults to a max of 10000 conections. This has been changed to match the
+    MariaDB limit.
+
+    'haproxy_max_connections' has also been increased to 40000 to accommodate
+    this.