Disable TLS 1.1 on haproxy

While it is possible to implement countermeasures against some attacks
on TLS, migrating to a later version of TLS (TLS 1.2 is strongly
encouraged) is the only reliable method to protect against
the current protocol vulnerabilities.[1]

[1] https://blog.pcisecuritystandards.org/are-you-ready-for-30-june-2018-sayin-goodbye-to-ssl-early-tls

Change-Id: I44f67e3a49bb00fea069d29c46b3e86404c7df0b

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

@@ -16,7 +16,7 @@ global
   stats socket /var/lib/kolla/haproxy/haproxy.sock group kolla mode 660
 {% if kolla_enable_tls_external | bool %}
   ssl-default-bind-ciphers DEFAULT:!MEDIUM:!3DES
-  ssl-default-bind-options no-sslv3 no-tlsv10
+  ssl-default-bind-options no-sslv3 no-tlsv10 no-tlsv11
   tune.ssl.default-dh-param 4096
 {% endif %}
 

releasenotes/notes/disable_tlsv11-51d6be67d593f7ab.yaml

+---
+security:
+  - |
+    Disable TLS 1.1 on haproxy for external network if
+    tls is enabled.