Use UA filter in mailman apache vhost

We're noticing that mailman's uwsgi queue is filling up. Before we try
to extend the queue apply our user agent filter to apache to reduce the
number of requests that hit the queue in the first place.

Change-Id: Ib821a7fffa6239a9affcc4c6698eef2dc9378cd1

playbooks/roles/mailman3/tasks/main.yaml

@@ -164,6 +164,11 @@
       - apache2-utils
     state: present
 
+- name: Add UA filter macro to apache config
+  # This is used in the mailman apache vhost.
+  include_role:
+    name: apache-ua-filter
+
 - name: Apache modules
   apache2_module:
     state: present

playbooks/roles/mailman3/templates/mailman.vhost.j2

@@ -12,6 +12,8 @@
 
   CustomLog ${APACHE_LOG_DIR}/{{ mailman_sites.0.listdomain }}-access.log combined
 
+  Use UserAgentFilter
+
   # Use mod rewrite to redirect as we want to preserve the FQDN for each
   # mm3 vhost.
   RewriteEngine On
@@ -45,6 +47,10 @@
     Require local
   </Location>
 
+  # This macro relies on mod rewrite rules so put it before any of the
+  # actual rewrites we want to perform.
+  Use UserAgentFilter
+
   RewriteEngine On
   RewriteRule ^/robots.txt$ /var/www/robots/robots.txt [L]
   RewriteRule "/pipermail/(.*)" "/var/lib/mailman/web-data/mm2archives/%{HTTP_HOST}/public/$1"