archwiki: enable memcached by default and make ram configurable

Introduce a variable to set the memcached memory size.

roles/archwiki/defaults/main.yml

@@ -9,6 +9,7 @@ archwiki_question_answer_file: '/srv/http/archwiki/registration-question-answer.
 
 archwiki_socket: '/run/php-fpm/archwiki.socket'
 archwiki_memcached_socket: '/run/memcached/archwiki.sock'
+archwiki_memcached_memory: 2048
 
 archwiki_db: 'archwiki'
 archwiki_db_host: 'localhost'

roles/archwiki/tasks/main.yml

@@ -112,7 +112,7 @@
   service: name=archwiki-question-updater.service state=started
 
 - name: start and enable archwiki memcached
-  service: name=archwiki-memcached.service state=started
+  service: name=archwiki-memcached.service enabled=yes state=started
 
 - name: ensure question answer file exists and set permissions
   file: state=file path="{{archwiki_question_answer_file}}" owner=root group=root mode=0644

roles/archwiki/templates/archwiki-memcached.service.j2

@@ -5,7 +5,7 @@ After=network.target
 [Service]
 User={{ archwiki_user }}
 Group=memcached
-ExecStart=/usr/bin/memcached -s {{ archwiki_memcached_socket }} -m 512 -o modern
+ExecStart=/usr/bin/memcached -s {{ archwiki_memcached_socket }} -m {{ archwiki_memcached_memory }} -o modern
 Restart=always
 NoNewPrivileges=yes
 PrivateTmp=yes