Use memcached as koschei dogpile cache backend

roles/koschei/backend/templates/config.cfg.j2

@@ -106,6 +106,14 @@ config = {
         "topic_re": r'\.prod\.pkgdb\.',
         {% endif %}
         "sync_tracked": True,
+        "cache": {
+            "backend": "dogpile.cache.memcached",
+            "expiration_time": 300,
+            "arguments": {
+                "url": "memcached01",
+                "distributed_lock": True,
+            },
+        },
     },
     "frontend": {
         "auto_tracking": True,

roles/koschei/common/tasks/main.yml

@@ -7,3 +7,8 @@
   - config
   - packages
   - yumrepos
+
+- name: Install common packages
+  package: name={{ item }} state=present
+  with_items:
+  - python-memcached