r/jellyfin: Enable Prometheus metrics

Jellyfin can expose metrics in Prometheus format, but this functionality
is disabled by default.  To enable it, we must set `EnableMetrics` in
the configuration file.  This commit adds a template configuration file
that uses the `jellyfin_enable_metrics` Ansible variable to control this
value.

roles/jellyfin/tasks/deploy.yml

@@ -37,6 +37,28 @@
     state: directory
   tags:
   - datadir
+
+- name: ensure jellyfin configuration directory exists
+  file:
+    path: /var/lib/jellyfin/config
+    owner: jellyfin
+    group: jellyfin
+    mode: u=rwx,go=rx
+    state: directory
+  tags:
+  - config
+
+- name: ensure jellyfin system is configured
+  template:
+    src: system.xml.j2
+    dest: /var/lib/jellyfin/config/system.xml
+    owner: jellyfin
+    group: jellyfin
+    mode: u=rw,go=r
+  tags:
+  - config
+  notify:
+  - restart jellyfin
   
 - name: ensure jellyfin environment is configured
   template: