Add Libvirt Prometheus exporter

This does not work as this functionality is built out of the Debian
packages. Hopefully it will be enabled one day...

roles/pvc/tasks/libvirt/main.yml

@@ -14,6 +14,15 @@
   retries: 5
   until: apt_res is success
 
+- name: install Prometheus libvirt exporter if enabled
+  apt:
+    name:
+      - prometheus-libvirt-exporter
+  register: apt_res
+  retries: 5
+  until: apt_res is success
+  when: enable_prometheus_exporters is defined and enable_prometheus_exporters
+
 - name: add libvirt user to ceph group
   user:
     name: libvirt-qemu

roles/pvc/templates/zookeeper/zoo.cfg.j2

@@ -19,9 +19,10 @@ maxClientCnxns=200
 autopurge.snapRetainCount=3
 autopurge.purgeInterval=1
 
-# Enable Prometheus metrics
-metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
-metricsProvider.httpPort=9181
+# Enable Prometheus metrics (someday, but not today under Debian 12 or less)
+#metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
+#metricsProvider.httpPort=9181
+#metricsProvider.exportJvmInfo=true
 
 # Listen on port 2181 on the cluster IP
 clientPort=2181