Enable Unified Alerting and wire up with alertmanager

Grafana v8.2.0 added support for Prometheus's Alertmanager[1] which can be used with the Unified Alerting added in v8.0.0[2].

[1] https://github.com/grafana/grafana/releases/tag/v8.2.0 [2] https://grafana.com/blog/2021/06/08/grafana-8.0-unified-grafana-and-prometheus-alerts-live-streaming-new-visualizations-and-more/

roles/grafana/templates/datasources.yaml.j2

@@ -19,6 +19,8 @@ datasources:
   type: loki
   access: proxy
   url: http://localhost:3100
+  jsonData:
+    manageAlerts: false
 - name: Alertmanager
   type: alertmanager
   access: proxy