Single dashboards upd (#1593)

* dasbhoard: replace `null` datasources

null datasource value may confuse Grafana and make it drop panel query in some
versions.

* docker: bump grafana image version

* dashboards: add URL variable selector to vmagent dashboard

* dashboards: add new panel `Remote write connection saturation` to vmagent dashboard

* alerts: add new alert for `Remote write connection saturation` panel of vmagent dashboard

* dashboards: add "Logging rate" panel to vmagent dashboard

deployment/docker/alerts.yml

@@ -276,3 +276,16 @@ groups:
           summary: "Job \"{{ $labels.job }}\" on instance {{ $labels.instance }} fails to push to remote storage"
           description: "Vmagent fails to push data via remote write protocol to destination \"{{ $labels.url }}\"\n
             Ensure that destination is up and reachable."
+
+      - alert: RemoteWriteConnectionIsSaturated
+        expr: rate(vmagent_remotewrite_send_duration_seconds_total[5m]) > 0.9
+        for: 15m
+        labels:
+          severity: warning
+        annotations:
+          dashboard: "http://localhost:3000/d/G7Z9GzMGz?viewPanel=84&var-instance={{ $labels.instance }}"
+          summary: "Remote write connection from \"{{ $labels.job }}\" (instance {{ $labels.instance }}) to {{ $labels.url }} is saturated"
+          description: "The remote write connection between vmagent \"{{ $labels.job }}\" (instance {{ $labels.instance }}) and destination \"{{ $labels.url }}\"
+            is saturated by more than 90% and vmagent won't be able to keep up.\n
+            This usually means that `-remoteWrite.queues` command-line flag must be increased in order to increase
+            the number of connections per each remote storage."

deployment/docker/docker-compose.yml

@@ -17,7 +17,7 @@ services:
 
   grafana:
     container_name: grafana
-    image: grafana/grafana:8.0.0
+    image: grafana/grafana:8.1.2
     depends_on:
       - "vmselect"
     ports: