Added Grafana docs

Author: noctarius

docs/maintenance-operations/monitoring/accessing-grafana.md

@@ -3,4 +3,37 @@ title: "Accessing Grafana"
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+Simplyblock's control plane include a Prometheus and Grafana installation.
+
+Grafana retrieves metric data from Prometheus, including capacity, io statistics, the cluster event log. Additionally,
+Grafana is used for alerting via Slack or email.
+
+The standard retention period for metrics is 7 days. This, however, can be changed while creating a cluster.
+
+## How to access Grafana
+
+Grafana can be accessed through all management nodes via port 3000. It is recommended to set up a load balancer with
+session stickyness in front of the Grafana installation(s).
+
+```plain title="Grafana URLs"
+http://<MGMT_NODE_IP>:3000
+```
+
+To retrieve the endpoint address from the cluster itself, use the following command:
+
+```bash title="Retrieving the Grafana endpoint"
+sbcli cluster get <CLUSTER_ID> | grep grafana_endpoint
+```
+
+### Credentials
+
+The Grafana installation uses the cluster secret as its password for the user _admin_. To retrieve the cluster secret,
+the following command should be used:
+
+```bash title="Get the cluster secret"
+sbcli cluster get-secret <CLUSTER_ID>
+```
+
+**Credentials**<br/>
+Username: **admin**<br/>
+Password: **<CLUSTER_SECRET>**