Merge branch 'update_logging_docs' into 'master'

Update logging docs, add logcli example

See merge request openappstack/openappstack!354

docs/maintenance.md

@@ -5,30 +5,38 @@
 Logs from pods and containers can be read in different ways:
 
 * In the cluster filesystem at `/var/log/pods/` or `/var/logs/containers/`.
-* Using [kubectl logs](https://kubectl.docs.kubernetes.io/pages/container_debugging/container_logs.html).
-* Querying aggregated logs with grafana, see below.
+* Using [kubectl logs](https://kubernetes.io/docs/concepts/cluster-administration/logging)
+* Querying aggregated logs with Grafana, see below.
 
 ## Central log aggregation
 
-We use [promtail](https://github.com/grafana/loki/tree/master/docs/clients/promtail),
-[Loki](https://grafana.com/oss/loki/) and [grafana](https://grafana.com/) for
+We use [Promtail](https://grafana.com/docs/loki/latest/clients/promtail/),
+[Loki](https://grafana.com/oss/loki/) and [Grafana](https://grafana.com/) for
 easy access of aggregated logs.
-The [Loki documentation](https://github.com/grafana/loki#documentation) is a
-good starting point how this setup works, and the [Using Loki in Grafana](https://grafana.com/docs/grafana/latest/features/datasources/loki/)
-gets you started with querying your cluster logs with grafana.
+The [Loki documentation](https://grafana.com/docs/loki/latest/) is a
+good starting point how this setup works, and the [Using Loki in Grafana](https://grafana.com/docs/grafana/latest/datasources/loki)
+gets you started with querying your cluster logs with Grafana.
 
-You will find the loki grafana integration on your cluster at https://grafana.oas.example.org/explore
+You will find the Loki Grafana integration on your cluster at https://grafana.oas.example.org/explore
 together with some generic query examples.
 
 ### LogQL query examples
 
-Please also refer to the [LogQL documentation](https://github.com/grafana/loki/blob/master/docs/logql%2Emd).
+Please also refer to the [LogQL documentation](https://grafana.com/docs/loki/latest/logql).
 
+Query all aggregated logs (unfortunatly we can't find a better way of doing this
+since LogQL always expects a stream label to get queried):
 
-Query all apps for errors etc:
+    logcli query '{foo!="bar"}'
+
+Query all logs for a keyword:
+
+    logcli query '{foo!="bar"} |= "error"'
+
+Query all k8s apps for errors using a regular expression:
+
+    logcli query '{job=~".*"} |~ "error|fail|exception|fatal"'
 
-    {job=~".*"} |~ "error|fail|exception|fatal"
-    {job=~".*"} |= "level=error"
 
 #### Flux