Pods Log Monitoring

Pod logs are picked up by the Logging Operator and stored in Loki. The Rancher catalog provides three applications for this:

• Logging Subscriber (logging-subscriber) - Flow + Output pair, used by the Logging Operator, that monitors the Pods you select using labels and pushes their logs into Loki
• Loki (loki) - Logs aggregation
• Grafana (grafana) - Logs and metrics visualisation connected to Loki

InstallationCopy Anchor Link

If you are not already logged in, log in to rancher.cloud.e-infra.cz, see Rancher section.

1. Install GrafanaCopy Anchor Link

Pick grafana under Apps → Charts → cerit-sc and enter the URL prefix and the admin password in the form. The instance is then reachable at https://<prefix>.<your_namespace>.dyn.cloud.e-infra.cz. The other fields can stay at their defaults.

The installation of Grafana itself is described in detail in Grafana; it does not need Loki to be installed first — you connect them in the last step.

2. Install LokiCopy Anchor Link

1. In Rancher, go to Apps → Charts, filter charts to cerit-sc and pick loki.

2. Ensure you have selected your namespace, name the release loki and click Install. The install form offers no options — everything is preconfigured for this platform.

3. Install Logging SubscriberCopy Anchor Link

1. In Rancher, go to Apps → Charts, filter charts to cerit-sc and pick logging-subscriber.

2. Find the labels of the Pods of the application you want to watch. In Rancher open Workloads → Pods, select one Pod of your application and note its labels, or run:

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   kubectl -n <your_namespace> get pods --show-labels

3. Select the same namespace as the application you are watching and fill in the form:

How to configure the Grafana Loki Endpoint:

4. Click Install and check that the two resources appeared in the namespace:

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   kubectl -n <your_namespace> get flow,output

Configure GrafanaCopy Anchor Link

All 3 components should be now installed. It’s time to configure Grafana to connect to Loki.

Connect Grafana to LokiCopy Anchor Link

1. Log in as admin with the password from the form, then add Loki as a data source: Connections → Data sources → Add new connection → Loki, and set:

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   URL  http://loki-gateway:80                                     # Loki in the same namespace as Grafana
   URL  http://loki-gateway.<loki_namespace>.svc.cluster.local:80  # Loki in another namespace

   Custom Headers and authentication are not needed — the Loki is configured to accepts anonymous traffic inside the cluster. Finish with Save & test, which should report a successful connection.

Visualize the Logs in GrafanaCopy Anchor Link

1. Open Explore, select the Loki data source and switch to the Labels browser to see which labels actually arrived. Use those names in your queries — the labels you entered under Match Pod Labels are usually among them.

2. Query the logs (LogQL):

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   {app="my-application"}                               # all lines of the matched Pods
   {app="my-application"} |= "error"                    # only lines containing "error"
   {app="my-application"} != "DEBUG"                    # skip debug lines
   sum(count_over_time({app="my-application"} [1m]))    # lines per minute, as a graph

3. To turn a query into a panel, create a dashboard, Add → Visualization, pick the Loki data source and paste the query (the Builder helps you assemble it, Code accepts it as written above). Pick a visualisation — a log panel for raw lines, a bar/line graph for a metric query such as the last one — then Save the dashboard.

No dashboard is provisioned with the Grafana of this catalog — you can build the panels you need, or import one from grafana.com/dashboards that matches your data source.

CleanupCopy Anchor Link

Delete the applications under Apps → Installed Apps in any order. Deleting the logging-subscriber removes its Flow and Output, so the logs stop immediately; deleting Loki removes the stored logs together with its PVC.