Using Grafana and Loki to Manage Kubernetes Logs

• Grafana
• Loki
• Kubernetes
• logs
• k8s
• 8s-logs
• advanced

Scaleway Kubernetes Kapsule is not delivered with an embedded logging feature.
In this tutorial, you will learn how to use Loki and Grafana to collect your Kubernetes logs on a Kapsule cluster.

Loki is a log aggregation system inspired by Prometheus. It is easy to operate, as it does not index the content of the Kubernetes logs but sets labels for log streams. The metadata you use (object labels) can be used in Loki for scraping kubernetes logs. If you use Grafana for metrics, Loki will allow you to have a single point of management for both logging and monitoring.

1. Add the Grafana repository to Helm and update it.

   helm repo add grafana https://grafana.github.io/helm-charts
   helm repo update
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   Which returns:

   "grafana" has been added to your repositories
   Hang tight while we grab the latest from your chart repositories...
   ...Successfully got an update from the "loki" chart repository
   ...Successfully got an update from the "grafana" chart repository
   Update Complete. ⎈Happy Helming!⎈
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2. Install all the stack in a Kubernetes dedicated namespace named loki-stack, using Helm. It must be deployed to your cluster and persistence must be enabled (allow Helm to create a Scaleway block device and attach it to the Loki pod to store its data) using a Kubernetes Persistent Volumes to survive a pod re-schedule:

   helm install loki-stack grafana/loki-stack \
                                   --create-namespace \
                                   --namespace loki-stack \
                                   --set promtail.enabled=true,loki.persistence.enabled=true,loki.persistence.size=100Gi
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   It will use Kapsule’s default storage class, scw-bsdd, to create block volumes using Scaleway Block Storage.

   Important:

   You must enter a size for the persistent volume that fits the amount of volume your deployment will create.

   Note:

   If you plan to use Loki on a production system, make sure that you set up a retention period to avoid filling the filesystems. Use these parameters if you want to enable a 30 days retention (logs older than 30 days will be deleted), for example.

   • config.table_manager.retention_deletes_enabled : true
   • config.table_manager.retention_period: 720h

3. Install Grafana in the loki-stack namespace with Helm. Enable persistance to make sure Grafana to remains stable in the event of a re-schedule.

   • persistence.enabled: true
   • persistence.type: pvc
   • persistence.size: 10Gi

   helm install loki-grafana grafana/grafana \
                                 --set persistence.enabled=true,persistence.type=pvc,persistence.size=10Gi \
                                 --namespace=loki-stack
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   You can check if the block devices were correctly created by Kubernetes:

   $ kubectl get pv,pvc -n loki-stack
   
   NAME                                                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                             STORAGECLASS   REASON   AGE
   persistentvolume/pvc-88038939-24a5-4383-abe8-f3aab97b7ce7   10Gi       RWO            Delete           Bound    loki-stack/loki-grafana           scw-bssd                18s
   persistentvolume/pvc-c6fce993-a73d-4423-9464-7c10ab009062   100Gi      RWO            Delete           Bound    loki-stack/storage-loki-stack-0   scw-bssd                4m30s
   
   NAME                                         STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
   persistentvolumeclaim/loki-grafana           Bound    pvc-88038939-24a5-4383-abe8-f3aab97b7ce7   10Gi       RWO            scw-bssd       19s
   persistentvolumeclaim/storage-loki-stack-0   Bound    pvc-c6fce993-a73d-4423-9464-7c10ab009062   100Gi      RWO            scw-bssd       5m3s
   

4. Check if the pods are correctly running.

   $ kubectl get pods -n loki-stack
   
   NAME                            READY   STATUS    RESTARTS   AGE
   loki-grafana-67994589cc-7jq4t   0/1     Running   0          74s
   loki-stack-0                    1/1     Running   0          5m58s
   loki-stack-promtail-dtf5v       1/1     Running   0          5m42s
   

5. Get the admin password.

   kubectl get secret --namespace loki-stack loki-grafana -o jsonpath="{.data.admin-password}" | base64 --decode ; echo
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6. Configure a port-forward to reach Grafana from your web browser:

   $ kubectl port-forward --namespace loki-stack service/loki-grafana 3000:80
   Forwarding from 127.0.0.1:3000 -> 3000
   Forwarding from [::1]:3000 -> 3000
   

7. Access http://localhost:3000 to reach the Grafana interface. Log in using the admin user and the password you got above.

   

   

8. Click Configuration > Data Sources in the side menu.

9. Click + Add Data Source.

10. Select Loki.

11. Add the Loki source to Grafana (http://loki-stack.loki-stack:3100).

    

    

12. Check you can access your logs using the explore tab in Grafana:

You now have a Loki stack up and running. All your pod’s logs will be stored in Loki and you will be able to view and query your kubernetes logs in Grafana. Please refer to the Grafana documentation here, if you want to learn more about querying the Loki data source.