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Kubernetes Logging

Kubernetes Logging

/var/log/containers ==> default log location on nodes. Last two log files are retained on the node.

In order to aggregate logs from varies sources like pods, containers , nodes, control plane and events we use fluentd and elastic search for searching and grafana for visualization.


Logging Architecture - Nodes:

  • Kubectl logs $POD_NAME ==> accessing pod logs
  • Kubectl logs $POD_NAME -c $CONTAINER_NAME ==> specific container inside a pod.
  • Kubectl logs $POD_NAME --all-containers
  • Kubectl logs $POD_NAME --all-containers --follow ==> real time logs
  • Kubectl logs --selector app=backend --all-containers

When an api server is down then in that case we cannot use kubectl get logs instead we can log in to a node and directly run 

  • docker logs $CONTAINER_NAME

What if docker is not available? 

  • tail -f /var/log/containers/$CONTAINER_NAME$CONTAINER_ID

Logging Architecture - Control Plane:

Get a list of control plane pods using a selector
  • kubectl get pods --namespace kube-system --selector tier=control-plane
  • kubectl logs --namespace kube-system $POD_NAME

Kubernetes Events:

Logs for resources defined in the cluster changes in resource state.
  • kubectl get events
  • kubectl describe $TYPE $NAME

Happy Learning😉

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