CKA-Troubleshooting 출제비중 30%

- Evaluate cluster and node logging

Control Plane nodes

• /var/log/kube-apiserver.log - API Server, responsible for serving the API
• /var/log/kube-scheduler.log - Scheduler, responsible for making scheduling decisions
• /var/log/kube-controller-manager.log - a component that runs most Kubernetes built-in controllers, with the notable exception of scheduling (the kube-scheduler handles scheduling).

Worker Nodes

• /var/log/kubelet.log - logs from the kubelet, responsible for running containers on the node
• /var/log/kube-proxy.log - logs from kube-proxy, which is responsible for directing traffic to Service endpoints

- Understand how to monitor applications

Debugging Pods

kubectl describe pods ${POD_NAME}

- Manage container stdout & stderr logs

 

A container runtime handles and redirects any output generated to a containerized application's stdout and stderr streams. Different container runtimes implement this in different ways; however, the integration with the kubelet is standardized as the CRI logging format.

By default, if a container restarts, the kubelet keeps one terminated container with its logs. If a pod is evicted from the node, all corresponding containers are also evicted, along with their logs.

The kubelet makes logs available to clients via a special feature of the Kubernetes API. The usual way to access this is by running kubectl logs

 

- Troubleshoot application failure

- Troubleshoot cluster component failure

- Troubleshoot networking

 

트러블슈팅에 대한 부분은 document에 자세한 내용은 없기도 하고 사실문제를 해결하는 방법은 상황에 따라 다르기 때문에 증상 및 원인을 파악하는 능력을 길러야 하는 방법뿐이듯 한다.