Day 7: Kubernetes Troubleshooting

Welcome to the final day of the KubeWeek Challenge!

Today, we will be focusing on Kubernetes troubleshooting, We’ll dive into using kubectl commands, analyzing logs, and debugging container images. These tools and techniques are essential for diagnosing and resolving issues in your Kubernetes environment.

Table of Contents

1. Key kubectl Commands for Troubleshooting
2. Analyzing Logs for Diagnostics
3. Debugging Container Images
4. Conclusion

1. Key kubectl Commands for Troubleshooting

kubectl is the primary command-line tool for interacting with Kubernetes clusters. Knowing how to use it effectively for troubleshooting can save time and prevent downtime.

Checking Cluster and Node Status:

1. Check Cluster Info:

kubectl cluster-info

2. Check Node Status:

kubectl get nodes

3. Check Pod Status:

kubectl get pods -o wide

4. Describe Resources:

kubectl describe pod <pod-name>

5. Check Events:

kubectl get events --sort-by=.metadata.creationTimestamp

Identifying Resource Usage:

1. Check Pod Resource Usage:

kubectl top pod

2. Check Node Resource Usage:

kubectl top node

3. Check Namespace Resource Usage:

kubectl top namespace

2. Analyzing Logs for Diagnostics

Logs are invaluable for identifying the root cause of issues. Kubernetes provides access to logs at various levels, from the entire cluster to individual containers.

Viewing Pod Logs:

1. View Logs of a Single Container:

kubectl logs <pod-name> -c <container-name>

2. Stream Logs in Real-Time:

kubectl logs -f <pod-name>

3. View Logs from Previous Instances:

kubectl logs <pod-name> --previous

4. View System Component Logs:

journalctl -u kubelet

Analyzing Application-Level Logs:

1. Filter Logs by Keywords:

kubectl logs <pod-name> | grep <keyword>

2. Analyze Logs Across Multiple Pods:

kubectl logs -l <label-selector>

3. Debugging Container Images

Container issues often stem from misconfigurations or bugs within the image. Kubernetes provides several tools to help debug these issues.

Start a Debugging Pod:

1. Launch a Pod with a Debugging Shell:

kubectl run -it --rm debug --image=busybox -- /bin/sh

2. Copy Files from a Container:

kubectl cp <pod-name>:/path/to/file /local/path

3. Inspect a Stuck Pod:

kubectl exec -it <pod-name> -- /bin/sh

4. Debug Using an Ephemeral Container:

kubectl debug <pod-name> --image=busybox

Common Debugging Techniques:

1. Check Environment Variables:

kubectl exec <pod-name> -- printenv

2. Test Network Connectivity:

kubectl exec <pod-name> -- curl <service-name>:<port>

3. Run Diagnostics Commands:

kubectl exec <pod-name> -- netstat -tuln

Conclusion

By mastering kubectl commands, analyzing logs, and debugging container images, We can quickly diagnose and resolve issues within our cluster. Whether we are handling a production outage or simply ensuring our applications are running smoothly.

#KubeWeek #Kubernetes #TrainWithShubham #DevOps #k8s