How do you troubleshoot Stateful workloads in k8s when it fails?

When troubleshooting stateful workloads in Kubernetes (K8s) that have failed, it's essential to follow a systematic approach. Here's a guide to effectively troubleshoot such issues.

Steps to Troubleshoot Stateful Workloads

1. Check Pod Status: Use the command kubectl get pods to see the status of your stateful pods. Look for any pods that are in a 'CrashLoopBackOff' state.
2. Inspect Pod Logs: Use kubectl logs pod-name to look at the logs of the failing pod. This may give insight into any application-level errors.
3. Describe the Pod: Run kubectl describe pod pod-name to see detailed information about the pod, including events that might indicate problems.
4. Check Persistent Volumes: Ensure that the Persistent Volume Claims (PVCs) are properly bound. Check with kubectl get pvc.
5. Examine Resource Limits: Review whether the pod has sufficient CPU and memory resources by checking the resource limits defined in your deployment.
6. Validate Configurations: Double-check the configuration settings such as environment variables, secrets, and config maps that are fed into your application.
7. Rolling Back if Necessary: If the stateful application has a history of stable releases, consider rolling back to the previous stable configuration.

Example Scenario

        // Check all pods status
        kubectl get pods

        // View logs for a specific pod
        kubectl logs my-stateful-pod-0

        // Describe a specific pod to find issues
        kubectl describe pod my-stateful-pod-0