Skip to main content

Troubleshooting

Linux BPF CPU Profiling with kubectl on Microsoft Azure Kubernetes (AKS)

./flameget.sh --node "ip-10-40-33-102.ap-south-1.compute.internal" --pod "bad-deploy-6d5cc4d5f6-gvs6f" --container "bad-app" -t "60" -i "aimvector/ebpf-tools:azure.4.15.0.1061"

https://medium.com/@aimvec/linux-bpf-cpu-profiling-with-kubectl-on-kubernetes-8ca329297e5a

https://github.com/marcel-dempers/cpu-performance-analysis

Docker container CPU analysis with Linux BPF tools

image

https://learnk8s.io/troubleshooting-deployments

Questions​

Deep Dive Debugging​

  1. Pod stuck in CrashLoopBackOff, no logs, no errors.
    • How do you debug beyond kubectl logs and describe?
  2. A StatefulSet pod won’t reattach its PVC after a node crash.
    • How do you recover without recreating storage?
  3. Pods are Pending, Cluster Autoscaler won’t scale up.
    • Walk me through your top 3 debugging steps.
  4. NetworkPolicy blocks cross-namespace traffic.
    • How do you design least-privilege rules and test them safely?
  5. Service must connect to an external DB via VPN inside the cluster.
    • How do you architect it for HA + security?

Security + Architecture​

  1. Running a multi-tenant EKS cluster.
    • How do you isolate workloads with RBAC, quotas, and network segmentation?
  2. Kubelet keeps restarting on one node.
    • Where do you look first – systemd, container runtime, or cgroups?
  3. Critical pod got evicted due to node pressure.
    • Explain QoS classes and eviction policies.
  4. A rolling update caused downtime.
    • What went wrong in your readiness/startup probe or deployment config?
  5. Ingress Controller fails under load.
    • How do you debug and scale routing efficiently?

Performance + Reliability​

  1. Istio sidecar consumes more CPU than your app.
    • How do you profile and optimise mesh performance?
  2. etcd is slowing down control plane ops.
    • Root causes + how do you tune it safely?
  3. You must enforce images from a trusted internal registry only.
    • Gatekeeper, Kyverno, or custom Admission Webhook – what’s your move?
  4. Pods stuck in ContainerCreating forever.
    • CNI attach delay? OverlayFS corruption? Walk me through your root-cause process.
  5. Random DNS failures in Pods.
    • How do you debug CoreDNS, kube-proxy, and conntrack interactions?