Klustered: Advanced Cluster Triage

Go beyond kubectl and develop a battle-tested methodology for diagnosing multi-layer outages. Each scenario highlights a different failure domain—nodes, networking, security, and host-level manipulation—so you can bring clusters back from the dead.

Learning Objectives

• Adopt a repeatable triage framework: validate symptoms, isolate the failing layer, and confirm the fix.
• Combine Kubernetes logs with host forensics (journalctl, systemctl, ps, lsof) when the API server is lying—or gone.
• Repair control-plane failures by dissecting static pod manifests, TLS assets, and etcd health.
• Detect malicious persistence (cron/systemd jobs, ld.so.preload, kubeconfig auth plugins) that reintroduce problems after a reboot.
• Harden clusters after recovery by applying network controls, auditing admission webhooks, and documenting runbooks.

Videos in This Path

1. Marino Wijay & John Anderson

Why it matters: Kubelet crashes and CNI misfires are the bread-and-butter incidents that escalate quickly. This episode establishes a systematic triage cadence.

What you’ll learn:

• Diagnose NodeNotReady states by correlating kubelet logs, CNI status, and certificate errors.
• Inspect static pod manifests and component arguments under /etc/kubernetes/manifests.
• Track down webhook failures and broken admission controllers that silently reject workloads.

Key takeaways:

• Trust but verify your cluster context and credentials before making changes.
• Pod lifecycle issues often stem from lower layers—container runtime, CNI, or certificates—not the workload itself.

Hands-on drill: Reproduce a NodeNotReady incident by breaking the CNI config in a test cluster, then repair it using the workflow demonstrated.

2. Hans Kristian Flaatten & Zach Wachtel

Why it matters: Slow control planes are harder than outright failures. This session shows how to hunt down etcd pain, I/O throttling, and sneaky persistence.

What you’ll learn:

• Profile control-plane latency and leader-election behaviour when etcd is under duress.
• Use low-level tools (crictl, journalctl, iostat) when kubectl no longer returns data.
• Discover malicious cron/systemd jobs reintroducing broken configs after each reboot.

Key takeaways:

• etcd health directly governs API responsiveness; treat disk I/O and quotas as first-class SLOs.
• Persistent host tasks can undo your fixes—eradicate them or they’ll respawn the outage.

Hands-on drill: Simulate etcd I/O starvation (e.g., tc or cgroup limits) and practice restoring health plus cleaning persistence hooks.

3. Alex Jones & Alistair Hey

Why it matters: Networking mysteries rarely announce themselves. This duel demonstrates how to peel back NodePorts, policies, and host firewalls.

What you’ll learn:

• Trace traffic with kubectl exec, iptables -t nat, and tc to find where packets die.
• Validate kube-controller-manager and kubelet configs when scheduling subtly fails.
• Guard yourself against sabotaged tooling (rogue aliases, modified kubeconfigs) that hinder troubleshooting.

Key takeaways:

• Multi-layer debugging beats guesswork—test from pod → node → service to pinpoint the break.
• Always confirm your tools haven’t been tampered with; even kubectl can be weaponized.

Hands-on drill: Inject latency with tc qdisc, observe service behaviour, then revert settings and record a runbook entry.

4. The Community vs. Rawkode

Why it matters: Security incidents often masquerade as outages. This group effort dissects a malicious kubeconfig helper and recovers the control plane.

What you’ll learn:

• Audit kubeconfig exec plugins to detect hostile authentication helpers.
• Use classic Linux tooling (ps, at, env) to uncover suspicious activity on nodes.
• Restore control-plane availability by editing static manifests and restarting kubelet safely.

Key takeaways:

• kubeconfig files are executable attack surfaces—treat them like code.
• Static pod manifests provide single points of failure; secure and monitor them rigorously.

Hands-on drill: Craft a harmless kubeconfig exec helper, document how it executes, then disable it using RBAC and config policies.

5. Klustered #11

Why it matters: The finale showcases deep Linux forensics—hidden processes, etcd DoS, and host firewalls—under extreme pressure.

What you’ll learn:

• Detect tampering techniques (ld.so.preload, rogue systemd units) that hide processes and binaries.
• Recover from etcd quota exhaustion and network lockouts using snapshots, compaction, and targeted iptables rules.
• Combine filesystem, network, and process evidence into a cohesive incident timeline.

Key takeaways:

• Complex outages demand patience, logs, and note-taking before touching anything.
• Hardened control planes require both Kubernetes and OS-level defenses (firewalls, file integrity, RBAC).

Hands-on drill: Build a lab where etcd hits its quota, practice compaction/defrag, then add iptables rules to lock down peer traffic.

Bonus Practice Scenarios

• Jetstack & CrashLoopBackoff — Chaos around admission webhooks and TLS.
• IBM & Nisum — Multi-team debugging of broken upgrades.
• Klustered Teams: Aerospike & Pixie Labs — Service mesh vs. DNS whodunit.
• Chainguard vs. Chainguard — Supply-chain sabotage meets cluster hardening.

After-Action Suggestions

1. Turn your notes into a written incident response playbook (symptom → hypothesis → command sequence).
2. Automate recurring diagnostics with kubectl debug profiles or Systemd/Ansible scripts.
3. Feed lessons learned into platform guardrails: enforce admission webhook health, lock down kubeconfig exec plugins, and monitor etcd quotas continuously.