ced4568andClaude Sonnet 5
28c925069b
content/root/root-10-kubernetes-troubleshooting-observability/m01-health-probes/: lesson (probe concepts) -> demonstration (reading kubectl describe pod Events for a probe failure) -> knowledge check -> guided exercise (write a readiness probe on paper) -> Launch Lab intro (rootnode-probe-port-mismatch) -> reflection (root cause + Real Ops prevention takeaway). 5 of 6 activities carry instructor notes (demo plan, misconceptions, timing, discussion questions, extensions). This is the reference implementation docs/COURSE_AUTHORING_STANDARD.md documents for all future RootNode lesson authoring. Co-Authored-By: Claude Sonnet 5 <[email protected]>
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Launch Lab: Stuck Not-Ready: The Probe Port Mismatch
Time to apply everything from this module against a real, running incident — not a diagram, an actual Deployment in your own disposable Lab environment.
What you're walking into
A deployment called api-gateway has been rolled out. The pods start, the container runs — but
the deployment never reaches Ready, and traffic isn't being routed to it. Somewhere on-call, an
alert is firing.
You now have everything you learned in this module to work with:
- The lesson told you what "stuck at 0/2 Ready with 0 restarts" actually means (a readiness problem, not a crash).
- The demonstration showed you exactly where to look for the explanation —
kubectl get pods, thenkubectl describe podand its Events section — and what a port-mismatch failure looks like in that output. - The guided exercise had you reason through what a correct probe definition looks like, which is exactly what you'll need to compare the broken one against.
Your task in this Lab
Diagnose why the pods are failing their readiness check, correct the probe configuration, and restore the deployment to fully Ready. Start with pod status and events, the same way you just practiced — read before you patch.
This Lab has its own in-context hints if you get stuck, revealed one at a time — use the concepts from this module first; reach for a hint only if you're genuinely stuck, not as the first move.
When the Lab confirms your fix, come back to this module to close it out with a short reflection on what actually caused this.
Instructor Notes
Classroom flow: if teaching this live, this is the natural point to have students launch their own Lab environment and work independently or in pairs, while you circulate. The Real-Time Classroom dashboard's help-request and progress views (see the instructor Curriculum view) show who's stuck without needing to walk around asking.
Approximate timing: 15-20 minutes for most students; some will resolve it in under 5 once the module's concepts have landed.
Common mistake to watch for: students jumping straight to kubectl logs here, which will
be unhelpful (nginx has nothing to say about a probe pointed at the wrong port) — this is a good
moment to reinforce the demonstration's point about reading Events first for this failure class.