Back to lesson: Apply Observe, Narrow, Verify Under Time Pressure
Free lab · CKA Prep Program · Module 6: Troubleshooting
Break and fix
30 min hands-on · Advanced
Browser Kubernetes (Killercoda 1-node) or Play-with-Kubernetes; no local installs.
Two ways to do this lab: in your browser on Killercoda (free, no install), or on Play-with-Kubernetes as a free practice field. The Killercoda button opens in a new tab; this study page stays here. Killercoda runs one free scenario at a time: if you see a waiting queue, close other Killercoda tabs and wait a minute.
Objectives
- Diagnose a CrashLoopBackOff to its layer in under ten minutes
- Fix a broken Service selector using endpoints evidence
- Write the four-line incident record for each break
Step 1
CrashLoop drill
Deploy a pod with a bad command (or bad probe) and diagnose it with the observe-narrow-verify loop: describe, logs with previous, events sorted. Fix it, then write the incident record.
Step 2
Selector drill
Point a Service at labels that match nothing (`kubectl get endpoints` empty). Diagnose from endpoints first, fix the selector, curl to prove it. Record the rule: endpoints first, always.
Step 3
Timed round
Repeat both drills against the clock: ten minutes each, flag rule on. Record where the minutes actually went; that gap is the training target.
How to confirm it worked
- Both root causes found from evidence, not guesses
- Two four-line incident records written
- Timed round logged with minutes-per-step