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IBM·Software Engineer·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

IBM DevSecOps round that was pretty much a deep dive into Kubernetes troubleshooting. One question, lots of expected follow-up, felt more like a technical screen than a full panel.

Questions Asked (1)

Q1

A Kubernetes pod running a JDBC service is stuck in CrashLoopBackOff. Walk me through how you'd diagnose and fix it.

Root Cause AnalysisSystem DesignTechnical Trade-offs
Author's notes

This one has a lot of surface area and I think I handled the first layer fine (kubectl describe, checking events, exit codes) but fumbled a bit when they pushed on the JDBC-specific angle.

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AI HintsAI Generated

Suggested Approach

Start by systematically gathering information from the pod's logs, events, and configuration to identify the root cause of the crash. Then, based on the findings, apply targeted fixes and verify the pod recovers. Emphasize a methodical, evidence-based approach rather than jumping to conclusions.

Pro tip: Always check the previous container's logs with `kubectl logs --previous` to see the crash output, and inspect the pod's events with `kubectl describe pod` for clues like OOMKilled or liveness probe failures.

1. Gather Information

Use `kubectl describe pod <pod-name>` to check events, state, and restart count. Retrieve logs from the current and previous container instances with `kubectl logs <pod-name>` and `kubectl logs <pod-name> --previous`.

2. Identify the Failure Mode

Analyze logs and events to determine if the crash is due to application errors (e.g., JDBC connection failures), resource constraints (OOMKilled), configuration issues, or liveness probe failures.

3. Check Dependencies and Configuration

Verify that the database is reachable, credentials are correct, and environment variables or ConfigMaps/Secrets are properly set. Test connectivity from within the cluster if needed.

4. Apply Fix and Validate

Based on the root cause, adjust the deployment (e.g., fix connection string, increase memory limits, adjust probe timings) and redeploy. Monitor the pod to ensure it reaches Running state and stays healthy.

5. Prevent Recurrence

Consider implementing readiness/liveness probes, resource requests/limits, and proper logging to catch issues early. Document the incident and update runbooks.

Key Points to Mention

  • Use of kubectl commands: describe, logs, exec, get events
  • Common causes: database connectivity, authentication failures, missing environment variables, resource limits (OOMKilled), liveness probe misconfiguration
  • Importance of checking previous container logs for crash details
  • Verifying network policies and service endpoints for database access
  • Adjusting Kubernetes resource requests/limits and probe settings
  • Implementing robust health checks and monitoring to prevent future occurrences

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.