Scheduling, probes, workloads and the failure modes that come with them.
3 items at advanced level · all topics
What happens if an Auto Scaling instance never becomes healthy?
Auto Scaling terminates and replaces an instance that never passes health checks, which is fine once and expensive in a loop. How long you burn depends on the grace period, the check thresholds, and which health check type the group is actually using. The fix is working out why it's unhealthy: usually startup config, a wrong health endpoint, or a grace period shorter than boot time.
You use GitOps and someone changes Kubernetes manually. Git still has the old config. What happens?
You get configuration drift: Git says one thing, the cluster says another. What happens next depends on whether the controller self-heals or just reports it. Either way the manual change is temporary, and the fix is to put the intended change into Git, not to argue with the controller.
Argo CD keeps reverting your emergency production change. Why, and what should you do?
Self-heal is doing exactly what it was configured to do: pulling the cluster back to what Git says. During an incident, mitigate through something the controller doesn't manage, then get the real change into Git fast rather than fighting reconciliation head on.