Focused, hands-on problems for sharpening your DevOps and server-side skills. Some teach specific concepts while others mirror real-world scenarios. Every challenge includes hints, feedback, and automated solution checks.
node-02 is back from a kernel upgrade but still shows Ready,SchedulingDisabled, and the Pods that can only run on it are stuck in Pending. Bring the node back into service and get the workload running, without touching the workload itself.
A new intern learning about probes wrote a small Pod manifest. The exec command and the application are both correct, but the Pod never becomes Ready because one probe parameter is missing. Find it and add it.
A worker node dropped to NotReady and part of the workload went with it. The container runtime is fine and the control plane is healthy; the trail leads from kubectl symptoms down into systemd and the kubelet configuration. Diagnose the node and bring it back.
Every kubectl command against a kubeadm cluster fails, and the workload is still serving. With no API to query, the usual tools tell you nothing. Work from the node itself to find what broke and bring the control plane back.
The production "Calendar Todo" web application has been deployed in the prod namespace but all pods are stuck in Pending. Investigate the cluster, identify why the application cannot run, fix the underlying node issue, and verify the app is serving traffic on NodePort 31777.
A Deployment is stuck with Pods in ContainerCreating state because the required ConfigMap was not created. Fix the issue to make the application accessible.
A new service needs to run in your development environment, but the port it requires is already in use by another app that has to keep working. Diagnose the conflict, free the port without taking the other app down, and get both services running side by side - a realistic exercise in untangling local port conflicts.
A daemon exposes a Unix domain socket that every local user can talk to. Protect it so that only root and members of a dedicated group may connect - the same way Docker restricts access to /var/run/docker.sock.
A web application is deployed but the website is not accessible. Investigate and fix the issue.
A deployment is failing because the application cannot load its TLS certificate. Create the missing secret and mount it into the deployment so the Flask app can serve TLS traffic.
