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Extra Question 1 | Find Pods first to be terminated

 

Check all available Pods in the Namespace project-c13 and find the names of those that would probably be terminated first if the nodes run out of resources (cpu or memory) to schedule all Pods. Write the Pod names into /opt/course/e1/pods-not-stable.txt.

 

Answer:

When available cpu or memory resources on the nodes reach their limit, Kubernetes will look for Pods that are using more resources than they requested. These will be the first candidates for termination. If some Pods containers have no resource requests/limits set, then by default those are considered to use more than requested.

Kubernetes assigns Quality of Service classes to Pods based on the defined resources and limits, read more here: https://kubernetes.io/docs/tasks/configure-pod-container/quality-service-pod

Hence we should look for Pods without resource requests defined, we can do this with a manual approach:

Or we do:

We see that the Pods of Deployment c13-3cc-runner-heavy don't have any resources requests specified. Hence our answer would be:

To automate this process you could use jsonpath like this:

This lists all Pod names and their requests/limits, hence we see the three Pods without those defined.

Or we look for the Quality of Service classes:

Here we see three with BestEffort, which Pods get that don't have any memory or cpu limits or requests defined.

A good practice is to always set resource requests and limits. If you don't know the values your containers should have you can find this out using metric tools like Prometheus. You can also use kubectl top pod or even kubectl exec into the container and use top and similar tools.

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