Questions about taint based eviction

[Guang Ya Liu]

Hi,

I have some question for taint based eviction. With taint based eviction, when I shutdown a node or just kill kubelet on the node, node controller will add taint "node.alpha.kubernetes.io/unreachable:NoExecute" to the node, but I found that the pod on the node was not get evicted but keeps running, and I also found that the controller manager was already putting the node to taint queue as following in controller manager:

Node xxx is unresponsive as of 2017-11-14 10:14:07.675311698 +0000 UTC. Adding it to the Taint queue.

But There is no eviction was triggered on that node and the pods keeps on running. 

I was using Kubernetes 1.8.2 and 1.8.3, both does not work, but I check the code and found no logic error, am I missing anything for this?

/cc @gmarek

Thanks,

Guangya

[edison xiang]

Hi Guangya,

        Do you deploy DaemonSet pods in that Node?

DaemonSet pods are created with NoExecute tolerations for the following taints with no tolerationSeconds:

• node.alpha.kubernetes.io/unreachable
  
• node.kubernetes.io/not-ready 
  

This ensures that DaemonSet pods are never evicted due to these problems, which matches the behavior when this feature is disabled

        If not, it is better to set tolerationSeconds when setting tolerations,

        Because if not set tolerationSeconds, pods are never evicted like DaemonSet pods.

tolerations:

- key: "node.alpha.kubernetes.io/unreachable"

  operator: "Exists"

  effect: "NoExecute"

  tolerationSeconds: 300

        I am not sure whether it will be helpful to you.

        

        Refer: https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/

Best Regards,

        Edison Xiang 

[Guang Ya Liu]

Thanks Edison, I was not using daemonset but deployment. Seems to be an env issue, after re-install, it is working well. thanks.

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