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For Kube-Proxy and Services, are they stateful?

Hi, for Kube-Proxy, CoreDNS, Services (Cluster IP, NodePort etc), and Endpoint, are they stateful (i.e. with persistent data)? Thank you.

1 Answers

Hi apccheng. I’m not sure I understand your question… Can you provide more detail? However, I’ll try and answer based on what I think you’re asking…

Kube-proxy creates local IPTABLES or IPVS rules that are stored locally on nodes

CoreDNS stores DNS mapping for service discovery etc in the cluster’s persistent store. The same goes for Services and Endpoint objects – they’re part of the clusters state which is stored in etcd the cluster’s store.

Hope that help.

ipccheng

Hi Nigel, at the beginning of the course you have mentioned etcd is the only stateful components in the Control Plane, so my understanding is Daemonset and STS are stateless. That’s why I’d like to know whether the other components are stateful (with persistant store) or not. I believe your reply has answered my question. Thank you!

nigelpoulton

OK I understand… The control plane is made up of things like: – The API server – the cluster store (etcd) – Controllers – The scheduler The only stateful component of that is the cluster store (etcd). Things like DaemonSets and Stateful Sets are not part of the control plane in that sense. They’re objects on the cluster that are implemented by the control plane, and their configurations are stored in etcd. So even a stateless Pod will have its configuration persisted to etcd. I think the important thing to understand this is that when we refer to the control plane, we’re referring to the main processes that run the cluster and are implemented by default when we install a cluster. Anything that we add later (Pods, Deployments, StatefulSets…) are not part of the control plane. They’re implemented and managed by the control plane, but they don’t form part of the control plane. Hope that helps.

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