Can kube-system pods start on "worker" nodes?

[Yakov Sobolev]

With the master set to unschedulable, do you know what happens if one of the pods already running on the master goes down? 

Have you seen those system-type pods come back up? 

It is OK to run these pods on nodes and not just the master;  reference https://kubernetes.io/docs/concepts/overview/components/) excerpt:

"...Master components can be run on any machine in the cluster. However, for simplicity, set up scripts typically start all master components on the same machine, and do not run user containers on this machine.."

 

[Robert Bailey]

How are the master components running? Some deployments use static pods on the master which mean that they can never be relocated to a different machine. If you are running them as pods in the cluster (i.e. via self-hosting) then your deployment tool has likely put in the correct tolerations so that they can continue to run on the master. 

In what cases would you set the master to be unschedulable (rather than using taints)?

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[Yakov Sobolev]

Thanks Robert.

How can I see what process launches my kube-system pods?

Our cluster is running on VMs.

kublet starts all components

[Robert Bailey]

On Fri, Sep 14, 2018 at 12:59 PM Yakov Sobolev <ysob...@ashland.edu> wrote:

Thanks Robert.

How

 

can I see what process launches my kube-system pods?

I was asking what deployment tool you used to create the cluster. They are opinionated about how the control plane is managed and configured. 

 

Our cluster is running on VMs.

kublet starts all components

How does the kubelet know which pods to run? Are they assigned by the scheduler and the kubelet is registered into a cluster? Does the kubelet read them from the local filesystem (/etc/kubelet/manifests)? Or from a URL?

 

On Friday, September 14, 2018 at 2:28:10 PM UTC-4, Yakov Sobolev wrote:

With the master set to unschedulable, do you know what happens if one of the pods already running on the master goes down? 

Have you seen those system-type pods come back up? 

It is OK to run these pods on nodes and not just the master;  reference https://kubernetes.io/docs/concepts/overview/components/) excerpt:

"...Master components can be run on any machine in the cluster. However, for simplicity, set up scripts typically start all master components on the same machine, and do not run user containers on this machine.."

 

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