Creating new user nodepool and transferring all existing workloads

Question

Hello community,

First, I am trying to replace a user nodepool and would like to know what's the detailed steps to transfer all workloads from previous nodepool to the new one. Many of AKS add-ons are also installed on that user nodepool as well! (e.g. csi driver, cloud manager, coredns ...)

Also, when creating a new deployment, is there a way to specify that the pods should be in the user pool not system pool? I have created a deployment and it was assigned to system pool instead of user pool

Thanks!

Answer 1

Hello @Kopl ,
There are multiple ways to transfer the workloads ,

1) one of the easiest way is:- Once you add the new node pool try to scale down the previous node pool - all the workloads will be automatically be moved to new node pool.

Please Note:- Above migration works ONLY If your workloads are controlled by deployment/Replicaset etc.

2) Second way:- Once you add the new nodepool , try to drain the old nodepool nodes by using below command:
kubectl drain NodeID - Once you run that command , you might get some warnings try to follow those warnings. (Try to run that command on all the nodes of old nodepool)
Once the drain is successful , all the workloads will be moved to new nodes.

3) Third way:- Once the new node pool gets added , you can try deleting the old nodepool - workloads will be automatically moved.

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Regarding your second question:
Yes ! If you observe carefully for all the nodes under system nodepool , there will be a label like : kubernetes.azure.com/mode=system
You can use the concept of taints to prevent application pods from being scheduled on system nodepool.

Take a look at the : https://learn.microsoft.com/en-us/azure/aks/use-system-pools?tabs=azure-cli#system-and-user-node-pools

Regards,
Shiva.