On AKS are System node pool the same as master node?
I know that with Azure AKS , master components are fully managed by the service. But I'm a little confused here when it comes to pick the node pools. I understand that there are two kind of pools system and user, where the user nodes pool offer hosting my application pods. I read on official documentation that System node pools serve the primary purpose of hosting critical system pods such as CoreDNS and tunnelfront. And i'm aware that we can only rely on system nodes to create and run our kubernetes cluster.
My question here, do they mean here by the system node the MASTER node ? If it is so, why then we have the option to not create the user nodes (worker node by analogy) ? because as we know -in on prem kubernetes solution- we cannot create a kubernetes cluster with master nodes only.
I'll appreciate any help
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System node pools in AKS does not contain Master nodes. Master nodes in AKS are 100% managed by Azure and are outside your VNet. A system node pool contains worker nodes on which AKS automatically assigns the label kubernetes.azure.com/mode: system, that's about it. AKS then use that label to deploy critical pod like tunnelfront, which is use to create a secure communication from your nodes to the control plane. You need at least 1 system node pool per cluster and they have the following restrictions :
- System pools osType must be Linux.
- System pools must contain at least one node, and user node pools may contain zero or more nodes.
- System node pools require a VM SKU of at least 2 vCPUs and 4GB memory. But burstable-VM(B series) is not recommended.
System node pools must support at least 30 pods as described by the minimum and maximum value formula for pods.
1: https://docs.microsoft.com/en-us/azure/aks/use-system-pools#system-and-user-node-pools