When
you create an AKS cluster, a control plane is automatically created
and configured. This control plane is provided as a managed Azure
resource abstracted from the user. There's no cost for the control
plane, only the nodes that are part of the AKS cluster.
The
control plane includes the following core Kubernetes components:
- kube-apiserver - The API server is how the underlying Kubernetes APIs are exposed. This component provides the interaction for management tools, such as
kubectlor the Kubernetes dashboard.
- etcd - To maintain the state of your Kubernetes cluster and configuration, the highly available etcd is a key value store within Kubernetes.
- kube-scheduler - When you create or scale applications, the Scheduler determines what nodes can run the workload and starts them.
- kube-controller-manager - The Controller Manager oversees a number of smaller Controllers that perform actions such as replicating pods and handling node operations.
AKS
provides a single-tenant control plane, with a dedicated API server,
Scheduler, etc. You define the number and size of the nodes, and the
Azure platform configures the secure communication between the
control plane and nodes. Interaction with the control plane occurs
through Kubernetes APIs, such as
kubectl or
the Kubernetes dashboard.
This
managed control plane means that you don't need to configure
components like a highly available etcd store,
but it also means that you can't access the control plane directly.
Upgrades to Kubernetes are orchestrated through the Azure CLI or
Azure portal, which upgrades the control plane and then the nodes. To
troubleshoot possible issues, you can review the control plane logs
through Azure Monitor logs.
If
you need to configure the control plane in a particular way or need
direct access to it, you can deploy your own Kubernetes cluster
using aks-engine.
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