A more detailed description of Azure AKS architecture with examples:
- Control Plane: The Kubernetes control plane is responsible for managing the state of the cluster and providing the API server, etcd, kube-scheduler, and kube-controller-manager components. In AKS, the control plane is managed by Azure and is not directly accessible to customers. The control plane components run in a separate set of VMs, which are automatically provisioned and managed by Azure.
- Node Pools: A node pool is a group of virtual machines (VMs) that run the Kubernetes nodes. Each node pool can have different characteristics, such as size, operating system, and hardware type. AKS supports multiple node pools, allowing customers to customize the resources and settings for different workloads. For example, you could create one node pool with larger VMs for running memory-intensive workloads, and another node pool with smaller VMs for running CPU-intensive workloads.
- Virtual Nodes: AKS supports Virtual Nodes, which are AKS-managed containers that can automatically scale and provide additional capacity for running Kubernetes pods. Virtual Nodes run on Azure Container Instances (ACI) and can be used to handle short-term or bursty workloads. For example, you could configure a Kubernetes deployment to use Virtual Nodes for handling spikes in traffic, while using traditional VM-based nodes for steady-state workloads.
- Networking: AKS uses Azure Virtual Network (VNet) to provide network connectivity to the Kubernetes cluster. The VNet is used to isolate the cluster from other resources in the Azure environment and to provide secure communication between the nodes and the control plane. AKS also supports integration with Azure Load Balancer and Azure Application Gateway for load balancing and routing traffic to the Kubernetes services. For example, you could use Azure Load Balancer to distribute traffic across multiple instances of a Kubernetes service, ensuring high availability and scalability.
- Storage: AKS provides integration with Azure storage services such as Azure Disk and Azure Files to provide persistent storage for Kubernetes workloads. AKS also supports third-party storage providers through the Container Storage Interface (CSI). For example, you could use Azure Disk to provide persistent storage for a stateful application running in a Kubernetes pod, ensuring that data is preserved even if the pod is restarted or moved to another node.
- Container Registry: AKS supports integration with Azure Container Registry (ACR) to store and manage container images used in the Kubernetes workloads. ACR provides a private and secure registry for storing container images and supports features such as geo-replication, security scanning, and RBAC (Role-Based Access Control). For example, you could use ACR to store container images for your Kubernetes application, ensuring that they are secure and available for deployment across multiple AKS clusters.
AKS architecture is designed to provide a highly available, scalable, and secure Kubernetes cluster that can be easily managed and integrated with other Azure services. By using AKS, customers can focus on developing and deploying their Kubernetes applications, while leaving the underlying infrastructure management to Azure.
