EKS Cluster
EKS clusters are composed of the following main components—a control plane and worker nodes. Each cluster runs in its own, fully managed Virtual Private Cloud (VPC).
The control plane is composed of three master nodes, each running in a different AZ to ensure AWS high availability. Incoming traffic directed to the Kubernetes API passes through the AWS network load balancer (NLB).
Worker nodes run on Amazon EC2 instances located in a VPC. EKS provides managed node groups with automated lifecycle management. This lets users automatically create, update, or shut down nodes with one operation. EKS uses Amazon’s latest Linux AMIs optimised for use with EKS. When nodes are terminated, EKS gracefully drains them to make sure there is no interruption of service.
High Availability
Amazon EKS runs and scales the Kubernetes control plane across multiple AWS Availability Zones to ensure high availability. Amazon EKS automatically scales control plane instances based on load, detects and replaces unhealthy control plane instances, and automatically patches the control plane.
The EKS cluster consists of EC2 instances deployed in multiple availability zones within the region. Each instance has replicas of the services and nodes which exist across all the EC2 instances.
Each zone or instance has an active pod listening to other instances. In case of a failure of any instance, the active pod ensures seamless functioning of the application by activating the nodes from any other working cluster.