What Are the Different Steps to Start EKS?

EKS stands for Elastic Kubernetes Service, which is an Amazon offering that helps in running the Kubernetes on AWS without requiring the user to maintain their own Kubernetes control plane. It is a fully managed service by Amazon.

Kubernetes is an open-source system that helps in the process of automatic deployment, scaling, and managing containerized applications.

Amazon EKS helps run Kubernetes control plane instances over multiple Availability Zones which makes sure that they are highly available. Amazon EKS automatically detects and replaces control plane instances that are unhealthy, as well as provisioning automated version upgrades and patching for the unhealthy control planes.

Amazon EKS can be integrated with other Amazon service in order to provide scalability and security for user applications, and some of the services have been listed below:

1. Authentication is served by IAM.
2. Isolation is served by Amazon VPC.
3. Amazon ECR for container images.
4. Elastic Load Balancing service to distribute the load.

Amazon EKS helps run up-to-date version of the open-source Kubernetes software, thereby allowing the user to use all the existing plugins and tooling which is availability in the Kubernetes community. Applications that run on Amazon EKS are completely compatible with applications which run on other standard Kubernetes environment, be it running in on premise data centres or in public clouds. This indicates that the user can migrate to other standard Kubernetes application very easily without modifying any code.

Amazon EKS Control Plane Architecture

Amazon EKS runs along with a single tenant Kubernetes control plane for every cluster. This control pane infrastructure can’t be shared with other clusters or AWS accounts. The control plane consists of a minimum of two API server nodes and three ‘etcd’ nodes which run across three Availability Zones which is present in a Region.

Amazon EKS detects and replaces unhealthy control plane instances automatically, and restarts them over these Availability Zones within the Region as and when required. Amazon EKS makes good use of the AWS Region architecture so as to provide high-availability. Due to all this, Amazon EKS offers SLA for API server endpoint availability.

Amazon EKS makes use of Amazon VPC network policies to restrict the traffic that flows between the components of the control plane and the single cluster. The components of the control plane for the cluster won’t be able to view or receive any communication from other clusters or AWS accounts, the only exception being an authorized Kubernetes RBAC policy.

Such security and high-availability configuration make Amazon EKS highly reliable, thereby making it suitable to be used in many production workloads too.

Working of Amazon EKS

The below images show how Amazon EKS works:

Image credit: aws.amazon.com

Steps to start Amazon EKS

Following are the steps to start Amazon EKS:

1. Create an Amazon EKS cluster with the AWS Management Console or AWS CLI or with one of the AWS SDKs.
2. Launch the worker node which registers the Amazon EKS cluster.
3. An AWS CloudFormation template can be provisioned that helps configure the nodes automatically.
4. When the cluster is ready, the user can configure it with the Kubernetes tools which is required for their application to communicate with their cluster.
5. This Amazon EKS cluster can be used to deploy and manage applications in the same manner as one would do with any other Kubernetes environment.

A Kubernetes cluster can be created in two ways:

1. With eksctl: This can be used to install the resources which are required to begin working with Amazon EKS ‘eksctl’. The ‘eksctl’ is a simple command line utility that can be used to create and manage Kubernetes cluster on Amazon EKS. This is considered to be one of the quickest and the simplest methods of creating a cluster with Amazon EKS.
2. With AWS Management Console: This method can be used to create the resources required to start working with Amazon EKS with the help of AWS Management Console. In this method, the user has to manually create every resource in the Amazon EKS or AWS CloudFormation console. This is considered as a much complicated and time-consuming method of creating and working with Amazon EKS.

Components of Amazon EKS Cluster

An Amazon EKS cluster consists of two major components. They have been discussed below:

Amazon EKS Control Plane

This consists of control plane nodes which are used to run Kubernetes software, which includes ‘etcd’ and the Kubernetes API server. This plane works with the account that is managed by AWS and the Kubernetes API is exposed to the outside through an Amazon EKS endpoint which is associated with the cluster user.

Every Amazon EKS cluster control plane is unique and consists of a single-tenant. It runs its own set of Amazon EC2 instances. The data which is stored with the help of ‘etcd’ nodes and the respective Amazon EBS volumes is in the encrypted form. Hence Amazon EKS uses master encryption keys which help in generating volume encryptions keys that are in turn managed by Amazon EKS service.

The cluster control plane has the ability to work across multiple Availability Zones and with the front-end through an Elastic Load Balancing Network Load Balancer. Amazon EKS can also be used to provide elastic network interfaces to the user’s VPC subnets thereby facilitating connectivity from the control plane instances to the worker nodes, so as to support ‘kubectl exec’, ‘logs’, and ‘proxy’ data flows.

Amazon EKS worker nodes registered with the control plane:

Worker machines in Kubernetes are known as worker nodes. Amazon EKS worker nodes can be run in the user’s AWS account to help connect the cluster’s control plane through an API server endpoint. This will also have a certificate file which is created for the server. Amazon EKS worker nodes can be understood as standard Amazon EC2 instances, and they are charged based on how EC2 instances are normally charged.

As a default action, Amazon EKS provisions AWS CloudFormation templates to spin up worker nodes in the Amazon EKS cluster. This AMI has been built over Amazon Linux 2 and has been configured to work as a base image for all Amazon EKS worker nodes.

The AMI has also been configured to work with Amazon EKS out-of-the-box, which includes Docker, ‘kubelet’ and AWS IAM authenticator as well.

AMI consists of a special bootstrap script which helps in automatically discovering and connecting to the user’s cluster control plane.

The AWS Cloud Formation worker node template helps in launching the worker nodes with the help of specialized Amazon EC2 user data. This user data is used as a trigger to initiate a specialized bootstrap script which makes sure that the worker nodes automatically discover and connect to the user’s cluster control plane.

Conclusion

In this post, we understood how EKS can be used to run Kubernetes on AWS without the need for the user to explicitly maintain Kubernetes control plane.