With the increased popularity of microservice-based architecture has come an increase in containerized workloads in the cloud—and services for managing them. These services ease the container deployment and lifecycle management process, helping organizations transition or grow in the cloud.

All leading cloud service providers offer a portfolio of services for containerized workloads, like managed container orchestration services, container registry, and container security services. In this article, we’ll compare the features of Elastic Container Service (ECS) and Elastic Kubernetes Service (EKS)—the two managed container orchestration solutions from AWS.

Containerized Workloads in AWS

When organizations want to run containers at scale to meet changing business demands, running independent containers is no longer an option. Such deployments need container orchestration solutions to help manage the underlying dynamics. These include on-demand resource allocation, resiliency, scaling, monitoring, and more—all of which are required for line-of-business applications.

Let’s look at AWS’ two container orchestration solutions: ECS and EKS.

Elastic Container Service (ECS)

Amazon ECS is AWS’ proprietary managed container orchestration service for running containerized applications at scale.

On the backend, ECS leverages an AWS serverless technology named Fargate, which removes the burden of managing the control plane and the nodes hosting the containers. This eliminates the overhead of keeping systems up to date with patches or scaling the compute capacity on demand. Instead, all of these tasks are handled seamlessly by the managed service.

On-demand autoscaling is handled by ECS, which optimizes the use of resources and ensures low-cost operations. ECS also integrates seamlessly with AWS ecosystems and products like AWS Application Load Balancer (ALB), Network Load Balancer (NLB) and Amazon Elastic Container Registry (ECR).

ECS uses Docker as the containerization platform for applications. While Fargate provides a serverless option to deploy containers, you can also use other compute options like Amazon EC2 instances, AWS Local Zones, AWS Wavelength, or AWS Outposts to run containers in ECS.

Learn here how to deploy your ECS cluster with Fargate using infrastructure as code.

Elastic Kubernetes Service (EKS)

Kubernetes, developed and then made open sourced by Google, is one of the most popular container orchestration platforms available. EKS is AWS’ managed Kubernetes service, catering to customers who prefer K8s for container orchestration. It also enables them to run containerized workloads on K8s clusters hosted in both the AWS cloud or on-premise.

EKS can run containerized workloads using either EC2 instances or AWS Fargate (with the latter offering a serverless option to run containers). It uses upstream and certified K8s-conformant versions so that it provides a consistent user experience for those who are already familiar with the solution.

Unlike traditional K8s clusters that are deployed and managed by users themselves, the control plane of the cluster and related activities—like provisioning, patching, and updates—are managed by the EKS service.

EKS supports edge deployments using solutions like AWS Outposts and AWS Wavelength, and can integrate with the AWS ecosystem for both container and network services. Customers can also use EKS Anywhere to deploy EKS on customer-managed VMware vSphere environments that are fully supported by AWS. The service will start supporting additional deployment targets, including bare metal deployments, in 2022.

Similarities of EKS and ECS

Both EKS and ECS offer managed container orchestration services in AWS with multiple compute options for container deployments. They offer similar features in terms of  interoperability, CI/CD integration, scale, ease of management, and more, as you can see in the list below:

• Interoperability: EKS and ECS have native integration with AWS services like container registry, load balancers, CloudWatch/CloudTrail for monitoring and logging, IAM, and more to ensure interoperability.
• Integration with CI/CD tools: AWS offers multiple tools for developing CI/CD pipelines for your applications, such as AWS CodeCommit, AWS CodePipeline, and AWS CodeBuild. Both ECS and EKS can integrate with these services to build and deploy your containerized workloads on AWS.
• Scalability: ECS and EKS support the autoscaling of resources based on usage. In ECS, autoscaling is done by increasing the number of tasks based on consumption demand. In EKS, the K8s control plane component Cluster Autoscaler handles the scaling requirements by adding or removing nodes. EKS also supports horizontal scaling based on resource utilization.
• Management and support: EKS and ECS are both managed services and customers can interact with them for day-to-day operations and management through the AWS CLI, the AWS Management Console, and through API calls. You can create and manage K8s clusters on EKS with the command line tool eksctl . ECS customers can use e csctl , a command line tool for ECS cluster management, which is equivalent to the kubectl tool for K8s.
• Cost: The pay-as-you-go model is available for both ECS and EKS, but with slightly different constructs. With ECS, you pay only for the compute resources that you configure and use, with no additional cost for the control plane. With EKS, you pay the compute charges for the EKS worker nodes—or AWS Fargate’s pay-as-you-go model charges, as well as a flat $0.10/hour charge for the control plane. EKS costs can be further optimized using spot instances.
• Hybrid Deployments: EKS and ECS provide hybrid deployment options for containers hosted in multiple environments. ECS Anywhere can be used to deploy ECS tasks in customer-managed infrastructure with container orchestration managed centrally from   AWS. With EKS Anywhere, the same EKS Distro that is deployed in AWS can be deployed to on-premises vSphere environments. The applications deployed in EKS Anywhere can be viewed and managed from the Amazon EKS dashboard.

When to Choose EKS vs. ECS?

Both EKS and ECS offload complex container orchestration and maintenance activities so that customers can focus on delivering value to their business. So, how do you choose? Consider the following factors when making a choice between EKS and ECS.

ECS

ECS is a great service for getting started because it allows you to get to market quickly. It's an especially good fit for MVPs, and the operational overhead is less than running EKS. It also offers a simplified approach for deploying containers for any of the following use cases:

• Minimal learning curve and effort—you can get started with containers without refactoring your applications for K8s.
• The cloud-native AWS container ecosystem meets the needs of your application without requiring add-ons.
• Small and medium-sized teams with limited resources to manage complex, large-scale container deployments.

EKS

If you have complex workloads, sprawling microservices interacting with each other, or a dependency on K8s native tools/features, EKS would be a better option. Some of the possible scenarios where EKS would be a better fit include:

• When the task-based approach in ECS is not suited for your application, and you need fine-grained control over placement of containers provided by K8s pods.
• When an organization has existing investments in K8s 
• Organization has built large-scale applications dependent on features of K8s, like namespaces, network policies, ingress configurations, etc.
• If you need to migrate existing K8s clusters to the cloud with minimal changes.

Conclusion

ECS and EKS provide many of the same features required for deploying and managing containers in AWS, but there are subtle differences that can help you choose which is best for your enterprise.

ECS is suited for organizations who are getting started with containers with low- or medium-complexity application architectures. It provides a quick jumpstart for container adoption with easy-to-use APIs. ECS is also suited for cost-conscious organizations, as the control plane is provided free of charge. It helps smaller teams manage the container ecosystem using AWS native tools with a minimal learning curve.

EKS targets enterprise use cases, catering to complex distributed microservice-based applications. When multiple teams collaborate in parallel on different microservices, EKS will  provide a cohesiveness for managing the application lifecycle. It is also best suited for hybrid and multicloud use cases, especially when the organization has expertise in K8s and might want to use the same technology in all environments.

While both services offer flexibility in your containerized workloads, the best fit depends on your organization’s target use case, maturity in containers, team size, and the importance of ease of use.