Containers provide a standard way to virtually package your code, configs, and dependencies in a single object. Docker containers greatly simplify implementation and Kubernetes meets the need for orchestrating multiple containers due to scalability requirements.
AWS offers two services that serve the need of container orchestration. We will look into the pros and cons of these services for microservices and cloud architecture in this article: Amazon Elastic Container Service (Amazon ECS) and Amazon Elastic Kubernetes Service (Amazon EKS). There are definite differences between these services in terms of design and operations, but both support several compute options and have rich integration points to work with other AWS services. We intentionally focus on the similarities and differences between ECS and EKS services of AWS in this article to help you decide which of these services is right for you. Let's examine the reasons why AWS created both services and which one is suitable for specific cases.
Amazon Elastic Container Service
Amazon ECS is a highly scalable container orchestration service designed to manage Docker containers. ECS natively integrates with other AWS services, such as AWS IAM, Amazon, VPC, Amazon Secrets Manager, and Amazon CloudWatch, to offer a comprehensive experience to AWS customers. ECS is highly scalable, reliable, and secure. You can launch containers on the desired compute options that are provided, such as AWS Fargate or EC2 instances. The following diagram summarizes how ECS works:
Figure 1: How ECS works (by AWS ECS Documentation)
ECS is widely used to run microservice applications on Docker containers for machine-learning and batch-processing use cases. You can create secure and reliable microservice applications and run them on AWS with its easy-to-use API.
Amazon Elastic Kubernetes Service
Amazon EKS is the managed Kubernetes service of AWS that makes it easy to set up Kubernetes on AWS. It runs upstream and certifies Kubernetes on AWS infrastructure, which enables you to migrate any Kubernetes application to EKS without needing to make code changes. To save on cost, you can connect EC2 spot instances or Fargate automatic provision on-demand serverless compute for your applications by using managed node groups of EKS. The following diagram shows how EKS works:
Figure 2: How EKS works (by AWS EKS Documentation)
In 2021, EKS is split into three services for different environments:
- Amazon EKS provides fully managed clusters to run your applications on AWS infrastructure. You can standardize operations across many environments.
- Amazon EKS Distro is an open source Kubernetes distribution used to help create clusters. It is deployable both on premises and on the cloud.
- Amazon EKS Anywhere enables you to host, create, and operate Kubernetes clusters on-premises.
EKS allows you to deploy applications using Terraform, Kubernetes Dashboard, kubectl, Helm, and more. All EKS-managed applications are compatible with applications managed by any Kubernetes environment. This means you can integrate a Kubernetes-managed application on a different cloud environment with your AWS EKS-managed application.
Let’s compare and contrast both services by looking at some important key factors.
Similarities and Differences
ECS and EKS are both AWS-managed services with a specific focus on containers and microservice applications. Although they have some architectural and operational resemblance, there are few essential differences between them. Below you will see some important topics to consider listed with explanations of how both services compare in terms of these considerations.
Compatibility and Portability
Amazon EKS is a managed Kubernetes service that you can run on any infrastructure, from on-premises to all cloud vendors. EKS is designed to work anywhere by design, but it’s not the same for ECS; ECS is designed and served solely for workloads running on the AWS cloud. Vendor lock-in is a fear that diminishes day by day, but for those who are still worried about this issue, EKS is the ultimate choice.
When it comes to portability (i.e., moving between cloud vendors with minimal disruption), EKS is based on an open source Kubernetes that makes portability viable; in contrast, ECS is an exclusive AWS service that is not available for other infrastructures.
If you do not have a concern about vendor lock-in and want to build AWS-native applications, then ECS is a good choice for taking advantage of managed and easy containerization. However, if you design your applications to run on Kubernetes while also including other cloud providers, on-premise setups, or your laptop, then Kubernetes in EKS will help you package your containers and move to another platform quickly.
Amazon Web Services provide a standard level of security, availability, and reliability for all of their services. ECS and EKS both have access to AWS Identity and Access Management (IAM), the access control system through which you can limit access to ECS tasks or EKS pods. The difference between these services is strictly operational. While ECS has a deep integration with IAM, EKS needs some add-ons to enable this functionality. There are options (e.g., KIAM) that allow similar functions in an EKS environment, but these options will result in extra cost for this additional system complexity.
All cloud vendors charge for traffic on their services, but they offer ways to optimize costs. For both ECS and EKS services, AWS charges for resources used by your applications. This means that if you allocate EC2 instances or use Fargate as a compute resource, you will be charged according to those services costs because you run your ECS tasks or Kubernetes pods on them. However, if you use EKS, you will be charged $0.10 per hour for each EKS cluster you have. This cost may seem minimal, but it can quickly empty your pockets if you create multiple clusters for each developer or team.
Due to the extra cost for EKS, if you are just getting started or exploring microservices, then ECS might make more sense for you to use cost-wise. But on the other hand, if you are already ready-to-go and also need Kubernetes scalability, then EKS’s additional cost may be negligible for your situation.
Your choice between these services may vary depending on your expertise and knowledge. ECS is a simple service for developers to manage, but EKS is a complete control plane. Additionally, ECS has a simple API where you can create containerized applications without having to deal with complex abstractions while in EKS, you need to use the Kubernetes control plane to form Kubernetes clusters on AWS to then create your containerized applications. To sum up: Much more expertise is required to use EKS rather than ECS.
Support is one of the most important aspects to consider when comparing two services. Since EKS has open source roots for a managed Kubernetes service, it highly benefits from community support. In contrast, AWS is the only guarantor for solving issues with ECS. In this regard, the open source Kubernetes EKS has indisputable advantages over ECS due to the fact that you can benefit from community-based support, such as Github posts, Slack channels, or Stack Overflow, while also having access to free and rich resources such as blogs, tutorials, and online courses like official Kubernetes training. And lastly, you do have the ability to use community-maintained applications and tools, such as Helm Charts, Kubernetes Operators, or kubectl extensions.
Choosing between ECS and EKS will depend on your project requirements. What both services have in common is that they support running applications on one or more compute resources in order to provide flexibility on cost, performance, high availability, and reliability.
If you develop serverless applications, then AWS Fargate might be the option for you. If you are solely maintaining your applications on your premises, then AWS Outposts can be a life vest. If high availability and high performance is required for your users around the world, then AWS Local Zones could be preferred to serve this need. And if you do not know which option to choose and your applications run on VMs, you can opt for a different option available from the wide range of EC2 instances.
The computing platforms mentioned above have substantial differences in management complexity and financial commitment, meaning what works well for one developer may not work well for another.
AWS provides secure, reliable, and scalable container management systems, including ECS and EKS. Whether a single developer or large software team is trying to decide what meets their needs, their ultimate choice should be based on not just project requirements, but also on their cloud vision, expertise, and customers’ requirements.
In summary, both ECS and EKS are good options depending on your situation. If you don’t want to rely on only one cloud vendor and you’re considering developing multi-cloud or hybrid cloud architectures, then EKS is your best choice. If you are developing and operating large-scale projects where many teams will collaborate on several deployments and products simultaneously, then EKS is the best option. Lastly, EKS is a better option if you and your team already have Kubernetes-native applications and expertise.
On the other hand, ECS is a great option if you are looking for a free control plane and easy-to-use API. Additionally, you should choose ECS if you are new to containerization and microservices, if you’re testing the waters, or if you have a small team and want to be agile with fewer things to manage. Lastly, ECS is your best choice if you need an AWS-native solution to integrate easily with other AWS solutions.