ECS/EKS

What is ECS and EKS?

• ECS = Elastic Container Service → AWS’s own container orchestration system.

• EKS = Elastic Kubernetes Service → AWS’s managed Kubernetes service.

Docker Image

Container Registry

ECS-

• AWS’s simpler container management tool.

• You tell ECS:

  • Which container image to run.

  • How many copies (tasks) to run.

  • ECS handles the rest.

How ECS Runs Containers:

• EC2 Launch Type → You manage EC2 instances, ECS puts containers on them.

• Fargate Launch Type → AWS runs the servers for you (serverless containers)

ECS Key Terms

• Cluster → A logical group of container-running resources (EC2 or Fargate).

• Task Definition → Recipe describing:

  • Which Docker image

  • CPU & memory

  • Environment variables

• Task → A running container instance from a task definition.

• Service → Keeps the desired number of tasks running

EKS-

• AWS’s managed Kubernetes service.

• Kubernetes is more powerful & flexible than ECS, but also more complex.

• AWS runs the control plane for you, you manage the worker nodes (or use Fargate).

How EKS Runs Containers

• You still use Pods, Deployments, Services (Kubernetes terms).

• EKS is just Kubernetes — but you don’t install or manage the control plane.

EKS Key Terms

• Cluster → Set of worker nodes + AWS-managed control plane.

• Node Group → EC2 instances where your Pods run.

• Pod → Smallest deployable unit in Kubernetes (holds 1 or more containers).

• Service (K8s) → How Pods talk to each other or the outside world.

Cluster Structure

Cluster detail

ECS vs EKS

Feature	ECS	EKS
Complexity	Easier to learn, AWS-specific	More complex, industry-standard
Orchestration	AWS’s own system	Kubernetes
Portability	AWS only	Any Kubernetes platform
Flexibility	Less customizable	Very flexible & extensible
Best For	Small to medium apps, fast AWS integration	Large, complex, multi-cloud architectures