AWS ECS & Fargate — Container Services

AWS ECS & Fargate — Container Services

Amazon Elastic Container Service (ECS) is a fully managed container orchestration service. Fargate is a serverless compute engine for containers that removes the need to manage EC2 servers.

In Azure terms: ECS ≈ Azure Container Apps (Fargate) / Azure Container Instances (ACI) / VMSS-backed container hosting

ECS Core Concepts

Concept	Description
Cluster	Logical grouping of compute resources for running tasks and services
Task Definition	Blueprint for your container(s) — image, CPU, memory, ports, env vars, IAM role
Task	A running instance of a Task Definition (one-off execution)
Service	Maintains a desired count of running tasks, integrates with load balancers
Container	The individual Docker container within a task
ECR	Elastic Container Registry — private Docker image registry

ECS Launch Types

Launch Type	Description	Azure Equivalent
Fargate	Serverless — AWS manages the underlying EC2 servers	Azure Container Apps / ACI
EC2	You manage a fleet of EC2 instances for ECS to place containers on	Azure Container Instances on VMSS
External (ECS Anywhere)	Run ECS on your own on-prem or edge servers	Azure Arc

Fargate — Serverless Containers

With Fargate you only specify CPU and memory — no server management:

You define:          AWS manages:
- Task Definition    - EC2 hosts
- CPU/Memory         - Patching
- Container image    - Scaling compute
- VPC/Security Group

Supported CPU/Memory combinations:

vCPU	Memory Options
0.25 vCPU	0.5, 1, 2 GB
0.5 vCPU	1, 2, 3, 4 GB
1 vCPU	2–8 GB
2 vCPU	4–16 GB
4 vCPU	8–30 GB
8 vCPU	16–60 GB
16 vCPU	32–120 GB

Sample Task Definition (JSON)

{
  "family": "my-web-app",
  "networkMode": "awsvpc",
  "requiresCompatibilities": ["FARGATE"],
  "cpu": "512",
  "memory": "1024",
  "executionRoleArn": "arn:aws:iam::123456789:role/ecsTaskExecutionRole",
  "containerDefinitions": [
    {
      "name": "web",
      "image": "123456789.dkr.ecr.us-east-1.amazonaws.com/my-app:latest",
      "portMappings": [{ "containerPort": 8080, "protocol": "tcp" }],
      "environment": [
        { "name": "ENV", "value": "production" }
      ],
      "logConfiguration": {
        "logDriver": "awslogs",
        "options": {
          "awslogs-group": "/ecs/my-web-app",
          "awslogs-region": "us-east-1",
          "awslogs-stream-prefix": "ecs"
        }
      }
    }
  ]
}

ECR — Elastic Container Registry

ECR is AWS’s private Docker container registry — equivalent to Azure Container Registry (ACR):

# Authenticate Docker to ECR
aws ecr get-login-password --region us-east-1 | \
  docker login --username AWS --password-stdin 123456789.dkr.ecr.us-east-1.amazonaws.com

# Create a repository
aws ecr create-repository --repository-name my-app

# Build and push
docker build -t my-app .
docker tag my-app:latest 123456789.dkr.ecr.us-east-1.amazonaws.com/my-app:latest
docker push 123456789.dkr.ecr.us-east-1.amazonaws.com/my-app:latest

ECS Service + ALB Pattern

A standard production deployment:

Internet → ALB (Application Load Balancer)
              ↓
         Target Group
              ↓
    ECS Fargate Service (desired count: 3)
    ├── Task 1 (container: my-app)
    ├── Task 2 (container: my-app)
    └── Task 3 (container: my-app)

ECS handles:

• Health checks and task replacement
• Rolling deployments (or blue/green via CodeDeploy)
• Auto-scaling based on CPU/memory/custom metrics

ECS vs EKS — When to Choose

Factor	ECS	EKS (Kubernetes)
Simplicity	Simpler AWS-native API	More complex but industry-standard
AWS integration	Deep (IAM, ALB, CloudWatch)	Good (but requires more config)
Portability	AWS-only	Kubernetes — portable across clouds
Learning curve	Lower	Higher
Community ecosystem	AWS-specific	Massive Kubernetes ecosystem

Rule of thumb: Use ECS (Fargate) if you want simplicity and stay AWS-native. Use EKS if you need Kubernetes compatibility, advanced scheduling, or portability.

CLI Examples

# Register a task definition
aws ecs register-task-definition --cli-input-json file://task-def.json

# Create a cluster
aws ecs create-cluster --cluster-name my-cluster

# Run a one-off task
aws ecs run-task \
  --cluster my-cluster \
  --task-definition my-web-app \
  --launch-type FARGATE \
  --network-configuration "awsvpcConfiguration={subnets=[subnet-abc],securityGroups=[sg-abc],assignPublicIp=ENABLED}"

# List running tasks
aws ecs list-tasks --cluster my-cluster

# Describe a service
aws ecs describe-services \
  --cluster my-cluster \
  --services my-service

Useful Links

• ECS Documentation
• Fargate Pricing
• ECR Documentation