ECS

• used to run Docker containers and has 3 flavors:
  • ECS "Classic": provision EC2 instances to run containers
  • Fargate: ECS serverless, no need to provision EC2
  • EKS: managed Kubernetes by AWS

ECS Clusters

• logical grouping of EC2 instances
• EC2 instances run the ECS agent (Docker container)
• The ECS agents registers the instance to the ECS cluster
• The ECS instances run a special AMI, made specifically for ECS
• EC2 instances must enable config ECS_ENABLE_TASK_IAM_ROLE in /etc/ecs/ecs.config file (automatically setup by ECS)

ECS Task Definitions

• Tasks definitions are metadata in JSON form to tell ECS how to run a Docker Container
• Information about:
  • Image Name
  • Port Binding for Container and Host
  • Memory and CPU required
  • Environment variables
  • Networking information

EC2 Service

• ECS Services help define how many tasks should run and how they should be run
• ensure that the number of tasks desired is running across our fleet of EC2 instances
• can be linked to ELB / NLB / ALB

ECS Service with Load Balancer

• must not specify a host port (only container port)
• use ALB with dynamic port mapping