ECS

Abstract

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• A lightweight container orchestration service
• We can mount Volume to it for data that can’t be lost when Container is terminated

Components

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Container

• We can obtain a shell into it using ECS Exec
• Obtain Private IP of the container, must have curl && jq

containerPrivateIP=$(curl $ECS_CONTAINER_METADATA_URI | jq -r '.Networks[0].IPv4Addresses[0]') >/dev/null 2>&1

Task

• A logical grouping of one or more Container

Task Definition

• Similar to EC2 Launch Template
• Required to spin up Task
• It defines the Hardware Details, IAM Role, Docker Image and Docker Container Config (AMI Config like User Data Script)

Hardware Details

• "cpu": 256 means 256/1024 vCPU
• Click here to find out more about the hardware configuration

Service

• Similar to Auto Scaling Group in EC2

Defines

• What Task Definition to use
• VPC (like which VPC Subnet to use)
• Connecting to AWS ALB & Target Group
• Auto Scaling Group

Terminologies

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Volume

• 2 types - Bind Mounts & EFS Volumes
• ECS Fargate can only use EFS Volumes, Bind Mounts are local file system volumes mounted directly from the host to the container. But ECS Fargate is Serverless

Fargate

• The serverless version of ECS
• The one and only one Deployment Strategy is Spread
• Doesn’t have control over Deployment Strategy like the ECS powered by EC2. Because Fargate is serverless, so we don’t really have to consider which az’s ec2 instance has more cpu power, thus deploy new task to that ec2 in that az