How to Use AWS Fargate with ECS: Simple Guide

To use Fargate with ECS, create an ECS cluster and define a task using the Fargate launch type. Then run your containerized application without managing servers by specifying Fargate in your task definition and service.

Syntax

Using Fargate with ECS involves defining a task and service with the FARGATE launch type. Key parts include:

• Cluster: Logical group of tasks.
• Task Definition: Blueprint for your container including image, CPU, memory.
• Launch Type: Set to FARGATE to run without managing servers.
• Network Configuration: Required for Fargate tasks to specify subnets and security groups.

bash

aws ecs create-cluster --cluster-name my-fargate-cluster

aws ecs register-task-definition \
  --family my-task \
  --network-mode awsvpc \
  --requires-compatibilities FARGATE \
  --cpu 256 \
  --memory 512 \
  --container-definitions '[{"name":"my-container","image":"nginx","portMappings":[{"containerPort":80,"protocol":"tcp"}]}]'

aws ecs create-service \
  --cluster my-fargate-cluster \
  --service-name my-service \
  --task-definition my-task \
  --desired-count 1 \
  --launch-type FARGATE \
  --network-configuration 'awsvpcConfiguration={subnets=[subnet-12345],securityGroups=[sg-12345],assignPublicIp=ENABLED}'

Example

This example creates an ECS cluster, registers a Fargate task running an NGINX container, and starts a service with one task. It shows how to specify CPU, memory, and network settings for Fargate.

bash

aws ecs create-cluster --cluster-name example-fargate-cluster

aws ecs register-task-definition \
  --family example-nginx-task \
  --network-mode awsvpc \
  --requires-compatibilities FARGATE \
  --cpu 256 \
  --memory 512 \
  --container-definitions '[{"name":"nginx-container","image":"nginx:latest","portMappings":[{"containerPort":80,"protocol":"tcp"}]}]'

aws ecs create-service \
  --cluster example-fargate-cluster \
  --service-name example-nginx-service \
  --task-definition example-nginx-task \
  --desired-count 1 \
  --launch-type FARGATE \
  --network-configuration 'awsvpcConfiguration={subnets=[subnet-abcde123],securityGroups=[sg-abcde123],assignPublicIp=ENABLED}'

Output

Created cluster: example-fargate-cluster
{"taskDefinition": {"taskDefinitionArn": "arn:aws:ecs:region:account-id:task-definition/example-nginx-task:1"}}
Created service: example-nginx-service

Common Pitfalls

Common mistakes when using Fargate with ECS include:

• Not specifying awsvpc network mode, which is required for Fargate.
• Forgetting to set requiresCompatibilities to FARGATE in the task definition.
• Omitting network configuration like subnets and security groups when creating the service.
• Assigning insufficient CPU or memory resources causing task failures.

Always double-check these settings to avoid deployment errors.

json

Wrong task definition snippet:
{
  "networkMode": "bridge",
  "requiresCompatibilities": ["EC2"]
}

Right task definition snippet:
{
  "networkMode": "awsvpc",
  "requiresCompatibilities": ["FARGATE"]
}

Quick Reference

Remember these key points when using Fargate with ECS:

• Use awsvpc network mode for Fargate tasks.
• Set requiresCompatibilities to FARGATE in task definitions.
• Specify CPU and memory according to your workload needs.
• Provide network configuration with subnets and security groups when creating services.
• Assign public IP if your task needs internet access.

Key Takeaways

Always set launch type to FARGATE and network mode to awsvpc for ECS tasks using Fargate.

Provide proper CPU, memory, and network configuration to avoid task failures.

Create an ECS cluster before registering Fargate task definitions and services.

Specify subnets and security groups in network configuration for Fargate services.

Assign public IP if your container needs internet access.