Amazon ECS on AWS Fargate - Amazon Elastic Container Service
Task definitionsTasks and servicesPrivate registry authenticationClustersFargate SpotUsage metricsTask retirementSavings Plans

Amazon ECS on AWS Fargate

AWS Fargate is a technology that you can use with Amazon ECS to run containers without having to manage servers or clusters of Amazon EC2 instances. With AWS Fargate, you no longer have to provision, configure, or scale clusters of virtual machines to run containers. This removes the need to choose server types, decide when to scale your clusters, or optimize cluster packing.

When you run your tasks and services with the Fargate launch type, you package your application in containers, specify the CPU and memory requirements, define networking and IAM policies, and launch the application. Each Fargate task has its own isolation boundary and does not share the underlying kernel, CPU resources, memory resources, or elastic network interface with another task.

This topic describes the different components of Fargate tasks and services, and calls out special considerations for using Fargate with Amazon ECS.

Amazon ECS on AWS Fargate is supported in the following Regions. The supported Availability Zone IDs are noted when applicable.

Region Name Region

US East (Ohio)

us-east-2

US East (N. Virginia)

us-east-1

US West (N. California)

us-west-1 (usw1-az1 & usw1-az3 only)

US West (Oregon)

us-west-2

Africa (Cape Town)

af-south-1

Asia Pacific (Hong Kong)

ap-east-1

Asia Pacific (Mumbai)

ap-south-1

Asia Pacific (Osaka)

ap-northeast-3

Asia Pacific (Seoul)

ap-northeast-2

Asia Pacific (Singapore)

ap-southeast-1

Asia Pacific (Sydney)

ap-southeast-2

Asia Pacific (Tokyo)

ap-northeast-1 (apne1-az1, apne1-az2, & apne1-az4 only)

Canada (Central)

ca-central-1 (cac1-az1 & cac1-az2 only)

China (Beijing)

cn-north-1 (cnn1-az1 & cnn1-az2 only)

China (Ningxia)

cn-northwest-1

Europe (Frankfurt)

eu-central-1

Europe (Ireland)

eu-west-1

Europe (London)

eu-west-2

Europe (Paris)

eu-west-3

Europe (Milan)

eu-south-1

Europe (Stockholm)

eu-north-1

South America (São Paulo)

sa-east-1

Middle East (Bahrain)

me-south-1

AWS GovCloud (US-East)

us-gov-east-1

AWS GovCloud (US-West)

us-gov-west-1

The following walkthroughs help you get started using AWS Fargate with Amazon ECS:

Task definitions

Amazon ECS tasks on Fargate do not support all of the task definition parameters that are available. Some parameters are not supported at all, and others behave differently for Fargate tasks.

The following task definition parameters are not valid in Fargate tasks:

  • disableNetworking

  • dnsSearchDomains

  • dnsServers

  • dockerSecurityOptions

  • extraHosts

  • gpu

  • ipcMode

  • links

  • pidMode

  • placementConstraints

  • privileged

  • systemControls

The following task definition parameters are valid in Fargate tasks, but have limitations that should be noted:

  • linuxParameters – When specifying Linux-specific options that are applied to the container, for capabilities the add parameter is not supported. The devices, sharedMemorySize, and tmpfs parameters are not supported. For more information, see Linux Parameters.

  • volumes – Fargate tasks only support bind mount host volumes, so the dockerVolumeConfiguration parameter is not supported. For more information, see Volumes.

To ensure that your task definition validates for use with Fargate, you can specify the following when you register the task definition:

  • In the AWS Management Console, for the Requires Compatibilities field, specify FARGATE.

  • In the AWS CLI, specify the --requires-compatibilities option.

  • In the Amazon ECS API, specify the requiresCompatibilities flag.

Network mode

Amazon ECS task definitions for Fargate require that the network mode is set to awsvpc. The awsvpc network mode provides each task with its own elastic network interface. For more information, see Amazon ECS task networking.

A network configuration is also required when creating a service or manually running tasks. For more information, see Task networking.

Task CPU and memory

Amazon ECS task definitions for Fargate require that you specify CPU and memory at the task level. Although you can also specify CPU and memory at the container level for Fargate tasks, this is optional. Most use cases are satisfied by only specifying these resources at the task level. The table below shows the valid combinations of task-level CPU and memory.

CPU value

Memory value

256 (.25 vCPU)

0.5 GB, 1 GB, 2 GB

512 (.5 vCPU)

1 GB, 2 GB, 3 GB, 4 GB

1024 (1 vCPU)

2 GB, 3 GB, 4 GB, 5 GB, 6 GB, 7 GB, 8 GB

2048 (2 vCPU)

Between 4 GB and 16 GB in 1-GB increments

4096 (4 vCPU)

Between 8 GB and 30 GB in 1-GB increments

Task resource limits

Amazon ECS task definitions for Fargate support the ulimits parameter to define the resource limits to set for a container.

Amazon ECS tasks hosted on Fargate use the default resource limit values set by the operating system with the exception of the nofile resource limit parameter which Fargate overrides. The nofile resource limit sets a restriction on the number of open files that a container can use. The default nofile soft limit is 1024 and hard limit is 4096.

The following is an example task definition snippet that shows how to define a custom nofile limit that has been doubled: 

"ulimits": [
    {
       "name": "nofile",
       "softLimit": 2048,
       "hardLimit": 8192
    }
]

For more information on the other resource limits that can be adjusted, see Resource limits.

Logging

Amazon ECS task definitions for Fargate support the awslogs, splunk, firelens, and fluentd log drivers for the log configuration.

The awslogs log driver configures your Fargate tasks to send log information to Amazon CloudWatch Logs. The following shows a snippet of a task definition where the awslogs log driver is configured: 

"logConfiguration": { 
   "logDriver": "awslogs",
   "options": { 
      "awslogs-group" : "/ecs/fargate-task-definition",
      "awslogs-region": "us-east-1",
      "awslogs-stream-prefix": "ecs"
}

For more information about using the awslogs log driver in a task definition to send your container logs to CloudWatch Logs, see Using the awslogs log driver.

For more information about the firelens log driver in a task definition, see Custom log routing.

For more information about using the splunk log driver in a task definition, see Example: splunk log driver.

Amazon ECS task execution IAM role

There is an optional task execution IAM role that you can specify with Fargate to allow your Fargate tasks to make API calls to Amazon ECR. The API calls pull container images as well as calling CloudWatch to store container application logs. For more information, see Amazon ECS task execution IAM role.

Example task definition

The following is an example task definition that sets up a web server using the Fargate launch type: 

{
   "containerDefinitions": [ 
      { 
         "command": [
            "/bin/sh -c \"echo '<html> <head> <title>Amazon ECS Sample App</title> <style>body {margin-top: 40px; background-color: #333;} </style> </head><body> <div style=color:white;text-align:center> <h1>Amazon ECS Sample App</h1> <h2>Congratulations!</h2> <p>Your application is now running on a container in Amazon ECS.</p> </div></body></html>' >  /usr/local/apache2/htdocs/index.html && httpd-foreground\""
         ],
         "entryPoint": [
            "sh",
            "-c"
         ],
         "essential": true,
         "image": "httpd:2.4",
         "logConfiguration": { 
            "logDriver": "awslogs",
            "options": { 
               "awslogs-group" : "/ecs/fargate-task-definition",
               "awslogs-region": "us-east-1",
               "awslogs-stream-prefix": "ecs"
            }
         },
         "name": "sample-fargate-app",
         "portMappings": [ 
            { 
               "containerPort": 80,
               "hostPort": 80,
               "protocol": "tcp"
            }
         ]
      }
   ],
   "cpu": "256",
   "executionRoleArn": "arn:aws:iam::012345678910:role/ecsTaskExecutionRole",
   "family": "fargate-task-definition",
   "memory": "512",
   "networkMode": "awsvpc",
   "requiresCompatibilities": [ 
       "FARGATE" 
    ]
}

Task storage

For Fargate tasks, the following storage types are supported:

  • Amazon EFS volumes for persistent storage. For more information, see Amazon EFS volumes.

  • Ephemeral storage for nonpersistent storage.

When provisioned, each Amazon ECS task on Fargate receives the following ephemeral storage.

Fargate tasks using platform version 1.4.0 or later

For Amazon ECS on Fargate tasks using platform version 1.4.0 or later, each task receives 20 GB of ephemeral storage. The amount of storage is not adjustable.

For tasks using platform version 1.4.0 or later that are launched on May 28, 2020 or later, the ephemeral storage is encrypted with an AES-256 encryption algorithm using an AWS Fargate-managed encryption key.

Fargate tasks using platform version 1.3.0 or earlier

For Amazon ECS on Fargate tasks using platform version 1.3.0 or earlier, each task receives the following ephemeral storage.

  • 10 GB of Docker layer storage

  • An additional 4 GB for volume mounts. This can be mounted and shared among containers using the volumes, mountPoints and volumesFrom parameters in the task definition.

    Note

    The host and sourcePath parameters are not supported for Fargate tasks.

Tasks and services

After you have your Amazon ECS task definitions for Fargate prepared, there are some decisions to make when creating your service.

Task networking

Amazon ECS tasks for Fargate require the awsvpc network mode, which provides each task with an elastic network interface. When you run a task or create a service with this network mode, you must specify one or more subnets to attach the network interface and one or more security groups to apply to the network interface.

If you are using public subnets, decide whether to provide a public IP address for the network interface. For a Fargate task in a public subnet to pull container images, a public IP address needs to be assigned to the task's elastic network interface, with a route to the internet or a NAT gateway that can route requests to the internet. For a Fargate task in a private subnet to pull container images, the private subnet requires a NAT gateway be attached to route requests to the internet. For more information, see Amazon ECS task networking.

The following is an example of the networkConfiguration section for a Fargate service: 

"networkConfiguration": { 
   "awsvpcConfiguration": { 
      "assignPublicIp": "ENABLED",
      "securityGroups": [ "sg-12345678" ],
      "subnets": [ "subnet-12345678" ]
   }
}

Service load balancing

Your Amazon ECS service on Fargate can optionally be configured to use Elastic Load Balancing to distribute traffic evenly across the tasks in your service.

Amazon ECS services on Fargate support the Application Load Balancer and Network Load Balancer load balancer types. Application Load Balancers are used to route HTTP/HTTPS (or layer 7) traffic. Network Load Balancers are used to route TCP or UDP (or layer 4) traffic. For more information, see Load balancer types.

When you create a target group for these services, you must choose ip as the target type, not instance. This is because tasks that use the awsvpc network mode are associated with an elastic network interface, not an Amazon EC2 instance. For more information, see Service load balancing.

Using a Network Load Balancer to route UDP traffic to your Amazon ECS on Fargate tasks is only supported when using platform version 1.4 and for tasks launched in the following Regions:

  • US East (N. Virginia) - us-east-1

  • US West (Oregon) - us-west-2

  • EU (Ireland) - eu-west-1

  • Asia Pacific (Tokyo) - ap-northeast-1

Private registry authentication

Amazon ECS tasks for Fargate can authenticate with private image registries, including Docker Hub, using basic authentication. When you enable private registry authentication, you can use private Docker images in your task definitions.

To use private registry authentication, you create a secret with AWS Secrets Manager containing the credentials for your private registry. Then, within your container definition, you specify repositoryCredentials with the full ARN of the secret that you created. The following snippet of a task definition shows the required parameters: 

"containerDefinitions": [
   {
      "image": "private-repo/private-image",
      "repositoryCredentials": {
         "credentialsParameter: "arn:aws:secretsmanager:region:aws_account_id:secret:secret_name"
      }
   }
]

For more information, see Private registry authentication for tasks.

Clusters

Clusters may contain tasks using both the Fargate and EC2 launch types. When viewing your clusters in the AWS Management Console, Fargate and EC2 task counts are displayed separately.

For more information about Amazon ECS clusters, including a walkthrough for creating a cluster, see Amazon ECS clusters.

Fargate Spot

Amazon ECS capacity providers enable you to use both Fargate and Fargate Spot capacity with your Amazon ECS tasks.

With Fargate Spot you can run interruption tolerant Amazon ECS tasks at a discounted rate compared to the Fargate price. Fargate Spot runs tasks on spare compute capacity. When AWS needs the capacity back, your tasks will be interrupted with a two-minute warning. For more information, see AWS Fargate capacity providers.

Usage metrics

You can use CloudWatch usage metrics to provide visibility into your accounts usage of resources. Use these metrics to visualize your current service usage on CloudWatch graphs and dashboards.

AWS Fargate usage metrics correspond to AWS service quotas. You can configure alarms that alert you when your usage approaches a service quota. For more information about Fargate service quotas, see AWS Fargate service quotas.

For more information about AWS Fargate usage metrics, see Fargate usage metrics in the Amazon Elastic Container Service User Guide for AWS Fargate.

Task retirement

A Fargate task is scheduled to be retired when AWS detects the irreparable failure of the underlying hardware hosting the task or if a security issue needs to be patched. Most security patches are handled transparently without requiring any action on your part or having to restart your tasks. But for certain issues, we may require that the task be restarted.

When a task reaches its scheduled retirement date, it is stopped or terminated by AWS. If the task is part of a service, then the task is automatically stopped and the service scheduler starts a new one to replace it. If you are using standalone tasks, then you receive notification of the task retirement. For more information, see Task retirement.

Savings Plans

Savings Plans are a pricing model that offer significant savings on AWS usage. You commit to a consistent amount of usage, in USD per hour, for a term of 1 or 3 years, and receive a lower price for that usage. For more information, see the Savings Plans User Guide.

To create a Savings Plan for your Fargate usage, use the Compute Savings Plans type. To get started, see Getting started with Savings Plans in the Savings Plans User Guide.