I'll help you set this up. Here's a complete example of how to configure your ECS Fargate worker with an EC2 work pool: 1. First, create your work pool:

bash
prefect work-pool create "my-ec2-pool" --type process

2. Create your ECS worker configuration. Save this as `ecs-worker.yaml`:

yaml
version: 1
workPool:
  name: "my-ec2-pool"

jobs:
  - name: "ecs-fargate-worker"
    schedule: null  # runs continuously
    resource_config:
      cpu: 256      # 0.25 vCPU
      memory: 512   # MB
      ephemeral_storage: 21  # GB
      task_role_arn: "arn:aws:iam::<YOUR_AWS_ACCOUNT>:role/prefect-ecs-task-role"
      execution_role_arn: "arn:aws:iam::<YOUR_AWS_ACCOUNT>:role/prefect-ecs-execution-role"
      cluster: "your-ecs-cluster-name"
      vpc_configuration:
        subnets:
          - "subnet-xxxxx"  # Replace with your subnet IDs
        security_groups:
          - "sg-xxxxx"     # Replace with your security group IDs
      launch_type: "FARGATE"
      platform_version: "LATEST"
      assign_public_ip: true  # Set to false if using private subnets

3. Deploy the worker:

bash
prefect worker start-job ecs-worker.yaml

Important notes about this configuration: 1. You'll need to replace the following placeholders: - `<YOUR_AWS_ACCOUNT>`: Your AWS account ID - `subnet-xxxxx`: Your VPC subnet ID(s) - `sg-xxxxx`: Your security group ID(s) - `your-ecs-cluster-name`: Your ECS cluster name 2. The IAM roles (

task_role_arn

and

execution_role_arn

) need appropriate permissions: - The task role needs permissions to interact with AWS services your flows will use - The execution role needs permissions to pull container images and write logs 3. Resource configurations can be adjusted based on your needs: - `cpu`: Valid values are 256 (.25 vCPU), 512 (.5 vCPU), 1024 (1 vCPU), 2048 (2 vCPU), etc. - `memory`: Must be appropriate for the CPU value selected - `ephemeral_storage`: Between 21 and 200 GB 4. The

vpc_configuration

is required for Fargate tasks. Ensure your VPC has either: - Public subnets with

assign_public_ip: true

for internet access - Private subnets with a NAT Gateway and

assign_public_ip: false

You can find more detailed configuration options and setup instructions in the Prefect ECS Guide. Would you like me to elaborate on any part of this configuration or explain how to set up the required IAM roles?

✅ thought for 37.9 seconds

Based on the GitHub issues and documentation, I can provide the correct configuration for your ECS work pool to run tasks on EC2. Here's what you need to know: When using EC2 as the launch type, you should NOT specify the

launchType

directly. Instead, you need to configure a capacity provider strategy. Here's the correct configuration for your base job template:

json
{
    "task_run_request": {
        "capacityProviderStrategy": [
            {
                "capacityProvider": "YOUR_CAPACITY_PROVIDER_NAME",
                "weight": 1,
                "base": 0
            }
        ],
        "cluster": "your-ecs-cluster-name",
        "networkConfiguration": {
            "awsvpcConfiguration": {
                "subnets": ["subnet-xxxxx"],
                "securityGroups": ["sg-xxxxx"],
                "assignPublicIp": "ENABLED"  // or "DISABLED" for private subnets
            }
        },
        "taskDefinition": "your-task-definition-arn"
    }
}

Key points about this configuration: 1. Remove any

launchType

specification - using

launchType

will actually override and ignore the capacity provider strategy 2. The

capacityProviderStrategy

configuration is required and should include: - `capacityProvider`: The name of your EC2 capacity provider - `weight`: Relative weight for the capacity provider (typically 1) - `base`: Minimum number of tasks to run on the specified provider (typically 0) 3. You'll still need the standard networking configuration: -

subnets

-

securityGroups

-

assignPublicIp

setting To create the work pool with this configuration:

bash
prefect work-pool create "my-ec2-pool" \
    --type ecs \
    --base-job-template path/to/your/template.json

Prerequisites for this to work: 1. An ECS cluster must be set up with EC2 capacity providers 2. An Auto Scaling Group (ASG) must be configured and associated with your capacity provider 3. The appropriate IAM roles and permissions must be in place Would you like me to provide more details about setting up the prerequisite AWS resources or explain any part of this configuration in more detail?

The distinction between using

launchType: "EC2"

versus capacity providers is important. Here's when each should be used: Use

launchType: "EC2"

when: 1. You're using a standalone ECS cluster without auto-scaling groups 2. You have a fixed set of EC2 instances and want direct placement of tasks on them 3. You're not using cluster auto-scaling features 4. You want simple, direct control over where tasks run Use capacity providers (without specifying launchType) when: 1. You're using Auto Scaling Groups (ASG) 2. You want automatic scaling of EC2 instances based on demand 3. You need mixed capacity types (like spot instances + on-demand) 4. You want ECS to manage the scaling and placement of tasks automatically In your case, since you mentioned using an EC2 work pool that presumably needs to scale, you should use the capacity provider strategy approach. The

launchType: "EC2"

setting would actually prevent the auto-scaling features from working properly because it bypasses the capacity provider configuration. This is why many users encounter the

RESOURCE:CPU

or

RESOURCE:MEMORY

errors when using

launchType: "EC2"

- the tasks try to launch immediately on existing instances without waiting for the auto-scaling group to provision new capacity. The capacity provider approach is more flexible and robust, allowing ECS to: - Scale your EC2 instances automatically - Wait for capacity to become available - Handle task placement more intelligently - Manage mixed instance types if needed Would you like me to provide an example of how to set up the capacity providers in your ECS cluster?

The key documentation about this behavior is found in the AWS ECS API documentation, specifically in the RunTask API Reference. Under the

capacityProviderStrategy

parameter, it states:

The capacity provider strategy to use for the task.

If a capacityProviderStrategy is specified, the launchType parameter must be omitted. If no capacityProviderStrategy or launchType is specified, the defaultCapacityProviderStrategy for the cluster is used.

Additionally, in the AWS ECS Developer Guide section on Capacity Providers, it explains that when using cluster auto scaling, you must specify capacityProviderStrategy and not launchType. This is a critical distinction that isn't always clearly documented in higher-level tools and frameworks. The behavior I described earlier about task placement and auto-scaling is a direct consequence of this API-level constraint - you can't use both simultaneously, and the presence of a launchType will override and ignore any capacity provider settings. Would you like me to provide more specific documentation links or explain how this impacts your ECS work pool configuration?