How to Use AWS Step Functions with ECS Tasks

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Are you trying to run an ECS task on AWS and wondering how to specify subnets and security groups? Here’s a straightforward way to do it using the RunTask API parameters in JSON format.

First, it’s important to know that if your subnet is a private subnet and you have a route to the NAT Gateway set up, you can still run tasks without assigning a public IP. The key is to correctly specify your network configuration.

Here’s an example of what your network configuration should look like:

json
{
“LaunchType”: “FARGATE”,
“Cluster”: “arn:aws:ecs:region:account-id:cluster/your-cluster-name”,
“TaskDefinition”: “arn:aws:ecs:region:account-id:task-definition/your-task-definition:revision”,
“NetworkConfiguration”: {
“AwsvpcConfiguration”: {
“Subnets”: [
“”
],
“SecurityGroups”: [
“”
],
“AssignPublicIp”: “ENABLED”
}
}
}

A few points to note:

If you want your task to have a public IP, keep "AssignPublicIp": "ENABLED" as shown.
Remove "AssignPublicIp" if your subnet is private and you don’t need the task to have a public IP. In this case, your task will use the private subnet’s routing, which relies on the NAT Gateway to access the internet.
Make sure your subnet IDs and security group IDs are correctly replaced.

This setup allows your ECS task to run smoothly, whether it’s on a private or public subnet, by properly configuring network settings. Just update the JSON with your specific details, and you’re all set to run your ECS tasks effectively.