Is AWS ECS with Terraform broken?

Question

I am trying to spin up an ECS cluster with Terraform, but can not make EC2 instances register as container instances in the cluster.

I first tried with the verified module from Terraform, but this seems out dated (ecs-instance-profile has wrong path).

Then I tried with another module from anrim, but still no container instances. Here is the script I used:

provider "aws" {
  region = "us-east-1"
}

module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "2.21.0"

  name               = "ecs-alb-single-svc"
  cidr               = "10.10.10.0/24"
  azs                = ["us-east-1a", "us-east-1b", "us-east-1c"]
  private_subnets    = ["10.10.10.0/27", "10.10.10.32/27", "10.10.10.64/27"]
  public_subnets     = ["10.10.10.96/27", "10.10.10.128/27", "10.10.10.160/27"]

  tags = {
    Owner       = "user"
    Environment = "me"
  }
}

module "ecs_cluster" {
  source = "../../modules/cluster"

  name        = "ecs-alb-single-svc"
  vpc_id      = module.vpc.vpc_id
  vpc_subnets = module.vpc.private_subnets

  tags = {
    Owner       = "user"
    Environment = "me"
  }
}

I then created a new ecs cluster (from the aws console) on the same VPC and carefully compared the differences in resources. I managed to find some small differences, fixed them and tried again. But still no container instances!

A fork of the module is available here.

It works fine and plenty of people, myself included, use Terraform to create ECS clusters and services. Are you saying you get instances spun up but they aren't joined to an ECS cluster? What do the relevant cloud-init logs have to say? — ydaetskcoR

Marcin Wyszynski Marcin Wyszynski · Accepted Answer · 2019-12-19T20:34:45

Can you see instances being created in the autoscaling group? If so, I'd suggest SSHing to one of them (either directly or using a bastion host, eg. see this module) and checking ECS agent logs. In my experience those problems are usually related to IAM policies, and that's pretty visible in logs but YMMV.

Is AWS ECS with Terraform broken?

1 Answers