The module container-defitinion does not work when using aws_ecs_task_definition as target

[lays147]

Description

(Is it a bug or a feature?)

I'm trying to use the container-definition module to set up a standalone ecs task that I'll trigger manually. However, the module outputs the json of the container definition without setting into an array that is expected as the input of container_definitions of aws_ecs_task_definition.

If the module is intended to be used only together with the service module, this should be highlighted in the docs.

Versions

• Module version [Required]:
  6.0.6

Terraform v1.12.2
on linux_amd64

• provider registry.terraform.io/hashicorp/aws v6.4.0

Reproduction Code [Required]

module "ecs_container_definition" {
  source = "terraform-aws-modules/ecs/aws//modules/container-definition"
  version = "~> 6.0"

  name      = "test"
  cpu       = 512
  memory    = 256
  essential = true
  image     = "hello-world:latest"
}

resource "aws_ecs_task_definition" "this" {
  family                   = "test"
  container_definitions    = module.ecs_container_definition.container_definition_json
  requires_compatibilities = ["FARGATE"]
  network_mode             = "awsvpc"
  task_role_arn            = aws_iam_role.task_access.arn
  execution_role_arn       = aws_iam_role.task_execution.arn
  cpu       = 512
  memory    = 256
}

Steps to reproduce the behavior:

Try to run the terraform code above and you get an error.

Expected behavior

It should work with aws_ecs_task_definition.

Actual behavior

Planning failed. Terraform encountered an error while generating this plan.

╷
│ Error: ECS Task Definition container_definitions is invalid: json: cannot unmarshal object into Go value of type []types.ContainerDefinition
│ 
│   with aws_ecs_task_definition.this,
│   on ecs-task.tf line 16, in resource "aws_ecs_task_definition" "this":
│   16:   container_definitions    = module.ecs_container_definition.container_definition_json
│ 

Output from module.ecs_container_definition.container_definition_json

"{\"cpu\":256,\"entrypoint\":[],\"environment\":[],\"environmentFiles\":[],\"essential\":true,\"image\":\"hello-world:latest\",\"interactive\":false,\"linuxParameters\":{\"initProcessEnabled\":false},\"logConfiguration\":{\"logDriver\":\"awslogs\",\"options\":{\"awslogs-group\":\"/aws/ecs/iam-auth-rds\",\"awslogs-region\":\"us-east-1\",\"awslogs-stream-prefix\":\"ecs\"}},\"memory\":512,\"mountPoints\":[],\"name\":\"iam-auth-rds\",\"privileged\":false,\"pseudoTerminal\":false,\"readonlyRootFilesystem\":true,\"restartPolicy\":{\"enabled\":true,\"ignoredExitCodes\":[]},\"startTimeout\":30,\"stopTimeout\":120,\"systemControls\":[],\"versionConsistency\":\"disabled\",\"volumesFrom\":[]}"

Since the output is not a list of containers, it is incompatible with the input of the resource.

[bryantbiggs]

hmm, perhaps in hindsight the container_definition_json intention wasn't well formed.

Instead, you can do jsonencode([module.ecs_container_definition.container_definition])