How to Import an AWS ECS Task Definition into Terraform

Import AWS ECS Task Definition with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Amazon ECS resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live AWS ECS Task Definition to managed Terraform.

terraback scan all aws --region us-east-1

terraback aws import --method bulk

The Terraform import block

Terraback emits a Terraform 1.5+ import block like the one below. Because the block lives in your configuration, the import is reviewable in a pull request and repeatable across environments.

import {
  to = aws_ecs_task_definition.web
  id = "arn:aws:ecs:us-east-1:123456789012:task-definition/web:42"
}

Example aws_ecs_task_definition configuration

Here is a realistic AWS ECS Task Definition block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "aws_ecs_task_definition" "web" {
  family                   = "web"
  requires_compatibilities = ["FARGATE"]
  network_mode             = "awsvpc"
  cpu                      = "256"
  memory                   = "512"
  execution_role_arn       = "arn:aws:iam::123456789012:role/ecsTaskExecutionRole"

  container_definitions = jsonencode([{
    name      = "web"
    image     = "nginx:latest"
    essential = true
    portMappings = [{ containerPort = 80 }]
  }])
}

Gotchas when importing a AWS ECS Task Definition

• Task definitions are immutable and versioned; every change creates a new revision, so Terraform replaces rather than updates them.
• container_definitions is a JSON document that AWS normalizes heavily (adding defaults, re-ordering keys), so expect to align it to stop a perpetual diff.
• Import by the full ARN including the :revision suffix; the family name alone is not a valid import ID.
• Referenced IAM roles, log groups, and EFS volumes are separate resources and are not imported with the task definition.

Doing it manually with terraform import

The native approach is to write the aws_ecs_task_definition block by hand, then run terraform import aws_ecs_task_definition.example <import-id> for every resource, one at a time. That works for a handful of resources, but it does not scale: you author all the HCL yourself and repeat the command for each item. Terraback generates the HCL and the import blocks for your whole account in one pass.

Import other AWS resources