diff --git a/.circleci/config.yml b/.circleci/config.yml
index 73c8a10..4b9b427 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -2,7 +2,7 @@ version: 2
 jobs:
   validate:
     docker:
-      - image: trussworks/circleci-docker-primary:a18ba9987556eec2e48354848a3c9fb4d5b69ac8
+      - image: trussworks/circleci-docker-primary:tf12-4c1fd54273446484259597ae3da9deb2806498ed
     steps:
       - checkout
       - restore_cache:
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 8d31e32..5e17f67 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -17,8 +17,7 @@ repos:
       - id: markdownlint
 
   - repo: git://github.com/antonbabenko/pre-commit-terraform
-    rev: v1.12.0
+    rev: v1.18.0
     hooks:
       - id: terraform_docs
       - id: terraform_fmt
-      - id: terraform_validate_no_variables
diff --git a/README.md b/README.md
index 8e26667..d957475 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,3 @@
-<!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
 Creates an ECS service.
 
 Creates the following resources:
@@ -25,16 +24,16 @@ module "app_ecs_service" {
   name        = "app"
   environment = "prod"
 
-  ecs_cluster_name              = "cluster-name"
-  ecs_vpc_id                    = "${module.vpc.vpc_id}"
-  ecs_subnet_ids                = "${module.vpc.private_subnets}"
+  ecs_cluster                   = aws_ecs_cluster.mycluster
+  ecs_vpc_id                    = module.vpc.vpc_id
+  ecs_subnet_ids                = module.vpc.private_subnets
   tasks_desired_count           = 2
   tasks_minimum_healthy_percent = 50
   tasks_maximum_percent         = 200
 
   associate_alb      = true
-  alb_security_group = "${module.security_group.id}"
-  lb_target_group   = "${module.target_group.id}"
+  alb_security_group = module.security_group.id
+  lb_target_group    = module.target_group.id
 }
 ```
 
@@ -47,19 +46,20 @@ module "app_ecs_service" {
   name        = "app"
   environment = "prod"
 
-  ecs_cluster_name              = "cluster-name"
-  ecs_vpc_id                    = "${module.vpc.vpc_id}"
-  ecs_subnet_ids                = "${module.vpc.private_subnets}"
+  ecs_cluster                   = aws_ecs_cluster.mycluster
+  ecs_vpc_id                    = module.vpc.vpc_id
+  ecs_subnet_ids                = module.vpc.private_subnets
   tasks_desired_count           = 2
   tasks_minimum_healthy_percent = 50
   tasks_maximum_percent         = 200
 
   associate_nlb          = true
   nlb_subnet_cidr_blocks = ["10.0.0.0/24", "10.0.1.0/24", "10.0.2.0/24"]
-  lb_target_group   = "${module.target_group.id}"
+  lb_target_group   = module.target_group.id
 }
 ```
 
+<!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
 ## Inputs
 
 | Name | Description | Type | Default | Required |
@@ -77,10 +77,10 @@ module "app_ecs_service" {
 | container\_health\_check\_port | An additional port on which the container can receive a health check.  Zero means the container port can only receive a health check on the port set by the container_port variable. | string | `"0"` | no |
 | container\_image | The image of the container. | string | `"golang:1.12.5-alpine"` | no |
 | container\_port | The port on which the container will receive traffic. | string | `"80"` | no |
-| ecr\_repo\_arns | The ARNs of the ECR repos.  By default, allows all repositories. | list | `[ "*" ]` | no |
-| ecs\_cluster\_name | The name  of the ECS cluster. | string | n/a | yes |
+| ecr\_repo\_arns | The ARNs of the ECR repos.  By default, allows all repositories. | list(string) | `[ "*" ]` | no |
+| ecs\_cluster | ECS cluster object for this task. | object | n/a | yes |
 | ecs\_instance\_role | The name of the ECS instance role. | string | `""` | no |
-| ecs\_subnet\_ids | Subnet IDs for the ECS tasks. | list | n/a | yes |
+| ecs\_subnet\_ids | Subnet IDs for the ECS tasks. | list(string) | n/a | yes |
 | ecs\_use\_fargate | Whether to use Fargate for the task definition. | string | `"false"` | no |
 | ecs\_vpc\_id | VPC ID to be used by ECS. | string | n/a | yes |
 | environment | Environment tag, e.g prod. | string | n/a | yes |
@@ -90,7 +90,7 @@ module "app_ecs_service" {
 | logs\_cloudwatch\_group | CloudWatch log group to create and use. Default: /ecs/{name}-{environment} | string | `""` | no |
 | logs\_cloudwatch\_retention | Number of days you want to retain log events in the log group. | string | `"90"` | no |
 | name | The service name. | string | n/a | yes |
-| nlb\_subnet\_cidr\_blocks | List of Network Load Balancer (NLB) CIDR blocks to allow traffic from. | list | `[]` | no |
+| nlb\_subnet\_cidr\_blocks | List of Network Load Balancer (NLB) CIDR blocks to allow traffic from. | list(string) | `[]` | no |
 | target\_container\_name | Name of the container the Load Balancer should target. Default: {name}-{environment} | string | `""` | no |
 | tasks\_desired\_count | The number of instances of a task definition. | string | `"1"` | no |
 | tasks\_maximum\_percent | Upper limit on the number of running tasks. | string | `"200"` | no |
@@ -113,15 +113,10 @@ module "app_ecs_service" {
 
 ## Upgrade Path
 
-### 1.14.0 to 1.15.0
-
-In upgrading to this version you need to pass through the ECS Cluster Name and not the ECS Cluster ARN.
-The difference would be changing `ecs_cluster_arn` to `ecs_cluster_name` and passing in the name info.
-The module will take care of pulling the ARN from the ECS Cluster data resource on your behalf.
+### 1.15.0 to 2.0.0
 
-If you decide you do not want metric alarms you can also set two more settings:
-
-```hcl
-  cloudwatch_alarm_cpu_enable = false
-  cloudwatch_alarm_mem_enable = false
-```
+v2.0.0 of this module is built against Terraform v0.12. In addition to
+requiring this upgrade, the v1.15.0 version of the module took the name
+of the ECS cluster as a parameter; v2.0.0 takes the actual object of the
+ECS cluster as a parameter instead. You will need to update previous
+instances of this module with the altered parameter.
diff --git a/main.tf b/main.tf
index d456769..a32b689 100644
--- a/main.tf
+++ b/main.tf
@@ -25,16 +25,16 @@
  *   name        = "app"
  *   environment = "prod"
  *
- *   ecs_cluster_name              = "cluster-name"
- *   ecs_vpc_id                    = "${module.vpc.vpc_id}"
- *   ecs_subnet_ids                = "${module.vpc.private_subnets}"
+ *   ecs_cluster                   = aws_ecs_cluster.mycluster
+ *   ecs_vpc_id                    = module.vpc.vpc_id
+ *   ecs_subnet_ids                = module.vpc.private_subnets
  *   tasks_desired_count           = 2
  *   tasks_minimum_healthy_percent = 50
  *   tasks_maximum_percent         = 200
  *
  *   associate_alb      = true
- *   alb_security_group = "${module.security_group.id}"
- *   lb_target_group   = "${module.target_group.id}"
+ *   alb_security_group = module.security_group.id
+ *   lb_target_group    = module.target_group.id
  * }
  * ```
  *
@@ -47,24 +47,20 @@
  *   name        = "app"
  *   environment = "prod"
  *
- *   ecs_cluster_name              = "cluster-name"
- *   ecs_vpc_id                    = "${module.vpc.vpc_id}"
- *   ecs_subnet_ids                = "${module.vpc.private_subnets}"
+ *   ecs_cluster                   = aws_ecs_cluster.mycluster
+ *   ecs_vpc_id                    = module.vpc.vpc_id
+ *   ecs_subnet_ids                = module.vpc.private_subnets
  *   tasks_desired_count           = 2
  *   tasks_minimum_healthy_percent = 50
  *   tasks_maximum_percent         = 200
  *
  *   associate_nlb          = true
  *   nlb_subnet_cidr_blocks = ["10.0.0.0/24", "10.0.1.0/24", "10.0.2.0/24"]
- *   lb_target_group   = "${module.target_group.id}"
+ *   lb_target_group   = module.target_group.id
  * }
  * ```
  */
 
-data "aws_ecs_cluster" "main" {
-  cluster_name = "${var.ecs_cluster_name}"
-}
-
 locals {
   awslogs_group         = "${var.logs_cloudwatch_group == "" ? "/ecs/${var.environment}/${var.name}" : var.logs_cloudwatch_group}"
   target_container_name = "${var.target_container_name == "" ? "${var.name}-${var.environment}" : var.target_container_name}"
@@ -109,6 +105,7 @@ locals {
   }
 ]
 EOF
+
 }
 
 #
@@ -116,12 +113,12 @@ EOF
 #
 
 resource "aws_cloudwatch_log_group" "main" {
-  name              = "${local.awslogs_group}"
-  retention_in_days = "${var.logs_cloudwatch_retention}"
+  name              = local.awslogs_group
+  retention_in_days = var.logs_cloudwatch_retention
 
   tags = {
     Name        = "${var.name}-${var.environment}"
-    Environment = "${var.environment}"
+    Environment = var.environment
     Automation  = "Terraform"
   }
 }
@@ -131,7 +128,7 @@ resource "aws_cloudwatch_metric_alarm" "alarm_cpu" {
 
   alarm_name        = "${local.cloudwatch_alarm_name}-cpu"
   alarm_description = "Monitors ECS CPU Utilization"
-  alarm_actions     = ["${var.cloudwatch_alarm_actions}"]
+  alarm_actions     = var.cloudwatch_alarm_actions
 
   comparison_operator = "GreaterThanOrEqualToThreshold"
   evaluation_periods  = "2"
@@ -139,11 +136,11 @@ resource "aws_cloudwatch_metric_alarm" "alarm_cpu" {
   namespace           = "AWS/ECS"
   period              = "120"
   statistic           = "Average"
-  threshold           = "${var.cloudwatch_alarm_cpu_threshold}"
+  threshold           = var.cloudwatch_alarm_cpu_threshold
 
   dimensions = {
-    "ClusterName" = "${var.ecs_cluster_name}"
-    "ServiceName" = "${aws_ecs_service.main.name}"
+    "ClusterName" = var.ecs_cluster.name
+    "ServiceName" = aws_ecs_service.main[count.index].name
   }
 }
 
@@ -152,7 +149,7 @@ resource "aws_cloudwatch_metric_alarm" "alarm_mem" {
 
   alarm_name        = "${local.cloudwatch_alarm_name}-mem"
   alarm_description = "Monitors ECS CPU Utilization"
-  alarm_actions     = ["${var.cloudwatch_alarm_actions}"]
+  alarm_actions     = var.cloudwatch_alarm_actions
 
   comparison_operator = "GreaterThanOrEqualToThreshold"
   evaluation_periods  = "2"
@@ -160,11 +157,11 @@ resource "aws_cloudwatch_metric_alarm" "alarm_mem" {
   namespace           = "AWS/ECS"
   period              = "120"
   statistic           = "Average"
-  threshold           = "${var.cloudwatch_alarm_mem_threshold}"
+  threshold           = var.cloudwatch_alarm_mem_threshold
 
   dimensions = {
-    "ClusterName" = "${var.ecs_cluster_name}"
-    "ServiceName" = "${aws_ecs_service.main.name}"
+    "ClusterName" = var.ecs_cluster.name
+    "ServiceName" = aws_ecs_service.main[count.index].name
   }
 }
 
@@ -173,7 +170,7 @@ resource "aws_cloudwatch_metric_alarm" "alarm_cpu_no_lb" {
 
   alarm_name        = "${local.cloudwatch_alarm_name}-cpu"
   alarm_description = "Monitors ECS CPU Utilization"
-  alarm_actions     = ["${var.cloudwatch_alarm_actions}"]
+  alarm_actions     = var.cloudwatch_alarm_actions
 
   comparison_operator = "GreaterThanOrEqualToThreshold"
   evaluation_periods  = "2"
@@ -181,11 +178,11 @@ resource "aws_cloudwatch_metric_alarm" "alarm_cpu_no_lb" {
   namespace           = "AWS/ECS"
   period              = "120"
   statistic           = "Average"
-  threshold           = "${var.cloudwatch_alarm_cpu_threshold}"
+  threshold           = var.cloudwatch_alarm_cpu_threshold
 
   dimensions = {
-    "ClusterName" = "${var.ecs_cluster_name}"
-    "ServiceName" = "${aws_ecs_service.main_no_lb.name}"
+    "ClusterName" = var.ecs_cluster.name
+    "ServiceName" = aws_ecs_service.main_no_lb[count.index].name
   }
 }
 
@@ -194,7 +191,7 @@ resource "aws_cloudwatch_metric_alarm" "alarm_mem_no_lb" {
 
   alarm_name        = "${local.cloudwatch_alarm_name}-mem"
   alarm_description = "Monitors ECS CPU Utilization"
-  alarm_actions     = ["${var.cloudwatch_alarm_actions}"]
+  alarm_actions     = var.cloudwatch_alarm_actions
 
   comparison_operator = "GreaterThanOrEqualToThreshold"
   evaluation_periods  = "2"
@@ -202,11 +199,11 @@ resource "aws_cloudwatch_metric_alarm" "alarm_mem_no_lb" {
   namespace           = "AWS/ECS"
   period              = "120"
   statistic           = "Average"
-  threshold           = "${var.cloudwatch_alarm_mem_threshold}"
+  threshold           = var.cloudwatch_alarm_mem_threshold
 
   dimensions = {
-    "ClusterName" = "${var.ecs_cluster_name}"
-    "ServiceName" = "${aws_ecs_service.main_no_lb.name}"
+    "ClusterName" = var.ecs_cluster.name
+    "ServiceName" = aws_ecs_service.main_no_lb[count.index].name
   }
 }
 
@@ -217,18 +214,18 @@ resource "aws_cloudwatch_metric_alarm" "alarm_mem_no_lb" {
 resource "aws_security_group" "ecs_sg" {
   name        = "ecs-${var.name}-${var.environment}"
   description = "${var.name}-${var.environment} container security group"
-  vpc_id      = "${var.ecs_vpc_id}"
+  vpc_id      = var.ecs_vpc_id
 
   tags = {
     Name        = "ecs-${var.name}-${var.environment}"
-    Environment = "${var.environment}"
+    Environment = var.environment
     Automation  = "Terraform"
   }
 }
 
 resource "aws_security_group_rule" "app_ecs_allow_outbound" {
   description       = "All outbound"
-  security_group_id = "${aws_security_group.ecs_sg.id}"
+  security_group_id = aws_security_group.ecs_sg.id
 
   type        = "egress"
   from_port   = 0
@@ -238,55 +235,55 @@ resource "aws_security_group_rule" "app_ecs_allow_outbound" {
 }
 
 resource "aws_security_group_rule" "app_ecs_allow_https_from_alb" {
-  count = "${var.associate_alb}"
+  count = var.associate_alb ? 1 : 0
 
   description       = "Allow in ALB"
-  security_group_id = "${aws_security_group.ecs_sg.id}"
+  security_group_id = aws_security_group.ecs_sg.id
 
   type                     = "ingress"
-  from_port                = "${var.container_port}"
-  to_port                  = "${var.container_port}"
+  from_port                = var.container_port
+  to_port                  = var.container_port
   protocol                 = "tcp"
-  source_security_group_id = "${var.alb_security_group}"
+  source_security_group_id = var.alb_security_group
 }
 
 resource "aws_security_group_rule" "app_ecs_allow_health_check_from_alb" {
-  count = "${var.associate_alb > 0 && var.container_health_check_port > 0 ? 1 : 0}"
+  count = var.associate_alb && var.container_health_check_port > 0 ? 1 : 0
 
   description       = "Allow in health check from ALB"
-  security_group_id = "${aws_security_group.ecs_sg.id}"
+  security_group_id = aws_security_group.ecs_sg.id
 
   type                     = "ingress"
-  from_port                = "${var.container_health_check_port}"
-  to_port                  = "${var.container_health_check_port}"
+  from_port                = var.container_health_check_port
+  to_port                  = var.container_health_check_port
   protocol                 = "tcp"
-  source_security_group_id = "${var.alb_security_group}"
+  source_security_group_id = var.alb_security_group
 }
 
 resource "aws_security_group_rule" "app_ecs_allow_tcp_from_nlb" {
-  count = "${var.associate_nlb}"
+  count = var.associate_nlb ? 1 : 0
 
   description       = "Allow in NLB"
-  security_group_id = "${aws_security_group.ecs_sg.id}"
+  security_group_id = aws_security_group.ecs_sg.id
 
   type        = "ingress"
-  from_port   = "${var.container_port}"
-  to_port     = "${var.container_port}"
+  from_port   = var.container_port
+  to_port     = var.container_port
   protocol    = "tcp"
-  cidr_blocks = ["${var.nlb_subnet_cidr_blocks}"]
+  cidr_blocks = var.nlb_subnet_cidr_blocks
 }
 
 resource "aws_security_group_rule" "app_ecs_allow_health_check_from_nlb" {
-  count = "${var.associate_nlb > 0 && var.container_health_check_port > 0 ? 1 : 0}"
+  count = var.associate_nlb && var.container_health_check_port > 0 ? 1 : 0
 
   description       = "Allow in health check from NLB"
-  security_group_id = "${aws_security_group.ecs_sg.id}"
+  security_group_id = aws_security_group.ecs_sg.id
 
   type        = "ingress"
-  from_port   = "${var.container_health_check_port}"
-  to_port     = "${var.container_health_check_port}"
+  from_port   = var.container_health_check_port
+  to_port     = var.container_health_check_port
   protocol    = "tcp"
-  cidr_blocks = ["${var.nlb_subnet_cidr_blocks}"]
+  cidr_blocks = var.nlb_subnet_cidr_blocks
 }
 
 #
@@ -294,7 +291,7 @@ resource "aws_security_group_rule" "app_ecs_allow_health_check_from_nlb" {
 #
 
 data "aws_iam_policy_document" "instance_role_policy_doc" {
-  count = "${var.ecs_instance_role != "" ? 1 : 0}"
+  count = var.ecs_instance_role != "" ? 1 : 0
 
   statement {
     actions = [
@@ -303,7 +300,7 @@ data "aws_iam_policy_document" "instance_role_policy_doc" {
       "ecs:Submit*",
     ]
 
-    resources = ["${data.aws_ecs_cluster.main.arn}"]
+    resources = [var.ecs_cluster.arn]
   }
 
   statement {
@@ -316,7 +313,7 @@ data "aws_iam_policy_document" "instance_role_policy_doc" {
     condition {
       test     = "StringEquals"
       variable = "ecs:cluster"
-      values   = ["${data.aws_ecs_cluster.main.arn}"]
+      values   = [var.ecs_cluster.arn]
     }
   }
 
@@ -336,7 +333,7 @@ data "aws_iam_policy_document" "instance_role_policy_doc" {
       "logs:PutLogEvents",
     ]
 
-    resources = ["${aws_cloudwatch_log_group.main.arn}"]
+    resources = [aws_cloudwatch_log_group.main.arn]
   }
 
   statement {
@@ -354,16 +351,16 @@ data "aws_iam_policy_document" "instance_role_policy_doc" {
       "ecr:BatchGetImage",
     ]
 
-    resources = ["${var.ecr_repo_arns}"]
+    resources = var.ecr_repo_arns
   }
 }
 
 resource "aws_iam_role_policy" "instance_role_policy" {
-  count = "${var.ecs_instance_role != "" ? 1 : 0}"
+  count = var.ecs_instance_role != "" ? 1 : 0
 
   name   = "${var.ecs_instance_role}-policy"
-  role   = "${var.ecs_instance_role}"
-  policy = "${data.aws_iam_policy_document.instance_role_policy_doc.json}"
+  role   = var.ecs_instance_role
+  policy = data.aws_iam_policy_document.instance_role_policy_doc[0].json
 }
 
 #
@@ -388,7 +385,7 @@ data "aws_iam_policy_document" "task_execution_role_policy_doc" {
       "logs:PutLogEvents",
     ]
 
-    resources = ["${aws_cloudwatch_log_group.main.arn}"]
+    resources = [aws_cloudwatch_log_group.main.arn]
   }
 
   statement {
@@ -406,70 +403,71 @@ data "aws_iam_policy_document" "task_execution_role_policy_doc" {
       "ecr:BatchGetImage",
     ]
 
-    resources = ["${var.ecr_repo_arns}"]
+    resources = var.ecr_repo_arns
   }
 }
 
 resource "aws_iam_role" "task_role" {
   name               = "ecs-task-role-${var.name}-${var.environment}"
-  assume_role_policy = "${data.aws_iam_policy_document.ecs_assume_role_policy.json}"
+  assume_role_policy = data.aws_iam_policy_document.ecs_assume_role_policy.json
 }
 
 resource "aws_iam_role" "task_execution_role" {
-  count = "${var.ecs_use_fargate ? 1 : 0}"
+  count = var.ecs_use_fargate ? 1 : 0
 
   name               = "ecs-task-execution-role-${var.name}-${var.environment}"
-  assume_role_policy = "${data.aws_iam_policy_document.ecs_assume_role_policy.json}"
+  assume_role_policy = data.aws_iam_policy_document.ecs_assume_role_policy.json
 }
 
 resource "aws_iam_role_policy" "task_execution_role_policy" {
-  count = "${var.ecs_use_fargate ? 1 : 0}"
+  count = var.ecs_use_fargate ? 1 : 0
 
-  name   = "${aws_iam_role.task_execution_role.name}-policy"
-  role   = "${aws_iam_role.task_execution_role.name}"
-  policy = "${data.aws_iam_policy_document.task_execution_role_policy_doc.json}"
+  name   = "${aws_iam_role.task_execution_role[0].name}-policy"
+  role   = aws_iam_role.task_execution_role[0].name
+  policy = data.aws_iam_policy_document.task_execution_role_policy_doc.json
 }
 
 #
 # ECS
 #
 
-data "aws_region" "current" {}
+data "aws_region" "current" {
+}
 
 # Create a task definition with a golang image so the ecs service can be easily
 # tested. We expect deployments will manage the future container definitions.
 resource "aws_ecs_task_definition" "main" {
   family        = "${var.name}-${var.environment}"
   network_mode  = "awsvpc"
-  task_role_arn = "${aws_iam_role.task_role.arn}"
+  task_role_arn = aws_iam_role.task_role.arn
 
   # Fargate requirements
-  requires_compatibilities = "${compact(list(var.ecs_use_fargate ? "FARGATE" : ""))}"
-  cpu                      = "${var.ecs_use_fargate ? var.fargate_task_cpu : ""}"
-  memory                   = "${var.ecs_use_fargate ? var.fargate_task_memory : ""}"
-  execution_role_arn       = "${join("", aws_iam_role.task_execution_role.*.arn)}"
+  requires_compatibilities = compact([var.ecs_use_fargate ? "FARGATE" : ""])
+  cpu                      = var.ecs_use_fargate ? var.fargate_task_cpu : ""
+  memory                   = var.ecs_use_fargate ? var.fargate_task_memory : ""
+  execution_role_arn       = join("", aws_iam_role.task_execution_role.*.arn)
 
-  container_definitions = "${var.container_definitions == "" ? local.default_container_definitions : var.container_definitions}"
+  container_definitions = var.container_definitions == "" ? local.default_container_definitions : var.container_definitions
 
   lifecycle {
     ignore_changes = [
-      "requires_compatibilities",
-      "cpu",
-      "memory",
-      "execution_role_arn",
-      "container_definitions",
+      requires_compatibilities,
+      cpu,
+      memory,
+      execution_role_arn,
+      container_definitions,
     ]
   }
 }
 
 # Create a data source to pull the latest active revision from
 data "aws_ecs_task_definition" "main" {
-  task_definition = "${aws_ecs_task_definition.main.family}"
-  depends_on      = ["aws_ecs_task_definition.main"]         # ensures at least one task def exists
+  task_definition = aws_ecs_task_definition.main.family
+  depends_on      = [aws_ecs_task_definition.main] # ensures at least one task def exists
 }
 
 locals {
-  ecs_service_launch_type = "${var.ecs_use_fargate ? "FARGATE" : "EC2"}"
+  ecs_service_launch_type = var.ecs_use_fargate ? "FARGATE" : "EC2"
 
   ecs_service_ordered_placement_strategy = {
     EC2 = [
@@ -482,86 +480,119 @@ locals {
         field = "instanceId"
       },
     ]
-
     FARGATE = []
   }
 
   ecs_service_placement_constraints = {
-    EC2 = [{
-      type = "distinctInstance"
-    }]
-
+    EC2 = [
+      {
+        type = "distinctInstance"
+      },
+    ]
     FARGATE = []
   }
 }
 
 resource "aws_ecs_service" "main" {
-  count = "${var.associate_alb || var.associate_nlb ? 1 : 0}"
+  count = var.associate_alb || var.associate_nlb ? 1 : 0
 
-  name    = "${var.name}"
-  cluster = "${data.aws_ecs_cluster.main.arn}"
+  name    = var.name
+  cluster = var.ecs_cluster.arn
 
-  launch_type = "${local.ecs_service_launch_type}"
+  launch_type = local.ecs_service_launch_type
 
   # Use latest active revision
   task_definition = "${aws_ecs_task_definition.main.family}:${max(
-    "${aws_ecs_task_definition.main.revision}",
-  "${data.aws_ecs_task_definition.main.revision}")}"
+    aws_ecs_task_definition.main.revision,
+    data.aws_ecs_task_definition.main.revision,
+  )}"
 
-  desired_count                      = "${var.tasks_desired_count}"
-  deployment_minimum_healthy_percent = "${var.tasks_minimum_healthy_percent}"
-  deployment_maximum_percent         = "${var.tasks_maximum_percent}"
+  desired_count                      = var.tasks_desired_count
+  deployment_minimum_healthy_percent = var.tasks_minimum_healthy_percent
+  deployment_maximum_percent         = var.tasks_maximum_percent
 
-  ordered_placement_strategy = "${local.ecs_service_ordered_placement_strategy[local.ecs_service_launch_type]}"
-  placement_constraints      = "${local.ecs_service_placement_constraints[local.ecs_service_launch_type]}"
+  dynamic ordered_placement_strategy {
+    for_each = local.ecs_service_ordered_placement_strategy[local.ecs_service_launch_type]
+
+    content {
+      type  = ordered_placement_strategy.value.type
+      field = ordered_placement_strategy.value.field
+    }
+  }
+
+  dynamic placement_constraints {
+    for_each = local.ecs_service_placement_constraints[local.ecs_service_launch_type]
+
+    content {
+      type = placement_constraints.value.type
+    }
+  }
 
   network_configuration {
-    subnets          = ["${var.ecs_subnet_ids}"]
-    security_groups  = ["${aws_security_group.ecs_sg.id}"]
+    subnets          = var.ecs_subnet_ids
+    security_groups  = [aws_security_group.ecs_sg.id]
     assign_public_ip = false
   }
 
   load_balancer {
-    target_group_arn = "${var.lb_target_group}"
-    container_name   = "${local.target_container_name}"
-    container_port   = "${var.container_port}"
+    target_group_arn = var.lb_target_group
+    container_name   = local.target_container_name
+    container_port   = var.container_port
   }
 
   lifecycle {
-    ignore_changes = ["task_definition"]
+    ignore_changes = [task_definition]
   }
 }
 
-# XXX: We have to duplicate this resource with a count instead of parameterizing
+# NOTE: We have to duplicate this resource with a count instead of parameterizing
 # the load_balancer argument due to this Terraform bug:
 # https://github.com/hashicorp/terraform/issues/16856
 resource "aws_ecs_service" "main_no_lb" {
-  count = "${var.associate_alb || var.associate_nlb ? 0 : 1}"
+  count = var.associate_alb || var.associate_nlb ? 0 : 1
 
-  name    = "${var.name}"
-  cluster = "${data.aws_ecs_cluster.main.arn}"
+  name    = var.name
+  cluster = var.ecs_cluster.arn
 
-  launch_type = "${local.ecs_service_launch_type}"
+  launch_type = local.ecs_service_launch_type
 
   # Use latest active revision
   task_definition = "${aws_ecs_task_definition.main.family}:${max(
-    "${aws_ecs_task_definition.main.revision}",
-  "${data.aws_ecs_task_definition.main.revision}")}"
+    aws_ecs_task_definition.main.revision,
+    data.aws_ecs_task_definition.main.revision,
+  )}"
+
+  desired_count                      = var.tasks_desired_count
+  deployment_minimum_healthy_percent = var.tasks_minimum_healthy_percent
+  deployment_maximum_percent         = var.tasks_maximum_percent
+
+  dynamic ordered_placement_strategy {
+    for_each = local.ecs_service_ordered_placement_strategy[local.ecs_service_launch_type]
+    #    for_each = var.ecs_use_fargate ? [] : ["attribute:ecs.availability-zone", "instanceId"]
 
-  desired_count                      = "${var.tasks_desired_count}"
-  deployment_minimum_healthy_percent = "${var.tasks_minimum_healthy_percent}"
-  deployment_maximum_percent         = "${var.tasks_maximum_percent}"
+    content {
+      type  = ordered_placement_strategy.value.type
+      field = ordered_placement_strategy.value.field
+    }
+  }
+
+  dynamic placement_constraints {
+    for_each = local.ecs_service_placement_constraints[local.ecs_service_launch_type]
+    #    for_each = var.ecs_use_fargate ? [] : ["distinctInstance"]
 
-  ordered_placement_strategy = "${local.ecs_service_ordered_placement_strategy[local.ecs_service_launch_type]}"
-  placement_constraints      = "${local.ecs_service_placement_constraints[local.ecs_service_launch_type]}"
+    content {
+      type = placement_constraints.value.type
+    }
+  }
 
   network_configuration {
-    subnets          = ["${var.ecs_subnet_ids}"]
-    security_groups  = ["${aws_security_group.ecs_sg.id}"]
+    subnets          = var.ecs_subnet_ids
+    security_groups  = aws_security_group.ecs_sg.id
     assign_public_ip = false
   }
 
   lifecycle {
-    ignore_changes = ["task_definition"]
+    ignore_changes = [task_definition]
   }
 }
+
diff --git a/outputs.tf b/outputs.tf
index f477cf3..c98b233 100644
--- a/outputs.tf
+++ b/outputs.tf
@@ -1,39 +1,40 @@
 output "ecs_security_group_id" {
   description = "Security Group ID assigned to the ECS tasks."
-  value       = "${aws_security_group.ecs_sg.id}"
+  value       = aws_security_group.ecs_sg.id
 }
 
 output "task_execution_role_arn" {
   description = "The ARN of the task execution role that the Amazon ECS container agent and the Docker daemon can assume."
-  value       = "${join("", aws_iam_role.task_execution_role.*.arn)}"
+  value       = join("", aws_iam_role.task_execution_role.*.arn)
 }
 
 output "task_role_arn" {
   description = "The ARN of the IAM role assumed by Amazon ECS container tasks."
-  value       = "${aws_iam_role.task_role.arn}"
+  value       = aws_iam_role.task_role.arn
 }
 
 output "task_role_name" {
   description = "The name of the IAM role assumed by Amazon ECS container tasks."
-  value       = "${aws_iam_role.task_role.name}"
+  value       = aws_iam_role.task_role.name
 }
 
 output "task_definition_arn" {
   description = "Full ARN of the Task Definition (including both family and revision)."
-  value       = "${aws_ecs_task_definition.main.arn}"
+  value       = aws_ecs_task_definition.main.arn
 }
 
 output "task_definition_family" {
   description = "The family of the Task Definition."
-  value       = "${aws_ecs_task_definition.main.family}"
+  value       = aws_ecs_task_definition.main.family
 }
 
 output "awslogs_group" {
   description = "Name of the CloudWatch Logs log group containers should use."
-  value       = "${local.awslogs_group}"
+  value       = local.awslogs_group
 }
 
 output "awslogs_group_arn" {
   description = "ARN of the CloudWatch Logs log group containers should use."
-  value       = "${aws_cloudwatch_log_group.main.arn}"
+  value       = aws_cloudwatch_log_group.main.arn
 }
+
diff --git a/variables.tf b/variables.tf
index b9a9097..293144c 100644
--- a/variables.tf
+++ b/variables.tf
@@ -1,11 +1,11 @@
 variable "name" {
   description = "The service name."
-  type        = "string"
+  type        = string
 }
 
 variable "environment" {
   description = "Environment tag, e.g prod."
-  type        = "string"
+  type        = string
 }
 
 variable "cloudwatch_alarm_name" {
@@ -47,134 +47,138 @@ variable "cloudwatch_alarm_mem_threshold" {
 variable "logs_cloudwatch_retention" {
   description = "Number of days you want to retain log events in the log group."
   default     = 90
-  type        = "string"
+  type        = string
 }
 
 variable "logs_cloudwatch_group" {
   description = "CloudWatch log group to create and use. Default: /ecs/{name}-{environment}"
   default     = ""
-  type        = "string"
+  type        = string
 }
 
 variable "ecr_repo_arns" {
   description = "The ARNs of the ECR repos.  By default, allows all repositories."
-  type        = "list"
+  type        = list(string)
   default     = ["*"]
 }
 
 variable "ecs_use_fargate" {
   description = "Whether to use Fargate for the task definition."
   default     = false
-  type        = "string"
+  type        = string
 }
 
-variable "ecs_cluster_name" {
-  description = "The name  of the ECS cluster."
-  type        = "string"
+variable "ecs_cluster" {
+  description = "ECS cluster object for this task."
+  type = object({
+    arn  = string
+    name = string
+  })
 }
 
 variable "ecs_instance_role" {
   description = "The name of the ECS instance role."
   default     = ""
-  type        = "string"
+  type        = string
 }
 
 variable "ecs_vpc_id" {
   description = "VPC ID to be used by ECS."
-  type        = "string"
+  type        = string
 }
 
 variable "ecs_subnet_ids" {
   description = "Subnet IDs for the ECS tasks."
-  type        = "list"
+  type        = list(string)
 }
 
 variable "fargate_task_cpu" {
   description = "Number of cpu units used in initial task definition. Default is minimum."
   default     = 256
-  type        = "string"
+  type        = string
 }
 
 variable "fargate_task_memory" {
   description = "Amount (in MiB) of memory used in initial task definition. Default is minimum."
   default     = 512
-  type        = "string"
+  type        = string
 }
 
 variable "tasks_desired_count" {
   description = "The number of instances of a task definition."
   default     = 1
-  type        = "string"
+  type        = string
 }
 
 variable "tasks_minimum_healthy_percent" {
   description = "Lower limit on the number of running tasks."
   default     = "100"
-  type        = "string"
+  type        = string
 }
 
 variable "tasks_maximum_percent" {
   description = "Upper limit on the number of running tasks."
   default     = "200"
-  type        = "string"
+  type        = string
 }
 
 variable "container_image" {
   description = "The image of the container."
   default     = "golang:1.12.5-alpine"
-  type        = "string"
+  type        = string
 }
 
 variable "container_port" {
   description = "The port on which the container will receive traffic."
   default     = 80
-  type        = "string"
+  type        = string
 }
 
 variable "container_health_check_port" {
   description = "An additional port on which the container can receive a health check.  Zero means the container port can only receive a health check on the port set by the container_port variable."
   default     = 0
-  type        = "string"
+  type        = string
 }
 
 variable "container_definitions" {
   description = "Container definitions provided as valid JSON document. Default uses golang:1.12.5-alpine running a simple hello world."
   default     = ""
-  type        = "string"
+  type        = string
 }
 
 variable "target_container_name" {
   description = "Name of the container the Load Balancer should target. Default: {name}-{environment}"
   default     = ""
-  type        = "string"
+  type        = string
 }
 
 variable "associate_alb" {
   description = "Whether to associate an Application Load Balancer (ALB) with the ECS service."
   default     = false
-  type        = "string"
+  type        = string
 }
 
 variable "associate_nlb" {
   description = "Whether to associate a Network Load Balancer (NLB) with the ECS service."
   default     = false
-  type        = "string"
+  type        = string
 }
 
 variable "alb_security_group" {
   description = "Application Load Balancer (ALB) security group ID to allow traffic from."
   default     = ""
-  type        = "string"
+  type        = string
 }
 
 variable "lb_target_group" {
   description = "Either Application Load Balancer (ALB) or Network Load Balancer (NLB) target group ARN tasks will register with."
   default     = ""
-  type        = "string"
+  type        = string
 }
 
 variable "nlb_subnet_cidr_blocks" {
   description = "List of Network Load Balancer (NLB) CIDR blocks to allow traffic from."
   default     = []
-  type        = "list"
+  type        = list(string)
 }
+