Allow using multiple target groups.

Get rid of the service IAM role.

Author: Eugene Dementiev

data.tf

@@ -6,7 +6,7 @@ data "aws_region" "current" {}
 
 
 data "aws_lb_target_group" "TG" {
-  count = local.balanced ? 1 : 0
+  count = local.balanced ? length(local.target_group_names) : 0
 
-  name = local.target_group_name
+  name = local.target_group_names[count.index]
 }

iam.tf

@@ -29,8 +29,6 @@ resource "aws_ecs_service" "service" {
   deployment_minimum_healthy_percent = var.deployment_minimum_healthy_percent
   deployment_maximum_percent         = var.deployment_maximum_percent
 
-  iam_role = local.balanced ? aws_iam_role.task-role-alb[0].arn : ""
-
   ordered_placement_strategy {
     type  = "spread"
     field = "attribute:ecs.availability-zone"
@@ -42,10 +40,10 @@ resource "aws_ecs_service" "service" {
   }
 
   dynamic "load_balancer" {
-    for_each = local.balanced ? [1] : []
+    for_each = local.balanced ? data.aws_lb_target_group.TG[*].arn : []
 
     content {
-      target_group_arn = data.aws_lb_target_group.TG[0].arn
+      target_group_arn = load_balancer.value
       container_name   = var.service_name
       container_port   = var.container_port
     }

main.tf

@@ -11,6 +11,11 @@ variable "target_group_name" {
   default     = ""
 }
 
+variable "target_group_names" {
+  description = "Names of the ALB target groups. Defaults to the `[cluster_name]` if not set"
+  default     = []
+}
+
 variable "environment" {
   description = "Enviropnment vars to pass to the container. Note: they will be visible in the task definition, so please don't pass any secrets here."
   type        = map
@@ -80,8 +85,9 @@ variable "desired_count" {
 }
 
 locals {
-  balanced          = var.container_port > 0
-  target_group_name = coalesce(var.target_group_name, var.cluster_name)
+  balanced = var.container_port > 0
+
+  target_group_names = coalescelist(distinct(compact(concat(var.target_group_names, list(var.target_group_name)))), list(var.cluster_name))
 
   default_log_configuration = {
     "logDriver" = "awslogs"