Allow additional linked containers

Author: Eugene Dementiev

main.tf

@@ -1,20 +1,27 @@
 resource "aws_ecs_task_definition" "task" {
   family = "${var.cluster_name}-${var.service_name}"
-  container_definitions = jsonencode([
+  container_definitions = jsonencode([for s in concat([
     {
       name              = var.service_name
       image             = var.image
       cpu               = var.cpu
       essential         = var.essential
       memory            = var.memory
       memoryReservation = var.memory_reservation
-      portMappings      = local.balanced ? coalescelist(var.port_mappings, local.defaultPortMappings) : []
       mountPoints       = []
-      logConfiguration  = local.log_configuration
-      environment       = [for k in sort(keys(var.environment)) : { "name" : k, "value" : var.environment[k] }]
       volumesFrom       = []
     }
-  ])
+    ], var.additional_container_definitions) : merge(s, {
+    environment = [for k in sort(keys(var.environment)) : { "name" : k, "value" : var.environment[k] }]
+    # leverage the new terraform syntax and override the awslogs-stream-prefix
+    logConfiguration = merge(local.log_configuration,
+      local.log_configuration["logDriver"] == "awslogs" && local.log_configuration["options"] != null ? {
+        options = merge(local.log_configuration["options"], { "awslogs-stream-prefix" = s.name })
+      } : {}
+    )
+    # load balancer the local.load_balancer_container_name
+    portMappings = local.balanced && local.load_balancer_container_name == s.name ? coalescelist(var.port_mappings, local.defaultPortMappings) : []
+  })])
 
   task_role_arn = var.task_role_arn
 
@@ -44,7 +51,7 @@ resource "aws_ecs_service" "service" {
 
     content {
       target_group_arn = load_balancer.value
-      container_name   = var.service_name
+      container_name   = local.load_balancer_container_name
       container_port   = var.container_port
     }
   }

variables.tf

@@ -52,6 +52,17 @@ variable "container_port" {
   default = 0
 }
 
+variable "load_balancer_container_name" {
+  description = "Name of the container that will used by the load balancer. Can be used to put nginx proxy in front of the app. Defaults to the service name"
+  type        = string
+  default     = ""
+}
+
+variable "additional_container_definitions" {
+  type    = list(any)
+  default = []
+}
+
 variable "task_role_arn" {
   type    = string
   default = ""
@@ -85,7 +96,8 @@ variable "desired_count" {
 }
 
 locals {
-  balanced = var.container_port > 0
+  balanced                     = var.container_port > 0
+  load_balancer_container_name = coalesce(var.load_balancer_container_name, var.service_name)
 
   target_group_names = coalescelist(distinct(compact(concat(var.target_group_names, list(var.target_group_name)))), list(var.cluster_name))