fix: Allow for both Fargate and EC2/Autoscaling capacity providers in same cluster (#69)

Author: bryantbiggs

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/antonbabenko/pre-commit-terraform
-    rev: v1.73.0
+    rev: v1.74.1
     hooks:
       - id: terraform_fmt
       - id: terraform_validate

README.md

@@ -231,6 +231,7 @@ No modules.
 | <a name="input_cluster_name"></a> [cluster\_name](#input\_cluster\_name) | Name of the cluster (up to 255 letters, numbers, hyphens, and underscores) | `string` | `""` | no |
 | <a name="input_cluster_settings"></a> [cluster\_settings](#input\_cluster\_settings) | Configuration block(s) with cluster settings. For example, this can be used to enable CloudWatch Container Insights for a cluster | `map(string)` | <pre>{<br>  "name": "containerInsights",<br>  "value": "enabled"<br>}</pre> | no |
 | <a name="input_create"></a> [create](#input\_create) | Determines whether resources will be created (affects all resources) | `bool` | `true` | no |
+| <a name="input_default_capacity_provider_use_fargate"></a> [default\_capacity\_provider\_use\_fargate](#input\_default\_capacity\_provider\_use\_fargate) | Determines whether to use Fargate or autoscaling for default capacity provider strategy | `bool` | `true` | no |
 | <a name="input_fargate_capacity_providers"></a> [fargate\_capacity\_providers](#input\_fargate\_capacity\_providers) | Map of Fargate capacity provider definitions to use for the cluster | `any` | `{}` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | A map of tags to add to all resources | `map(string)` | `{}` | no |
 

examples/complete/main.tf

@@ -42,6 +42,14 @@ module "ecs" {
     }
   }
 
+  default_capacity_provider_use_fargate = false
+
+  # Capacity provider - Fargate
+  fargate_capacity_providers = {
+    FARGATE      = {}
+    FARGATE_SPOT = {}
+  }
+
   # Capacity provider - autoscaling groups
   autoscaling_capacity_providers = {
     one = {

main.tf

@@ -51,18 +51,14 @@ resource "aws_ecs_cluster" "this" {
 ################################################################################
 
 locals {
-  # We are merging these together so that we can reference the ECS capacity provider
-  # (ec2 autoscaling) created in this module below. Fargate is easy since its just
-  # static values, but the autoscaling cappacity provider needs to be self-referenced from
-  # within this module
-  cluster_capacity_providers = merge(
-    var.fargate_capacity_providers,
-    { for k, v in var.autoscaling_capacity_providers : k => merge(aws_ecs_capacity_provider.this[k], v) }
+  default_capacity_providers = merge(
+    { for k, v in var.fargate_capacity_providers : k => v if var.default_capacity_provider_use_fargate },
+    { for k, v in var.autoscaling_capacity_providers : k => v if !var.default_capacity_provider_use_fargate }
   )
 }
 
 resource "aws_ecs_cluster_capacity_providers" "this" {
-  count = var.create ? 1 : 0
+  count = var.create && length(merge(var.fargate_capacity_providers, var.autoscaling_capacity_providers)) > 0 ? 1 : 0
 
   cluster_name = aws_ecs_cluster.this[0].name
   capacity_providers = distinct(concat(
@@ -71,7 +67,7 @@ resource "aws_ecs_cluster_capacity_providers" "this" {
   ))
 
   dynamic "default_capacity_provider_strategy" {
-    for_each = local.cluster_capacity_providers
+    for_each = local.default_capacity_providers
     iterator = strategy
 
     content {
@@ -80,6 +76,10 @@ resource "aws_ecs_cluster_capacity_providers" "this" {
       weight            = try(strategy.value.default_capacity_provider_strategy.weight, null)
     }
   }
+
+  depends_on = [
+    aws_ecs_capacity_provider.this
+  ]
 }
 
 ################################################################################

variables.tf

@@ -39,6 +39,12 @@ variable "cluster_settings" {
 # Capacity Providers
 ################################################################################
 
+variable "default_capacity_provider_use_fargate" {
+  description = "Determines whether to use Fargate or autoscaling for default capacity provider strategy"
+  type        = bool
+  default     = true
+}
+
 variable "fargate_capacity_providers" {
   description = "Map of Fargate capacity provider definitions to use for the cluster"
   type        = any