feat: Add a homemade depends_on for MNG submodule to ensure ordering of resource creation (#867)

modules/node_groups/README.md

@@ -52,6 +52,7 @@ No requirements.
 | cluster\_name | Name of parent cluster | `string` | n/a | yes |
 | create\_eks | Controls if EKS resources should be created (it affects almost all resources) | `bool` | `true` | no |
 | default\_iam\_role\_arn | ARN of the default IAM worker role to use if one is not specified in `var.node_groups` or `var.node_groups_defaults` | `string` | n/a | yes |
+| ng\_depends\_on | List of references to other resources this submodule depends on | `any` | `null` | no |
 | node\_groups | Map of maps of `eks_node_groups` to create. See "`node_groups` and `node_groups_defaults` keys" section in README.md for more details | `any` | `{}` | no |
 | node\_groups\_defaults | map of maps of node groups to create. See "`node_groups` and `node_groups_defaults` keys" section in README.md for more details | `any` | n/a | yes |
 | tags | A map of tags to add to all resources | `map(string)` | n/a | yes |

modules/node_groups/node_groups.tf

@@ -47,4 +47,6 @@ resource "aws_eks_node_group" "workers" {
     create_before_destroy = true
     ignore_changes        = [scaling_config.0.desired_size]
   }
+
+  depends_on = [var.ng_depends_on]
 }

modules/node_groups/random.tf

@@ -18,4 +18,6 @@ resource "random_pet" "node_groups" {
     subnet_ids      = join("|", each.value["subnets"])
     node_group_name = join("-", [var.cluster_name, each.key])
   }
+
+  depends_on = [var.ng_depends_on]
 }

modules/node_groups/variables.tf

@@ -34,3 +34,11 @@ variable "node_groups" {
   type        = any
   default     = {}
 }
+
+# Hack for a homemade `depends_on` https://discuss.hashicorp.com/t/tips-howto-implement-module-depends-on-emulation/2305/2
+# Will be removed in Terraform 0.13 with the support of module's `depends_on` https://github.com/hashicorp/terraform/issues/10462
+variable "ng_depends_on" {
+  description = "List of references to other resources this submodule depends on"
+  type        = any
+  default     = null
+}