Destroying and re-creating dependent Terraform modules when their parent changes

[zackproser]

A user asked:

Hi. We are trying to recreate worker node on calico cni-updates. Is it possible to destroy and recreate the worker node module on parent module changes?

module "calico_cni" {
  source = "../../modules/calico-cni"
  cluster_kubeconfig = module.control_plane.eks_kubeconfig
}

module "cluster_workers" {
  source                       = "../../modules/cluster-creation/cluster-workers"
  depends_on                   = [module.calico_cni]
  cf_vpc_stack                 = var.cf_vpc_stack
  eks_certificate_authority    = module.control_plane.eks_cluster_certificate_authority
  eks_cluster_endpoint         = module.control_plane.eks_cluster_endpoint
  eks_cluster_name             = module.control_plane.eks_cluster_name
  node_group_configurations    = var.node_group_configurations
  workers_ami_id               = var.ami_id
  workers_instance_type        = var.instance_type
  workers_ssm_arn              = module.iam_roles.worker_nodes_ssm_policy_arn
  cluster_kubeconfig           = module.control_plane.eks_kubeconfig
  wait_for_kube_system_timeout = var.wait_for_kube_system_timeout
}

[zackproser]

The best way to achieve this would be to set, for example, a name parameter in your child module (such as the worker_name_prefix) in our eks workers module) to the version of CNI - or something similar that will change everytime that CNI is deployed.

This way, Terraform will consider the name change a destructive and backward incompatible change, causing the dependent resources to be destroyed and re-created as you intend.