inframain.tf

...

module "google_kubernetes_cluster" {
  source = "./kubernetes_cluster"

  project_id                 = var.project_id
  region                     = var.region
  node_zones                 = var.cluster_node_zones
  service_account            = var.service_account
  network_name               = module.google_networks.network.name
  subnet_name                = module.google_networks.subnet.name
  master_ipv4_cidr_block     = module.google_networks.cluster_master_ip_cidr_range
  pods_ipv4_cidr_block       = module.google_networks.cluster_pods_ip_cidr_range
  services_ipv4_cidr_block   = module.google_networks.cluster_services_ip_cidr_range
  authorized_ipv4_cidr_block = "${module.bastion.ip}/32"
}

...