Add support for setting node pool metadata key/value pairs.

.gitignore

@@ -19,6 +19,9 @@
 Session.vim
 .netrwhist
 
+# IntelliJ IDEA files:
+.idea/
+
 ### https://raw.github.com/github/gitignore/90f149de451a5433aebd94d02d11b0e28843a1af/Terraform.gitignore
 
 # Local .terraform directories

README.md

@@ -52,6 +52,14 @@ module "gke" {
     }
   }
 
+  node_pools_metadata = {
+    all = {}
+
+    default-node-pool = {
+      shutdown-script = "${file(var.kube_shutdown_script)}"
+    }
+  }
+
   node_pools_taints = {
     all = []
 
@@ -108,6 +116,7 @@ Then perform the following commands on the root folder:
 | network_project_id | The project ID of the shared VPC's host (for shared vpc support) | string | `` | no |
 | node_pools | List of maps containing node pools | list | `<list>` | no |
 | node_pools_labels | Map of maps containing node labels by node-pool name | map | `<map>` | no |
+| node_pools_metadata | Map of maps containing node metadata by node-pool name | map | `<map>` | no |
 | node_pools_tags | Map of lists containing node network tags by node-pool name | map | `<map>` | no |
 | node_pools_taints | Map of lists containing node taints by node-pool name | map | `<map>` | no |
 | node_version | The Kubernetes version of the node pools. Defaults kubernetes_version (master) variable and can be overridden for individual node pools by setting the `version` key on them. Must be empyty or set the same as master at cluster creation. | string | `` | no |

cluster_regional.tf

@@ -109,6 +109,7 @@ resource "google_container_node_pool" "pools" {
     image_type   = "${lookup(var.node_pools[count.index], "image_type", "COS")}"
     machine_type = "${lookup(var.node_pools[count.index], "machine_type", "n1-standard-2")}"
     labels       = "${merge(map("cluster_name", var.name), map("node_pool", lookup(var.node_pools[count.index], "name")), var.node_pools_labels["all"], var.node_pools_labels[lookup(var.node_pools[count.index], "name")])}"
+    metadata     = "${merge(map("cluster_name", var.name), map("node_pool", lookup(var.node_pools[count.index], "name")), var.node_pools_metadata["all"], var.node_pools_metadata[lookup(var.node_pools[count.index], "name")])}"
     taint        = "${concat(var.node_pools_taints["all"], var.node_pools_taints[lookup(var.node_pools[count.index], "name")])}"
     tags         = "${concat(list("gke-${var.name}"), list("gke-${var.name}-${lookup(var.node_pools[count.index], "name")}"), var.node_pools_tags["all"], var.node_pools_tags[lookup(var.node_pools[count.index], "name")])}"
 

cluster_zonal.tf

@@ -109,6 +109,7 @@ resource "google_container_node_pool" "zonal_pools" {