add options for fleet registration and feature enablement

Author: Sam Naser

docs/upgrading_to_v20.0.md

@@ -17,13 +17,13 @@ an installation performed with the old module to using the new module. **NOTE:**
 There should be two ASM revisions present at this point (in-cluster or managed, depending on whether the previous installation was managed). Now,
 we must perform a canary upgrade to move workloads onto the new ASM revision. To do this:
 
-1. Relabel namespaces to use the revision label from the managed revision (either `asm-managed`, `asm-managed-stable`, or `asm-managed-rapid`)
+1. Relabel namespaces to use the revision label from the managed revision (`asm-managed`, `asm-managed-stable`, or `asm-managed-rapid`)
 2. Rollout workloads in those namespaces to get them onto the new ASM version
 3. [Optional] Remove the previous revision with `istioctl x uninstall --revision ...` (if the previous installation was in-cluster)
 
 
 #### Migrating options
 
-Another difference from the previous module is that the new ASM module does not provide variables option configuration (i.e. `custom_overlay`, `options`). These should be managed separately
+Another difference from the previous module is that the new ASM module does not provide variables for option configuration (e.g. `custom_overlay`, `options`). For the new version these should be managed separately
 outside the module. This is because those options were tightly coupled to pulling down an installer which the new module does not do. To use options specified in the previous module with the new module find the corresponding configuration [here](https://github.com/GoogleCloudPlatform/anthos-service-mesh-packages/tree/main/asm/istio/options) and move the
-config to the mesh configuration for the revision.
+config to the mesh configuration for the managed revision.

modules/asm/README.md

@@ -35,6 +35,8 @@ To deploy this config:
 | cluster\_location | The cluster location for this ASM installation. | `string` | n/a | yes |
 | cluster\_name | The unique name to identify the cluster in ASM. | `string` | n/a | yes |
 | enable\_cni | Determines whether to enable CNI for this ASM installation. Required to use Managed Data Plane (MDP). | `bool` | `false` | no |
+| enable\_fleet\_registration | Determines whether the module enables the mesh feature on the fleet. | `bool` | `false` | no |
+| enable\_mesh\_feature | Determines whether the module registers the cluster to the fleet. | `bool` | `false` | no |
 | enable\_vpc\_sc | Determines whether to enable VPC-SC for this ASM installation. For more information read https://cloud.google.com/service-mesh/docs/managed/vpc-sc | `bool` | `false` | no |
 | fleet\_id | The fleet to use for this ASM installation. | `string` | `""` | no |
 | multicluster\_mode | [Preview] Determines whether remote secrets should be autogenerated across fleet cluster. | `string` | `"manual"` | no |

modules/asm/hub.tf

@@ -0,0 +1,35 @@
+/**
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+resource "google_gke_hub_membership" "membership" {
+  count         = var.enable_fleet_registration ? 1 : 0
+  provider      = google-beta
+  project       = var.project_id
+  membership_id = "${data.google_container_cluster.asm.name}-membership"
+  endpoint {
+    gke_cluster {
+      resource_link = "//container.googleapis.com/${data.google_container_cluster.asm.id}"
+    }
+  }
+}
+
+resource "google_gke_hub_feature" "mesh" {
+  count    = var.enable_mesh_feature ? 1 : 0
+  name     = "servicemesh"
+  project  = var.project_id
+  location = "global"
+  provider = google-beta
+}

modules/asm/main.tf

@@ -46,6 +46,8 @@ resource "kubernetes_config_map" "asm_options" {
   data = {
     multicluster_mode = var.multicluster_mode
   }
+
+  depends_on = [google_gke_hub_membership.membership, google_gke_hub_feature.mesh]
 }
 
 module "cpr" {

modules/asm/variables.tf

@@ -74,3 +74,15 @@ variable "enable_vpc_sc" {
   type        = bool
   default     = false
 }
+
+variable "enable_fleet_registration" {
+  description = "Determines whether the module enables the mesh feature on the fleet."
+  type        = bool
+  default     = false
+}
+
+variable "enable_mesh_feature" {
+  description = "Determines whether the module registers the cluster to the fleet."
+  type        = bool
+  default     = false
+}