add readme

Author: bharathkkb

modules/asm/README.md

@@ -0,0 +1,52 @@
+# Terraform Kubernetes Engine ASM Submodule
+
+This module installs [Anthos Service Mesh](https://cloud.google.com/service-mesh/docs) (ASM) in a Kubernetes cluster.
+
+Specifically, this module automates the following steps for [installing ASM](https://cloud.google.com/service-mesh/docs/install):
+
+1. Installing the ASM Istio Operator on your cluster.
+2. Optionally registering your cluster with GKE Hub.
+
+## Usage
+
+There is a [full example](../../examples/simple_regional_with_asm) provided. Simple usage is as follows:
+
+```tf
+module "asm" {
+  source           = "terraform-google-modules/kubernetes-engine/google//modules/asm"
+
+  project_id       = "my-project-id"
+  cluster_name     = "my-cluster-name"
+  location         = module.gke.location
+  cluster_endpoint = module.gke.endpoint
+}
+```
+
+To deploy this config:
+1. Run `terraform apply`
+
+## Requirements
+
+- Anthos Service Mesh [requires](https://cloud.google.com/service-mesh/docs/gke-install-existing-cluster#requirements) an active Anthos license.
+- GKE cluster must have minimum four nodes.
+- Minimum machine type is `e2-standard-4`.
+- GKE cluster must be enrolled in a release channel. ASM does not support static version.
+- ASM on a private GKE cluster requires adding a firewall rule to open port 15017 if you want to use [automatic sidecar injection](https://cloud.google.com/service-mesh/docs/proxy-injection).
+- Only one ASM per Google Cloud project is supported.
+
+
+ <!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
+## Inputs
+
+| Name | Description | Type | Default | Required |
+|------|-------------|:----:|:-----:|:-----:|
+| cluster\_endpoint | The GKE cluster endpoint. | string | n/a | yes |
+| cluster\_name | The unique name to identify the cluster in ASM. | string | n/a | yes |
+| enable\_gke\_hub\_registration | Enables GKE Hub Registration when set to true | bool | `"true"` | no |
+| gke\_hub\_membership\_name | Memebership name that uniquely represents the cluster being registered on the Hub | string | `"gke-asm-membership"` | no |
+| gke\_hub\_sa\_name | Name for the GKE Hub SA stored as a secret `creds-gcp` in the `gke-connect` namespace. | string | `"gke-hub-sa"` | no |
+| location | The location (zone or region) this cluster has been created in. | string | n/a | yes |
+| project\_id | The project in which the resource belongs. | string | n/a | yes |
+| skip\_gcloud\_download | Whether to skip downloading gcloud (assumes gcloud and kubectl already available outside the module) | bool | `"true"` | no |
+
+ <!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->