adding howto on az aro extension

Author: Kevin Lamenzo

articles/openshift/howto-using-aro.md

@@ -0,0 +1,160 @@
+---
+title: Using `az aro` | Microsoft Docs
+description: Create, access, and delete clusters with `az aro` extension
+author: klamenzo 
+ms.author: b-lejaku
+ms.service: container-service
+ms.topic: conceptual
+ms.date: 03/02/2020
+keywords: aro, openshift, az aro, red hat, cli
+#Customer intent: As a customer, I want to create an ARO custer using the command line.
+---
+
+# Using `az aro`
+
+The `az aro` extension allows you to create, access, and delete Azure Red Hat OpenShift clusters directly from the command line using the Azure CLI.
+
+> [!Note] 
+> The `az aro` extension is currenty in preview. It may be changed or removed in a future release.
+> To opt-in for the `az aro` extension preview you need to register the `Microsoft.RedHatOpenShift` resource provider.
+> 
+>    ```
+>    az provider register -n Microsoft.RedHatOpenShift --wait
+>    ```
+
+
+## Installing the extension
+
+1. Install the [`az`](https://docs.microsoft.com/en-us/cli/azure/install-azure-cli) client, if you have not already. You will need `az` version 2.0.72 or greater, as this version includes the `az network vnet subnet update --disable-private-link-service-network-policies` flag.
+
+2. Log in to Azure.
+
+   ```
+   az login
+   ```
+
+3. Run the following command to install the `az aro` extension:
+
+   ```
+   az extension add --source https://arosvc.blob.core.windows.net/az-preview/aro-0.1.0-py2.py3-none-any.whl
+   ```
+
+4. Verify the ARO extension is registered.
+
+   ```
+   az -v
+   ...
+   Extensions:
+   aro                                0.1.0
+   ...
+   ```
+
+
+## Prerequisites to create an Azure Red Hat OpenShift v4 cluster
+
+You need the following items to create an Azure Red Hat OpenShift v4 cluster.
+
+* A cluster AAD application (client ID and secret) and service principal, or sufficient AAD permissions for `az aro` to create these for you automatically.
+* The resource provider service principal and cluster service principal must each have the Contributor role on the cluster VNet. If you have the User Access Administrator role on the VNet, `az aro create` will set up the role assignments for you automatically.
+* A VNet containing two empty subnets, each with no network security group attached. Your cluster will be deployed into these subnets. Follow the steps below to create your VNet.
+
+### Create a VNet containing two empty subnets
+
+Follow these steps to create a VNet containing two empty subnets.
+
+1. Set the following variables.
+
+   ```
+   LOCATION=eastus		#the location of your cluster
+   RESOURCEGROUP="v4-$LOCATION"	#the name of the resource group where you want to create your cluster
+   CLUSTER=cluster		#the name of your cluster
+   ```
+
+2. Create a resource group for your cluster.
+
+   ```
+   az group create -g "$RESOURCEGROUP" -l $LOCATION
+   ```
+
+3. Create the VNet.
+
+   ```
+   az network vnet create \
+     -g "$RESOURCEGROUP" \
+     -n vnet \
+     --address-prefixes 10.0.0.0/9 \
+     >/dev/null
+   ```
+
+4. Add two empty subnets to your VNet.
+
+   ```
+    for subnet in "$CLUSTER-master" "$CLUSTER-worker"; do
+     az network vnet subnet create \
+       -g "$RESOURCEGROUP" \
+       --vnet-name vnet \
+       -n "$subnet" \
+       --address-prefixes 10.$((RANDOM & 127)).$((RANDOM & 255)).0/24 \
+       --service-endpoints Microsoft.ContainerRegistry \
+       >/dev/null
+   done
+   ```
+
+5. Disable network policies for private link service on your VNet and subnets. This is a requirement for the ARO service to access and manage the cluster.
+
+   ```
+   az network vnet subnet update \
+     -g "$RESOURCEGROUP" \
+     --vnet-name vnet \
+     -n "$CLUSTER-master" \
+     --disable-private-link-service-network-policies true \
+     >/dev/null
+   ```
+
+
+## Using the extension
+
+After installing the `az aro` extension you can use it to create, access, and delete clusters.
+ 
+### Create a cluster
+
+Run the following command to create a cluster.
+
+```
+az aro create \
+  -g "$RESOURCEGROUP" \
+  -n "$CLUSTER" \
+  --vnet vnet \
+  --master-subnet "$CLUSTER-master" \
+  --worker-subnet "$CLUSTER-worker"
+```
+
+>[!NOTE]
+> It normally takes about 35 minutes to create a cluster.
+
+### Access the cluster console
+
+You can find the cluster console URL (of the form `https://console-openshift-console.apps.<random>.<location>.aroapp.io/`) in the Azure Red Hat OpenShift v4 cluster resource. Run the following command to view the resource:
+
+```
+az aro list -o table
+```
+   
+You can log into the cluster using the `kubeadmin` user.  Run the following command to find the password for the `kubeadmin` user:
+
+```
+az aro list-credentials -g "$RESOURCEGROUP" -n "$CLUSTER"
+```
+
+### Delete a cluster
+
+Run the following command to delete a cluster:
+
+```
+az aro delete -g "$RESOURCEGROUP" -n "$CLUSTER"
+
+# (optional)
+for subnet in "$CLUSTER-master" "$CLUSTER-worker"; do
+  az network vnet subnet delete -g "$RESOURCEGROUP" --vnet-name vnet -n "$subnet"
+done
+```