Configure a Virtual Machine Scale Set with an existing Azure Load Balancer using the Azure CLI

In this article, you'll learn how to configure a Virtual Machine Scale Set with an existing Azure Load Balancer.

Prerequisites

• An Azure account with an active subscription. Create an account for free.

• You need an existing standard sku load balancer in the subscription where the Virtual Machine Scale Set will be deployed.

• You need an Azure Virtual Network for the Virtual Machine Scale Set.

• Use the Bash environment in Azure Cloud Shell. For more information, see Quickstart for Bash in Azure Cloud Shell.

  

• If you prefer to run CLI reference commands locally, install the Azure CLI. If you're running on Windows or macOS, consider running Azure CLI in a Docker container. For more information, see How to run the Azure CLI in a Docker container.

  • If you're using a local installation, sign in to the Azure CLI by using the az login command. To finish the authentication process, follow the steps displayed in your terminal. For other sign-in options, see Sign in with the Azure CLI.

  • When you're prompted, install the Azure CLI extension on first use. For more information about extensions, see Use extensions with the Azure CLI.

  • Run az version to find the version and dependent libraries that are installed. To upgrade to the latest version, run az upgrade.

• This article requires version 2.0.28 or later of the Azure CLI. If using Azure Cloud Shell, the latest version is already installed.

Deploy a Virtual Machine Scale Set with existing load balancer

Deploy a Virtual Machine Scale Set with az vmss create. Replace the values in brackets with the names of the resources in your configuration.

az vmss create \
    --resource-group <resource-group> \
    --name <vmss-name>\
    --image <your-image> \
    --admin-username <admin-username> \
    --generate-ssh-keys  \
    --upgrade-policy-mode Automatic \
    --instance-count 3 \
    --vnet-name <virtual-network-name> \
    --subnet <subnet-name> \
    --lb <load-balancer-name> \
    --backend-pool-name <backend-pool-name>

The below example deploys a Virtual Machine Scale Set with:

• Virtual Machine Scale Set named myVMSS
• Azure Load Balancer named myLoadBalancer
• Load balancer backend pool named myBackendPool
• Azure Virtual Network named myVnet
• Subnet named mySubnet
• Resource group named myResourceGroup
• Ubuntu Server image for the Virtual Machine Scale Set

az vmss create \
    --resource-group myResourceGroup \
    --name myVMSS \
    --image Canonical:UbuntuServer:18.04-LTS:latest \
    --admin-username adminuser \
    --generate-ssh-keys \
    --upgrade-policy-mode Automatic \
    --instance-count 3 \
    --vnet-name myVnet\
    --subnet mySubnet \
    --lb myLoadBalancer \
    --backend-pool-name myBackendPool

Note

After the scale set has been created, the backend port cannot be modified for a load balancing rule used by a health probe of the load balancer. To change the port, you can remove the health probe by updating the Azure virtual machine scale set, update the port and then configure the health probe again.

Next steps

In this article, you deployed a Virtual Machine Scale Set with an existing Azure Load Balancer. To learn more about Virtual Machine Scale Sets and load balancer, see:

• What is Azure Load Balancer?
• What are Virtual Machine Scale Sets?