Configure a Virtual Machine Scale Set with an existing Azure Standard Load Balancer

In this article, you'll learn how to configure a Virtual Machine Scale Set with an existing Azure Load Balancer. With an existing virtual network and standard sku load balancer, you can deploy a Virtual Machine Scale Set with a few clicks in the Azure portal, or with a few lines of code in the Azure CLI or Azure PowerShell using the tabs below.

Azure Portal

Prerequisites

• An Azure account with an active subscription. Create an account for free.
• • An Azure Virtual Network for the Virtual Machine Scale Set and the load balancer.
• An existing standard sku load balancer in the subscription where the Virtual Machine Scale Set will be deployed. Ensure the load balancer has a backend pool.

Sign in to the Azure portal

Sign in to the Azure portal.

Deploy Virtual Machine Scale Set with existing load balancer

In this section, you'll create a Virtual Machine Scale Set in the Azure portal with an existing Azure load balancer.

Note

The following steps assume a virtual network named myVNet and an Azure load balancer named myLoadBalancer has been previously deployed.

1. On the top left-hand side of the screen, select Create a resource and search for Virtual Machine Scale Set in the marketplace search.

2. Select Virtual machine scale set and Select Create.

3. In Create a virtual machine scale set, enter, or select this information in the Basics tab:

   Setting	Value
   Project details
   Subscription	Select your Azure subscription
   Resource Group	Select Create new, enter myResourceGroup, then select OK, or select an existing resource group.
   Scale set details
   Virtual Machine Scale Set name	Enter myVMSS
   Region	Select East US 2
   Availability zone	Select None
   Orchestration
   Orchestration mode	Select Uniform
   Security type	Select Standard
   Scaling
   Scaling mode	Select Manual
   Instance count	Enter 2
   Instance details
   Image	Select Ubuntu Server 22.04 LTS
   Azure Spot instance	Select No
   Size	Leave at default
   Administrator account
   Authentication type	Select SSH public key
   Username	Enter a username for the SSH public key.
   SSH public key source	Select Generate new key pair.
   SSH key type	Select RSA SSH Format.
   Key pair name	Enter a name for the key pair.

4. Select the Networking tab or select Next: Spot > Next: Disks > Next: Networking.

5. Enter or select this information in the Networking tab:

   Setting	Value
   Virtual Network Configuration
   Virtual network	Select myVNet or your existing virtual network.
   Load balancing
   Load balancing options	Select Azure load balancer
   Select a load balancer	Select myLoadBalancer or your existing load balancer
   Select a backend pool	Select myBackendPool or your existing backend pool.

6. Select the Management tab.

7. In the Management tab, set Boot diagnostics to Off.

8. Select the blue Review + create button.

9. Review the settings and select the Create button.

Azure CLI

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. Ensure the load balancer has a backend pool.
• 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 Ubuntu2204 \
    --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.

Azure PowerShell

Prerequisites

• An Azure account with an active subscription. Create an account for free.
• • An Azure Virtual Network for the Virtual Machine Scale Set and the load balancer.
• An existing standard sku load balancer in the subscription where the Virtual Machine Scale Set will be deployed. Ensure the load balancer has a backend pool.

Azure Cloud Shell

Azure hosts Azure Cloud Shell, an interactive shell environment that you can use through your browser. You can use either Bash or PowerShell with Cloud Shell to work with Azure services. You can use the Cloud Shell preinstalled commands to run the code in this article, without having to install anything on your local environment.

To start Azure Cloud Shell:

Option	Example/Link
Select Try It in the upper-right corner of a code or command block. Selecting Try It doesn't automatically copy the code or command to Cloud Shell.
Go to https://shell.azure.com, or select the Launch Cloud Shell button to open Cloud Shell in your browser.
Select the Cloud Shell button on the menu bar at the upper right in the Azure portal.

To use Azure Cloud Shell:

1. Start Cloud Shell.

2. Select the Copy button on a code block (or command block) to copy the code or command.

3. Paste the code or command into the Cloud Shell session by selecting Ctrl+Shift+V on Windows and Linux, or by selecting Cmd+Shift+V on macOS.

4. Select Enter to run the code or command.

Note

We recommend that you use the Azure Az PowerShell module to interact with Azure. To get started, see Install Azure PowerShell. To learn how to migrate to the Az PowerShell module, see Migrate Azure PowerShell from AzureRM to Az.

Sign in to Azure CLI

Sign into Azure with Connect-AzAccount

Connect-AzAccount

Deploy a Virtual Machine Scale Set with existing load balancer

Deploy a Virtual Machine Scale Set with New-AzVMss. Replace the values in brackets with the names of the resources in your configuration.

$rsg = <resource-group>
$loc = <location>
$vms = <vm-scale-set-name>
$vnt = <virtual-network>
$sub = <subnet-name>
$lbn = <load-balancer-name>
$pol = <upgrade-policy-mode>
$img = <image-name>
$bep = <backend-pool-name>
$img = <image-name>

$lb = Get-AzLoadBalancer -ResourceGroupName $rsg -Name $lbn

New-AzVmss -ResourceGroupName $rsg -Location $loc -VMScaleSetName $vms -VirtualNetworkName $vnt -SubnetName $sub -LoadBalancerName $lb -UpgradePolicyMode $pol

The below example deploys a Virtual Machine Scale Set with the following values:

• 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

$rsg = "myResourceGroup"
$loc = "East US"
$vms = "myVMSS"
$vnt = "myVNet"
$sub = "default"
$pol = "Automatic"
$lbn = "myLoadBalancer"
$bep = "myBackendPool"
$img = "Ubuntu2204"

$lb = Get-AzLoadBalancer -ResourceGroupName $rsg -Name $lbn

New-AzVmss -ResourceGroupName $rsg -Location $loc -VMScaleSetName $vms -VirtualNetworkName $vnt -SubnetName $sub -LoadBalancerName $lb -UpgradePolicyMode $pol -BackendPoolName $bep -ImageName $img

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?