Add multiple Virtual Machine Scale Set instances behind one Azure Load Balancer

• Access to the Azure portal
• An Azure account with an active subscription. Create an account for free
• Two or more Virtual Machine Scale Sets
  • Ensure the upgrade policy is set to automatic.
    • If manual upgrade policy is used, upgrade all virtual machine instances after attaching it to the load balancer.
• An existing standard SKU load balancer in the same subscription and virtual network as the Virtual Machine Scale Sets.
  • The load balancer must also have a backend pool with health probes and load balancing rules attached.

• An Azure account with an active subscription. Create an account for free
• Two or more Virtual Machine Scale Sets
  • Ensure that the upgrade policy is set to automatic.
    • If manual upgrade policy is used, upgrade all virtual machine instances after attaching it to the load balancer.
• An existing standard SKU load balancer in the same subscription and virtual network as the Virtual Machine Scale Sets.
  • The load balancer must also have a backend pool with health probes and load balancing rules attached.
• Access to the Azure portal CLI

• Use the Bash environment 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 sign-in 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.

1. Sign in to the Azure portal.
2. In the search box at the top of the portal, enter Load balancer. Select Load balancers in the search results.
3. Select your balancer from the list.
4. In your load balancer's page, select Backend pools under Settings.
5. Select your backend pool.
6. In your backend pool's page, select + Add under IP configurations
7. Select the two Virtual Machine Scale Sets that you want to add to the backend pool.
8. Select Add and Save.

1. Connect to your Azure subscription with Azure CLI.

2. Add the first Virtual Machine Scale Set to a load balancer with az vmss update, and replace the values in brackets with the names of the resources in your configuration.

   
   az vmss update\
       --resource-group <resource-group> \
       --name <vmss-name> \
       --add  virtualMachineProfile.networkProfile.networkInterfaceConfigurations[0].ipConfigurations[0].loadBalancerBackendAddressPools "{'id':'/subscriptions/<SubscriptionID>/resourceGroups/<Resource Group> /providers/Microsoft.Network/loadBalancers/<Load Balancer Name>/backendAddressPools/<Backend address pool name >'}" 
   
   

This example deploys a Virtual Machine Scale Set with the following defined values:

• Virtual Machine Scale Set named myVMSS
• Azure Load Balancer named MyLB
• Load Balancer backend pool named mybackend
• Resource group named myResourceGroup
• Subscription ID named SubscriptionID

az vmss update \ 
    --resource-group myResourceGroup \
    --name myVMSS \
    --add virtualMachineProfile.networkProfile.networkInterfaceConfigurations[0].ipConfigurations[0].loadBalancerBackendAddressPools "{'id':'/subscriptions/SubscriptionID/resourceGroups/myResourceGroup /providers/Microsoft.Network/loadBalancers/MyLb/backendAddressPools/mybackend'}" 

3. Repeat the steps to attach your second Virtual Machine Scale Set to the backend pool of the Azure Load Balancer with az vmss update.