Create a Virtual Machine Scale Set

This article guides you through the process of creating a Virtual Machine Scale Set (VMSS) in Azure. VMSS allows you to deploy and manage a set of identical, load-balanced virtual machines. This is crucial for building highly available and scalable applications.

Method 1: Using the Azure Portal

The Azure portal provides a user-friendly graphical interface for creating VMSS. Follow these steps:

1. Sign in to the Azure portal: Navigate to portal.azure.com and sign in with your Azure account.
2. Search for Virtual Machine Scale Sets: In the search bar at the top of the portal, type "Virtual machine scale sets" and select it from the results.
3. Create a new Scale Set: Click the + Create button.

You will be presented with several configuration tabs. Here's a breakdown of the essential ones:

Basics Tab

• Subscription: Select your Azure subscription.
• Resource group: Choose an existing resource group or create a new one.
• Name: Provide a unique name for your VM scale set.
• Region: Select the Azure region where you want to deploy your scale set.
• Availability Zone: Choose an availability zone for enhanced resilience.
• Orchestration mode: Typically, 'Uniform' is used for traditional VMSS.
• Scale (instance count): Set the initial number of VM instances.
• Operating system image: Select the desired OS image (e.g., Windows Server, Ubuntu).
• Size: Choose the VM size that meets your application's requirements.
• Administrator account: Configure username and password or SSH public key.
• Disks: Configure OS disk type and optionally data disks.

Networking Tab

• Virtual network: Select or create a virtual network.
• Subnet: Choose a subnet within the virtual network.
• Load balancing: Configure an Azure Load Balancer or Application Gateway to distribute traffic.

Scaling Tab

• Manual or Automatic: Define how instances are scaled. Automatic scaling uses rules based on metrics like CPU usage.
• Scale-in/out rules: Configure thresholds and actions for automatic scaling.

Management Tab

• Boot diagnostics: Enable to capture boot logs for troubleshooting.
• Identity: Configure managed identity if your VMs need to access other Azure resources securely.

After configuring all tabs, review your settings and click Create.

Method 2: Using Azure CLI

The Azure Command-Line Interface (CLI) is a powerful tool for automating Azure resource management. Here's how to create a VM scale set using CLI:

Prerequisites:

• Install the Azure CLI.
• Sign in to your Azure account:
  az login

Create a Resource Group (if needed):

Create the VM Scale Set:

This example creates a Linux VM scale set with Ubuntu LTS.

For Windows VMSS, use an appropriate image like Win2019Datacenter and manage credentials differently (e.g., --admin-password).

Common VMSS CLI Commands:

• List VMSS in a resource group:
  az vmss list --resource-group myResourceGroup
• Scale a VMSS:
  az vmss scale --resource-group myResourceGroup --name myScaleSet --new-capacity 5
• Delete a VMSS:
  az vmss delete --resource-group myResourceGroup --name myScaleSet

Method 3: Using ARM Templates or Bicep

For infrastructure as code (IaC) approaches, you can use Azure Resource Manager (ARM) templates or Bicep files. These declarative files define your desired Azure infrastructure and allow for repeatable deployments.

An ARM template for VMSS typically involves defining:

• The scale set resource itself.
• Network resources (Virtual Network, Load Balancer, Public IP).
• Identity and extensions.
• Scaling profiles.

You can export existing ARM templates from the Azure portal or find samples in the Azure Quickstart Templates repository.

Next Steps

Once your VM scale set is created, consider the following:

• Configuring applications: Deploy your application code to the VM instances.
• Monitoring: Set up Azure Monitor for performance and health insights.
• Load balancing: Ensure your load balancer is correctly configured to distribute traffic.
• Customization: Explore custom images, extensions, and scaling policies.