How to Create VM Scale Set in Azure: Step-by-Step Guide

To create a VM Scale Set in Azure, use the az vmss create command with parameters like resource group, name, image, and instance count. This command sets up multiple identical virtual machines managed as a group for easy scaling and management.

Syntax

The basic syntax to create a VM Scale Set in Azure using Azure CLI is:

• az vmss create: Command to create the scale set.
• --resource-group: The name of the resource group where the scale set will be created.
• --name: The name you want to give your VM Scale Set.
• --image: The OS image for the VMs, e.g., UbuntuLTS.
• --instance-count: Number of VM instances in the scale set.
• --admin-username and --admin-password: Credentials for VM access.

bash

az vmss create --resource-group MyResourceGroup --name MyScaleSet --image UbuntuLTS --instance-count 3 --admin-username azureuser --admin-password MyP@ssword123

Example

This example creates a VM Scale Set named MyScaleSet in the resource group MyResourceGroup with 3 Ubuntu virtual machines. It sets the admin username and password for access.

bash

az group create --name MyResourceGroup --location eastus
az vmss create --resource-group MyResourceGroup --name MyScaleSet --image UbuntuLTS --instance-count 3 --admin-username azureuser --admin-password MyP@ssword123

Output

{
  "id": "/subscriptions/xxxx/resourceGroups/MyResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/MyScaleSet",
  "location": "eastus",
  "name": "MyScaleSet",
  "properties": {
    "provisioningState": "Succeeded",
    "virtualMachineProfile": {
      "storageProfile": {
        "imageReference": {
          "offer": "UbuntuServer",
          "publisher": "Canonical",
          "sku": "18.04-LTS",
          "version": "latest"
        }
      }
    },
    "overprovision": true
  },
  "sku": {
    "capacity": 3,
    "name": "Standard_DS1_v2",
    "tier": "Standard"
  },
  "type": "Microsoft.Compute/virtualMachineScaleSets"
}

Common Pitfalls

• Using weak passwords or missing admin credentials causes creation failure.
• Not specifying a resource group or using a non-existent one will cause errors.
• Choosing an unsupported image name or region mismatch can prevent deployment.
• Forgetting to open required ports (like SSH port 22) can block access to VMs.

bash

az vmss create --resource-group MyResourceGroup --name MyScaleSet --image UbuntuLTS --instance-count 3 --admin-username azureuser

# This will fail because admin password is missing.

# Correct way:
az vmss create --resource-group MyResourceGroup --name MyScaleSet --image UbuntuLTS --instance-count 3 --admin-username azureuser --admin-password MyP@ssword123

Quick Reference

Remember these key points when creating a VM Scale Set:

• Always create or specify an existing resource group first.
• Use a strong admin password or SSH key for security.
• Choose the right VM image and size for your workload.
• Set the instance count based on expected load and budget.
• Open necessary network ports for VM access.

Key Takeaways

Use the az vmss create command with required parameters to create a VM Scale Set.

Always specify a valid resource group and strong admin credentials.

Choose the correct VM image and instance count for your needs.

Open necessary network ports to access your VMs after creation.

Check for errors related to missing parameters or unsupported images.