Creating a Virtual Machine Scale Set (VMSS) in Azure allows you to manage and automatically scale a group of virtual machines.

Here's a step-by-step guide to create a VMSS using the Azure portal:

Step 1: Sign in to Azure Portal

Open your web browser and go to the Azure portal.
Sign in with your Azure account credentials.

Step 2: Navigate to Virtual Machine Scale Sets

In the Azure portal, click on the "Create a resourc" button (+) in the left-hand menu.
In the "Search the Marketplace" box, type "Virtual Machine Scale Sets" and select it from the list.
Click "Create" to start the creation process.
Step 3: Configure Basic Settings
Subscription: Select your Azure subscription.
Resource Group: Select an existing resource group or create a new one.
Name: Enter a name for your scale set.
Region: Choose the region where you want to deploy the VMSS.
Availability Zone: (Optional) Select an availability zone if required.
Orchestration mode: Choose Uniform (recommended for most scenarios) or Flexible.
Step 4: Configure Instance Details
Image: Select an operating system image for your VMs (e.g., Ubuntu Server 20.04 LTS).
Size: Choose a VM size (e.g., Standard DS1 v2).
Step 5: Configure Scaling Settings
Instance Count: Set the initial number of instances (e.g., 2).
Scaling Policy: Configure the scaling policy to automatically increase or decrease the number of instances based on CPU usage, memory, or custom metrics.
Step 6: Configure Networking
Virtual Network: Select an existing virtual network or create a new one.
Subnet: Select a subnet within the chosen virtual network.
Public IP Address: Choose whether to associate a public IP address with the VMs.
Load Balancer: (Optional) Select a load balancer to distribute traffic across the VMs.
Step 7: Configure Management Settings
Diagnostics: Enable boot diagnostics and choose a storage account for storing diagnostic logs.
Identity: (Optional) Assign a managed identity for your VMSS to access other Azure resources securely.
Auto-shutdown: Configure auto-shutdown settings if needed.
Step 8: Review and Create
Review all the settings you have configured.
Click "Review + create" to validate the configuration.
Once validation passes, click "Create" to deploy the VMSS.
Step 9: Monitor and Manage the VMSS
After deployment, navigate to the "Virtual Machine Scale Sets" service in the Azure portal.
Select your newly created VMSS to view its details.
Use the "Instances" tab to monitor the status of individual VM instances.
Use the "Scaling" tab to adjust scaling policies and settings.
Step 10: Connect to a VM Instance
In the VMSS overview, click on "Instances".
Select an instance and click "Connect".
Follow the instructions to connect to the VM instance using SSH (for Linux) or RDP (for Windows).
Conclusion
By following these steps, you can create a Virtual Machine Scale Set in Azure, which allows you to automatically scale your application based on demand, ensuring high availability and performance.