How to Use Custom Image for VM in Azure: Step-by-Step Guide

To use a custom image for a VM in Azure, first create the image from a generalized VM or managed disk, then specify this image when creating a new VM using the --image parameter in Azure CLI. This lets you deploy VMs with your own pre-configured OS and software.

Syntax

Use the Azure CLI command to create a VM from a custom image. The key parts are:

• az vm create: Command to create a VM.
• --resource-group: Your Azure resource group name.
• --name: Name for the new VM.
• --image: The custom image resource ID or name.
• --admin-username and --admin-password: Credentials for the VM.

bash

az vm create --resource-group MyResourceGroup --name MyVM --image MyCustomImage --admin-username azureuser --admin-password MyP@ssw0rd!

Example

This example shows how to create a custom image from an existing VM and then deploy a new VM using that image.

bash

# Step 1: Deallocate and generalize the source VM
az vm deallocate --resource-group MyResourceGroup --name SourceVM
az vm generalize --resource-group MyResourceGroup --name SourceVM

# Step 2: Create a custom image from the generalized VM
az image create --resource-group MyResourceGroup --name MyCustomImage --source SourceVM

# Step 3: Create a new VM using the custom image
az vm create --resource-group MyResourceGroup --name NewVM --image MyCustomImage --admin-username azureuser --admin-password MyP@ssw0rd!

Output

Virtual machine 'NewVM' created successfully.

Common Pitfalls

• Not generalizing the source VM: You must run az vm generalize after deallocating the VM to prepare it for imaging.
• Using incorrect image name or ID: Ensure the --image parameter matches the exact name or resource ID of your custom image.
• Missing permissions: Your Azure account must have rights to create images and VMs in the resource group.
• Incorrect admin credentials: Passwords must meet Azure's complexity requirements.

bash

Wrong:
az vm create --resource-group MyResourceGroup --name NewVM --image SourceVM --admin-username azureuser --admin-password MyP@ssw0rd!

Right:
az vm create --resource-group MyResourceGroup --name NewVM --image MyCustomImage --admin-username azureuser --admin-password MyP@ssw0rd!

Quick Reference

Command	Purpose
az vm deallocate	Stop and deallocate the VM before generalizing
az vm generalize	Prepare the VM for image creation
az image create	Create a custom image from a VM or disk
az vm create --image	Create a new VM from a custom image

Key Takeaways

Always deallocate and generalize the source VM before creating a custom image.

Use the custom image name or resource ID with the --image parameter when creating a VM.

Ensure your admin credentials meet Azure's security requirements.

Verify you have proper permissions to create images and VMs in your resource group.

Use Azure CLI commands in the correct order to avoid deployment errors.