Lab: Create a custom Windows 10 image from VM1 and deploy new VMs from it (Azure portal)

Lab goal

Build a reusable image from a generalized Windows 10 VM (VM1) using Azure Compute Gallery, then deploy a new VM from that image.

Estimated time

30–60 minutes (depends on image version creation time)

Prerequisites

• Azure subscription with Contributor (or Owner) on the target resource group
• Existing VM named VM1 running Windows 10 Enterprise
• VM1 is already generalized (Sysprep) and stopped (ideally Deallocated)
• You know whether VM1 is Gen1 or Gen2 (you can check in VM properties)

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Part 0: Verify VM1 is ready (generalized + deallocated)

Step 0.1: Confirm VM is stopped (and deallocated)

1. Azure portal > Virtual machines
2. Open VM1
3. On the Overview page, check Status
   • Target: Stopped (deallocated)

If it’s only “Stopped”, click Stop from the VM blade (this deallocates it).

Step 0.2: Confirm generalization (sanity check)

If you already ran Sysprep, proceed. If not, the imaging step may fail or produce a non-reusable image.

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Part 1: Create the Azure Compute Gallery

Step 1.1: Create the gallery

1. Azure portal search: Azure Compute Gallery
2. Select Create
3. Fill in:
   • Subscription: your subscription
   • Resource group: use the same RG as VM1 or a dedicated “Images-RG”
   • Name: acg-pool1-images (example)
   • Region: same region as VM1 (recommended)
4. Select Review + create > Create

✅ Output: A gallery exists to store definitions and versions.

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Part 2: Create an Image Definition

Step 2.1: Create definition

1. Open the gallery you created
2. Left menu: Image definitions > Create
3. Configure:
   • Region: same as gallery
   • Name: win10-ent-custom
   • Operating system: Windows
   • OS state: Generalized
   • Publisher: Contoso (any label)
   • Offer: Win10Custom
   • SKU: avd
   • VM generation: match VM1 (Gen1 or Gen2)
4. Select Review + create > Create

✅ Output: Image definition created (think “image family”).

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Part 3: Create an Image Version (from VM1)

Step 3.1: Start version creation

1. Open the image definition (win10-ent-custom)
2. Left menu: Versions > Create

Step 3.2: Basics

Fill:

• Version number: 1.0.0
• Source: choose Virtual machine
• Source VM: select VM1
• End of life date: optional (skip unless you use governance)

Step 3.3: Replication (keep it simple for the lab)

• Replica count: 1
• Target regions: same region only (for lab)
• Leave advanced options default unless you have a reason.

Step 3.4: Create

Select Review + create > Create

⏳ Wait for deployment to finish.

✅ Output: A deployable image version exists in the gallery.

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Part 4: Deploy a new VM from the Image Version

Step 4.1: Create VM from image version

1. Open the new image version (1.0.0)
2. Select Create VM

Step 4.2: Basics

• Resource group: same as host pool RG or lab RG
• VM name: VM1-Clone-01
• Region: same region as the image
• Availability options: default for lab
• Image: should already show your gallery image version
• Size: pick a test size (example: Standard_D2s_v5)
• Administrator account: set username/password (or use Azure AD login later if configured)

Step 4.3: Disks

• Keep defaults for lab
• OS disk type: Standard SSD is fine

Step 4.4: Networking

• Choose your existing VNet/Subnet
• Public IP: optional (for lab it’s convenient)
• NIC NSG: basic inbound (RDP only if needed)

Step 4.5: Management

• Boot diagnostics: On (recommended)
• Monitoring: optional

Step 4.6: Review + create

Select Create

✅ Output: A new VM deployed from your custom image.

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Part 5: Validation (prove it’s your custom image)

Step 5.1: Connect and validate customizations

1. Open VM1-Clone-01
2. Connect using RDP (if enabled) or your preferred method
3. Validate:
   • Installed apps you added on VM1 exist
   • Custom settings/branding changes exist
   • Windows version/build matches expectation

Step 5.2: Quick Azure-side validation

• Gallery > Image definition > Versions:
  • Confirm 1.0.0 exists and is Succeeded
• VM > Extensions + applications:
  • Confirm only expected extensions exist (if any)

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Part 6: Cleanup (optional)

To avoid costs:

• Delete VM1-Clone-01 (and associated resources)
• Keep the gallery/definition/version if you want to reuse it later

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Troubleshooting quick hits

Image version creation fails

Common causes:

• VM not generalized (Sysprep not done)
• VM not stopped/deallocated
• VM generation mismatch in image definition

Can’t find VM1 as a source

• VM1 must be in the same subscription you’re working in
• Ensure you have permissions on the VM resource group
• VM must be in a valid state (stopped)

Deployed VM doesn’t look like VM1

• You may have created the image before finishing customization
• Confirm you deployed from the gallery image version, not a marketplace image

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Lab extension (recommended next)

If your goal is Azure Virtual Desktop scale:

• Use the gallery image version to build new session hosts via:
  • AVD host pool “Add session hosts” workflow
  • ARM/Bicep deployment for host scaling
  • Image versioning strategy (1.0.1, 1.1.0) for patch cadence and rollback