Adding Automatic Zone Placement

[audreyttt]

Description

Adding four new parameters to New-AzVmssConfig and Update-AzVmss, as requested in this design: https://github.com/Azure/azure-powershell-cmdlet-review-pr/issues/1510

Mandatory Checklist

• Please choose the target release of Azure PowerShell. (⚠️Target release is a different concept from API readiness. Please click below links for details.)

  • General release
  • Public preview
  • Private preview
  • Engineering build
  • No need for a release

• Check this box to confirm: I have read the Submitting Changes section of CONTRIBUTING.md and reviewed the following information:

• SHOULD update ChangeLog.md file(s) appropriately
  • Update src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md.
    • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header in the past tense.
  • Should not change ChangeLog.md if no new release is required, such as fixing test case only.
• SHOULD regenerate markdown help files if there is cmdlet API change. Instruction
• SHOULD have proper test coverage for changes in pull request.
• SHOULD NOT adjust version of module manually in pull request

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[Copilot]

Pull request overview

This pull request adds Automatic Zone Placement functionality for Virtual Machine Scale Sets (VMSS) by introducing four new parameters to New-AzVmssConfig, Update-AzVmss, and New-AzVmss cmdlets. The feature enables automatic distribution of VMSS instances across availability zones with configurable constraints, addressing the requirements outlined in the linked design document.

Key changes:

• Added ZonePlacementPolicy parameter to control automatic zone selection (values: "Any" for VMs, "Auto" for VMSS)
• Added MaxZoneCount parameter to limit the maximum number of zones used when policy is "Auto"
• Added EnableMaxInstancePercentPerZone switch and ValueMaxInstancePercentPerZone to control the percentage distribution of VMs per zone
• Implemented validation to ensure Overprovision is false when ZonePlacementPolicy is specified

Reviewed changes

Copilot reviewed 9 out of 14 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
src/Compute/Compute/ChangeLog.md	Added changelog entry documenting the new parameters, but with incorrect casing
src/Compute/Compute/help/New-AzVmss.md	Added documentation for ZonePlacementPolicy parameter in New-AzVmss cmdlet
src/Compute/Compute/help/New-AzVmssConfig.md	Added documentation for all four new parameters in New-AzVmssConfig cmdlet
src/Compute/Compute/help/Update-AzVmss.md	Added documentation for all four new parameters in Update-AzVmss cmdlet
src/Compute/Compute/Generated/VirtualMachineScaleSet/Config/NewAzureRmVmssConfigCommand.cs	Implemented parameter definitions and zone placement logic for config cmdlet, with nested value parameter handling
src/Compute/Compute/Generated/VirtualMachineScaleSet/VirtualMachineScaleSetUpdateMethod.cs	Implemented parameter definitions and zone placement logic for update cmdlet with critical bugs in parameter type and object assignment
src/Compute/Compute/Generated/Models/PSVirtualMachineScaleSet.cs	Added Placement property to the PowerShell model object
src/Compute/Compute/Manual/PSVirtualMachineScaleSet.cs	Added convenience ZonePlacementPolicy string property for simple parameter set
src/Compute/Compute/Manual/VirtualMachineScaleSetCreateOrUpdateMethod.cs	Added ZonePlacementPolicy parameter to New-AzVmss simple parameter set
src/Compute/Compute/Strategies/ComputeRp/VirtualMachineScaleSetStrategy.cs	Updated VMSS creation strategy to include Placement object with ZonePlacementPolicy
src/Compute/Compute.Management.Sdk/Generated/Models/VirtualMachineScaleSetUpdate.cs	Added Placement property to SDK update model
src/Compute/Compute.Test/ScenarioTests/VirtualMachineScaleSetTests.ps1	Added comprehensive test covering creation and update scenarios with zone placement parameters
src/Compute/Compute.Test/ScenarioTests/VirtualMachineScaleSetTests.cs	Added test entry point for new zone placement test

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