Azure Virtual Desktop – Scaling Automation

Table of Contents

Introduction

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Requirements

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Services

Permissions

Automation Account

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PowerShell Runbook

Connect to Azure Subscription

This part of the script executes a Sign-In using the Service Principal that was created by adding the Azure RunAsConnection.

				
					## Connect to Azure using Run As Connection
$connectionName = "AzureRunAsConnection"
$connection = Get-AutomationConnection -Name $connectionName
try
{
    $connectionResult = Connect-AzAccount `
    -ServicePrincipal `
    -Tenant $connection.TenantID `
    -ApplicationId $connection.ApplicationID `
    -CertificateThumbprint $connection.CertificateThumbprint
    write-output "Login successful.."
    write-output $connectionResult
}
catch
{
    write-output "Login with $connectionName failed..."
    write-output $connectionResult
}
				

Auto Scaling Tag

This part of the script executes a Sign-In using the Service Principal that was created by adding the Azure RunAsConnection.

				
					## Declare local variables
$AutoScaleTag = "WVDAutoScale"
## Start processing of host pools
write-output "Getting HostPools with AutoScaling enabled..."
$varHostPoolsRscs = Get-AzResource -ResourceType Microsoft.DesktopVirtualization/hostpools | Where-Object {$_.Tags."$AutoScaleTag" -eq $true}
				

Get Azure Virtual Desktop Hostpool

This part of the script executes a Sign-In using the Service Principal that was created by adding the Azure RunAsConnection.

				
					if($varHostPoolsRscs.Count -gt 0)
{
    foreach ($varHostPoolsRsc in $varHostPoolsRscs)
    {
        Write-Output " "
        Write-Output "==============================================================="
        $varWvdCoreRscGroup = $varHostPoolsRsc.ResourceGroupName
        $Hostpool = Get-AzWvdHostPool -Name $varHostPoolsRsc.Name -ResourceGroupName $varWvdCoreRscGroup
        $HostPoolName = $Hostpool.Name 
        Write-Output "Found HostPool to AutoScale. [$HostPoolName] "
        ...
    }
}
				

Evaluate Hostpool Tags

This part of the script executes a Sign-In using the Service Principal that was created by adding the Azure RunAsConnection.

				
					if($varHostPoolsRscs.Count -gt 0)
{
    foreach ($varHostPoolsRsc in $varHostPoolsRscs)
    {
        ...
        Write-Output "Getting AutoScale Config from Hostpool tags..."
        $HostpoolTags = Get-AzResource -ResourceType Microsoft.DesktopVirtualization/hostpools | Where-Object {$_.Name -eq $varHostPoolsRsc.Name} | Select-Object -ExpandProperty Tags
        Write-Output "--------------------------------------------------------------"
        Write-Output "Check if all configuration values are set..."
        if($HostpoolTags."WVDUserBuffer")
        {
            [int32]$buffer = $HostpoolTags."WVDUserBuffer"
            Write-Output "Off-Peak User Buffer set to (Tag): $buffer"
        }
        else
        {
            [int32]$buffer = Get-AutomationVariable -Name 'wvduserbuffer'
            Write-Output "Off-Peak User Buffer set to (Default): $buffer"
        }
        if($HostpoolTags."WVDMinHosts")
        {
            [int32]$minhosts = $HostpoolTags."WVDMinHosts"
            Write-Output "Minimum Session Hosts set to (Tag): $minhosts"
        }
        else
        {
            [int32]$minhosts = Get-AutomationVariable -Name 'wvdminhosts'
            Write-Output "Minimum Session Hosts set to (Default): $minhosts"
        }
        if($HostpoolTags."WVDPeakUserBuffer")
        {
            [int32]$peakbuffer = $HostpoolTags."WVDPeakUserBuffer"
            Write-Output "Peak User Buffer set to (Tag): $peakbuffer"
        }
        else
        {
            [int32]$peakbuffer = Get-AutomationVariable -Name 'wvdpeakuserbuffer'
            Write-Output "Peak User Buffer set to (Default): $peakbuffer"
        }
        if($HostpoolTags."WVDPeakHours")
        {
            [string]$peakhour = $HostpoolTags."WVDPeakHours"
            Write-Output "Peak Hours set to (Tag): $peakhour"
        }
        else
        {
            [string]$peakhour = Get-AutomationVariable -Name 'wvdpeakhour'
            Write-Output "Peak Hours set to (Default): $peakhour"
        } 
        ...
    }
}
				

Get Azure Virtual Desktop Hostpool

This part of the script executes a Sign-In using the Service Principal that was created by adding the Azure RunAsConnection.

				
					if($varHostPoolsRscs.Count -gt 0)
{
    foreach ($varHostPoolsRsc in $varHostPoolsRscs)
    {
        Write-Output " "
        Write-Output "==============================================================="
        $varWvdCoreRscGroup = $varHostPoolsRsc.ResourceGroupName
        $Hostpool = Get-AzWvdHostPool -Name $varHostPoolsRsc.Name -ResourceGroupName $varWvdCoreRscGroup
        $HostPoolName = $Hostpool.Name 
        Write-Output "Found HostPool to AutoScale. [$HostPoolName] "
        ...
    }
}
				

Hostpool Configuration

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Resource Tags

Name	Expected value	Description
WVDAutoScale	True or False	Enables or disables scaling automation for the specific hostpool resource.
Content	Content	Content