Configure autoscale with PowerShell

Autoscale ensures that you have the right amount of resources running to handle the fluctuating load of your application. You can configure autoscale using the Azure portal, Azure CLI, PowerShell or ARM or Bicep templates.

This article shows you how to configure autoscale for a Virtual Machine Scale Set with PowerShell. The configurations use the following steps:

• Create a scale set that you can autoscale
• Create rules to scale in and scale out
• Create a profile that uses your rules
• Apply the autoscale settings
• Update your autoscale settings with notifications

Prerequisites

To configure autoscale using PowerShell, you need an Azure account with an active subscription. You can create an account for free.

Set up your environment

#Set the subscription Id, VMSS name, and resource group name
$subscriptionId = (Get-AzContext).Subscription.Id
$resourceGroupName="rg-powershell-autoscale"
$vmssName="vmss-001"

Create a Virtual Machine Scale Set

Create a scale set using the following cmdlets. Set the $resourceGroupName and $vmssName variables to suite your environment.

# create a new resource group
New-AzResourceGroup -ResourceGroupName $resourceGroupName -Location "EastUS"

# Create login credentials for the VMSS
$Cred = Get-Credential
$vmCred = New-Object System.Management.Automation.PSCredential($Cred.UserName, $Cred.Password)


New-AzVmss `
 -ResourceGroupName $resourceGroupName `
 -Location "EastUS" `
 -VMScaleSetName $vmssName `
 -Credential $vmCred `
 -VirtualNetworkName "myVnet" `
 -SubnetName "mySubnet" `
 -PublicIpAddressName "myPublicIPAddress" `
 -LoadBalancerName "myLoadBalancer" `
 -OrchestrationMode "Flexible"

Create autoscale settings

To create autoscale setting using PowerShell, follow the sequence below:

1. Create rules using New-AzAutoscaleScaleRuleObject
2. Create a profile using New-AzAutoscaleProfileObject
3. Create the autoscale settings using New-AzAutoscaleSetting
4. Update the settings using Update-AzAutoscaleSetting

Create rules

Create scale in and scale out rules then associated them with a profile. Rules are created using the New-AzAutoscaleScaleRuleObject.

The following PowerShell script creates two rules.

• Scale out when Percentage CPU exceeds 70%
• Scale in when Percentage CPU is less than 30%

$rule1=New-AzAutoscaleScaleRuleObject `
    -MetricTriggerMetricName "Percentage CPU" `
    -MetricTriggerMetricResourceUri "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName"  `
    -MetricTriggerTimeGrain ([System.TimeSpan]::New(0,1,0)) `
    -MetricTriggerStatistic "Average" `
    -MetricTriggerTimeWindow ([System.TimeSpan]::New(0,5,0)) `
    -MetricTriggerTimeAggregation "Average" `
    -MetricTriggerOperator "GreaterThan" `
    -MetricTriggerThreshold 70 `
    -MetricTriggerDividePerInstance $false `
    -ScaleActionDirection "Increase" `
    -ScaleActionType "ChangeCount" `
    -ScaleActionValue 1 `
    -ScaleActionCooldown ([System.TimeSpan]::New(0,5,0))


$rule2=New-AzAutoscaleScaleRuleObject `
    -MetricTriggerMetricName "Percentage CPU" `
    -MetricTriggerMetricResourceUri "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName"  `
    -MetricTriggerTimeGrain ([System.TimeSpan]::New(0,1,0)) `
    -MetricTriggerStatistic "Average" `
    -MetricTriggerTimeWindow ([System.TimeSpan]::New(0,5,0)) `
    -MetricTriggerTimeAggregation "Average" `
    -MetricTriggerOperator "LessThan" `
    -MetricTriggerThreshold 30 `
    -MetricTriggerDividePerInstance $false `
    -ScaleActionDirection "Decrease" `
    -ScaleActionType "ChangeCount" `
    -ScaleActionValue 1 `
    -ScaleActionCooldown ([System.TimeSpan]::New(0,5,0))

The table below describes the parameters used in the New-AzAutoscaleScaleRuleObject cmdlet.

Create a default autoscale profile and associate the rules

After defining the scale rules, create a profile. The profile specifies the default, upper, and lower instance count limits, and the times that the associated rules can be applied. Use the New-AzAutoscaleProfileObject cmdlet to create a new autoscale profile. As this is a default profile, it doesn't have any schedule parameters. The default profile is active at times that no other profiles are active

$defaultProfile=New-AzAutoscaleProfileObject `
    -Name "default" `
    -CapacityDefault 1 `
    -CapacityMaximum 10 `
    -CapacityMinimum 1 `
    -Rule $rule1, $rule2

The table below describes the parameters used in the New-AzAutoscaleProfileObject cmdlet.

Apply the autoscale settings

After fining the rules and profile, apply the autoscale settings using New-AzAutoscaleSetting. To update existing autoscale setting use Update-AzAutoscaleSetting

New-AzAutoscaleSetting `
    -Name vmss-autoscalesetting1 `
    -ResourceGroupName $resourceGroupName `
    -Location eastus `
    -Profile $defaultProfile `
    -Enabled `
    -PropertiesName "vmss-autoscalesetting1" `
    -TargetResourceUri "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName"

Add notifications to your autoscale settings

Add notifications to your sale setting to trigger a webhook or send email notifications when a scale event occurs. For more information on webhook notifications, see New-AzAutoscaleWebhookNotificationObject

Set a webhook using the following cmdlet;

  $webhook1=New-AzAutoscaleWebhookNotificationObject -Property @{} -ServiceUri "http://contoso.com/webhook1"

Configure the notification using the webhook and set up email notification using the New-AzAutoscaleNotificationObject cmdlet:

    $notification1=New-AzAutoscaleNotificationObject `
    -EmailCustomEmail "jason@contoso.com" `
    -EmailSendToSubscriptionAdministrator $true `
    -EmailSendToSubscriptionCoAdministrator $true `
    -Webhook $webhook1

Update your autoscale settings to apply the notification

Update-AzAutoscaleSetting  `
    -Name vmss-autoscalesetting1 `
    -ResourceGroupName $resourceGroupName `
    -Profile $defaultProfile `
    -Notification $notification1 `
    -TargetResourceUri "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName"  

Review your autoscale settings

To review your autoscale settings, load the settings into a variable using Get-AzAutoscaleSetting then output the variable as follows:

    $autoscaleSetting=Get-AzAutoscaleSetting  -ResourceGroupName $resourceGroupName -Name vmss-autoscalesetting1 
    $autoscaleSetting | Select-Object -Property *

Get your autoscale history using AzAutoscaleHistory

Get-AzAutoscaleHistory -ResourceId  /subscriptions/<subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName

Scheduled and recurring profiles

Add a scheduled profile for a special event

Set up autoscale profiles to scale differently for specific events. For example, for a day when demand will be higher than usual, create a profile with increased maximum and minimum instance limits.

The following example uses the same rules as the default profile defined above, but sets new instance limits for a specific date. You can also configure different rules to be used with the new profile.

$highDemandDay=New-AzAutoscaleProfileObject `
    -Name "High-demand-day" `
    -CapacityDefault 7 `
    -CapacityMaximum 30 `
    -CapacityMinimum 5 `
    -FixedDateEnd ([System.DateTime]::Parse("2023-12-31T14:00:00Z")) `
    -FixedDateStart ([System.DateTime]::Parse("2023-12-31T13:00:00Z")) `
    -FixedDateTimeZone "UTC" `
    -Rule $rule1, $rule2

Update-AzAutoscaleSetting  `
    -Name vmss-autoscalesetting1 `
    -ResourceGroupName $resourceGroupName `
    -Profile $defaultProfile, $highDemandDay `
    -Notification $notification1 `
    -TargetResourceUri "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName"  

Add a recurring scheduled profile

Recurring profiles let you schedule a scaling profile that repeats each week. For example, scale to a single instance on the weekend from Friday night to Monday morning.

While scheduled profiles have a start and end date, recurring profiles don't have an end time. A profile remains active until the next profile's start time. Therefore, when you create a recurring profile you must create a recurring default profile that starts when you want the previous recurring profile to finish.

For example, to configure a weekend profile that starts on Friday nights and ends on Monday mornings, create a profile that starts on Friday night, then create recurring profile with your default settings that starts on Monday morning.

The following script creates a weekend profile and an addition default profile to end the weekend profile.

$fridayProfile=New-AzAutoscaleProfileObject `
    -Name "Weekend" `
    -CapacityDefault 1 `
    -CapacityMaximum 1 `
    -CapacityMinimum 1 `
    -RecurrenceFrequency week  `
    -ScheduleDay "Friday" `
    -ScheduleHour 22  `
    -ScheduleMinute 00  `
    -ScheduleTimeZone  "Pacific Standard Time" `
    -Rule $rule1, $rule2


$defaultRecurringProfile=New-AzAutoscaleProfileObject `
    -Name "default recurring profile" `
    -CapacityDefault 2 `
    -CapacityMaximum 10 `
    -CapacityMinimum 2 `
    -RecurrenceFrequency week  `
    -ScheduleDay "Monday" `
    -ScheduleHour 00  `
    -ScheduleMinute 00  `
    -ScheduleTimeZone  "Pacific Standard Time" `
    -Rule $rule1, $rule2

New-AzAutoscaleSetting  `
    -Location eastus `
    -Name vmss-autoscalesetting1 `
    -ResourceGroupName $resourceGroupName `
    -Profile $defaultRecurringProfile, $fridayProfile `
    -Notification $notification1 `
    -TargetResourceUri "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Compute/virtualMachineScaleSets/$vmssName"  

For more information on scheduled profiles, see Autoscale with multiple profiles

Other autoscale commands

For a complete list of PowerShell cmdlets for autoscale, see the PowerShell Module Browser

Clean up resources

To clean up the resources you created in this tutorial, delete the resource group that you created. The following cmdlet deletes the resource group and all of its resources.

Remove-AzResourceGroup -Name $resourceGroupName