Restart-AppServiceInstances.ps1

Restart-AppServiceInstances.ps1

Param(
    [Parameter(Mandatory=$true)]
    # ID for the Azure subscription containing the App Service
    [string]$SubscriptionId,
    [Parameter(Mandatory=$true)]
    # Name of the App Service on which the restart should be performed
    [string]$AppServiceName,
    [Parameter(Mandatory=$false)]
    # Seconds between each instance restart, defaults to 30
    [int]$SecondsBetweenRestarts = 30
)

$VerbosePreference = "Continue"

$AutomationConnection = Get-AutomationConnection -Name "AzureRunAsConnection"
$ConnectionSplat = @{
    ServicePrincipal = $true 
    Tenant = $AutomationConnection.TenantID
    ApplicationId = $AutomationConnection.ApplicationID
    CertificateThumbprint = $AutomationConnection.CertificateThumbprint
}
Connect-AzAccount @ConnectionSplat

Set-AzContext -Subscription $SubscriptionId | Out-Null

$WebApp = Get-AzWebApp -Name $AppServiceName
$ResourceGroup = $WebApp.ResourceGroup

# This gives you a list of instances for your App Service
$InstancesSplat = @{
    ResourceGroupName = $ResourceGroup
    ResourceType = "Microsoft.Web/sites/instances"
    ResourceName = $AppServiceName
    ApiVersion = "2018-11-01"
}
$ApplicationInstances = Get-AzResource @InstancesSplat

$InstanceCounter = 0
$FailedRestarts = $false
foreach ($Instance in $ApplicationInstances) {
    $InstanceCounter++
    Write-Verbose -Message "Now on instance $InstanceCounter/$($ApplicationInstances.Count)"

    # This gives you list of processes running on a particular instance, filtered to only IIS processes
    $ProcessListSplat = @{
        ResourceGroupName = $ResourceGroup
        ResourceType = "Microsoft.Web/sites/instances/processes"
        ResourceName = "$AppServiceName/$($Instance.Name)"
        ApiVersion = "2018-11-01"
    }
    $ProcessList = Get-AzResource @ProcessListSplat | Where-Object { $_.Properties.Name -eq "w3wp" }

    foreach ($Process in $ProcessList) {
        $ProcessWithPropertiesSplat = @{
            ResourceGroupName = $ResourceGroup
            ResourceType = "Microsoft.Web/sites/instances/processes"
            ResourceName = "$AppServiceName/$($Instance.Name)/$($Process.Properties.id)"
            ApiVersion = "2018-11-01"
        }                       
        $ProcessWithProperties = Get-AzResource @ProcessWithPropertiesSplat

        # 'is_scm_site' is a property which is set on the Kudu worker process, which you don't want to restart
        if ($ProcessWithProperties.Properties.is_scm_site -ne $true) {
            Write-Verbose -Message "Instance ID $($Instance.Name) has computer name $($ProcessWithProperties.Properties.environment_variables.COMPUTERNAME)"

            Write-Verbose -Message "Going to stop process with PID $($ProcessWithProperties.Properties.Id)"

            # Remove-AzResource stops the IIS process, which will then automatically restart
            $Result = Remove-AzResource -ResourceId $ProcessWithProperties.ResourceId -ApiVersion 2018-11-01 -Force

            if ($Result -eq $true) { 
                Write-Verbose -Message "Process $($ProcessWithProperties.Properties.Id) stopped"
            }
            else {
                Write-Error -Message "Problem stopping process $($ProcessWithProperties.Properties.Id) on instance $($Instance.Name)."
                $FailedRestarts = $true
            }

            if ($InstanceCounter -lt $ApplicationInstances.Count) {
                Write-Verbose -Message "Sleeping for $SecondsBetweenRestarts seconds before next reboot..."
                Start-Sleep -s $SecondsBetweenRestarts
            }
        }
    }
}

if ($FailedRestarts) {
    throw "At least one restart failed. Please review output for details."
}