Powershell for an Advanced Application Restart on an Azure Web App

Question

It is possible to use Restart-​Azure​Rm​Web​App PowerShell to restart a web app but this will restart all servers in the plan simultaneously, giving a short downtime.

The Azure Portal has an "Advanced Application Restart" feature that uses a time delay between restarting individual instances.

Is there any way to invoke that from PowerShell?

Answer 1

According to your description, I suggest you could firstly find each instance's process in your web app by using Get-AzureRmResource command. Then you could use Remove-AzureRmResource to stop these processes. Then when you access the azure web application, azure will automatic create new instance's process to run your application.

More details, you could refer to below powershell codes:

Login-AzureRmAccount
Select-AzureRmSubscription -SubscriptionId '{your subscriptionid}'

$siteName = "{sitename}"
$rgGroup = "{groupname}" 

$webSiteInstances = @()

#This gives you list of instances
$webSiteInstances = Get-AzureRmResource -ResourceGroupName $rgGroup -ResourceType Microsoft.Web/sites/instances -ResourceName $siteName -ApiVersion 2015-11-01 

$sub = (Get-AzureRmContext).Subscription.SubscriptionId 

foreach ($instance in $webSiteInstances)
{
    $instanceId = $instance.Name
    "Going to enumerate all processes on {0} instance" -f $instanceId 

    # This gives you list of processes running
    # on a particular instance
    $processList =  Get-AzureRmResource `
                    -ResourceId /subscriptions/$sub/resourceGroups/$rgGroup/providers/Microsoft.Web/sites/$sitename/instances/$instanceId/processes `
                    -ApiVersion 2015-08-01 

    foreach ($process in $processList)
    {               
        if ($process.Properties.Name -eq "w3wp")
        {            
            $resourceId = "/subscriptions/$sub/resourceGroups/$rgGroup/providers/Microsoft.Web/sites/$sitename/instances/$instanceId/processes/" + $process.Properties.Id            
            $processInfoJson = Get-AzureRmResource -ResourceId  $resourceId  -ApiVersion 2015-08-01                                     

            # is_scm_site is a property which is set
            # on the worker process for the KUDU 

                $computerName = $processInfoJson.Properties.Environment_variables.COMPUTERNAME

                if ($processInfoJson.Properties.is_scm_site -ne $true)
            {
                $computerName = $processInfoJson.Properties.Environment_variables.COMPUTERNAME
                "Instance ID" + $instanceId  + "is for " +   $computerName

                "Going to stop this process " + $processInfoJson.Name + " with PID " + $processInfoJson.Properties.Id

                # Remove-AzureRMResource finally STOPS the worker process
                $result = Remove-AzureRmResource -ResourceId $resourceId -ApiVersion 2015-08-01 -Force 

                if ($result -eq $true)
                { 
                    "Process {0} stopped " -f $processInfoJson.Properties.Id
                }
            }       
       }

    }
}

Result: