How to Get Azure App Service Windows Worker OS Full Name and Version

Background

Sometimes, it's crucial to know the underlying operating system running your Azure App Service. This can help you address compatibility issues during development before deploying to Azure. Unfortunately, Microsoft's documentation does not specify the exact operating system name and version of the Web Worker that runs your application. So, it's up to us to determine this information.

It's important to note that there is no guarantee that all Azure App Service Web Workers are running the same operating system. For instance, during the migration from Windows Server 2016 to 2022, which spanned nearly a year, App Service scale units were upgraded gradually. This means that some servers received the new operating system sooner than others. Which means, the information provided in this blog post might not reflect the system you are using. Always verify the details for your specific environment.

Solution

Just the version number

The typical way for getting Windows OS version is to run the ver command, which also works in the App Service console.

In case you don't know, the console is located in the side menu of your App Service instance.

Most of the time, this would be enough to determine what's the Windows Version, according to this table:

Get the OS full name

If you want to get the friendly name, like "Windows Server 2022", all your favorite commands will blow up:

Even in PowerShell:

In case you don't know, you can get the PowerShell console from the "Advanced Tools" menu in your App Service instance.

Get-ComputerInfo | Select-Object CsName, OsName, WindowsVersion, WindowsBuildLabEx

(Get-WmiObject -Class Win32_OperatingSystem).Caption

The workaround is to read Windows registry. Registry path HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProductName holds the information of the OS full name.

To read a registry value using PowerShell, you can use the Get-ItemProperty cmdlet. 

$regPath = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion"
$productName = Get-ItemProperty -Path $regPath -Name "ProductName"
$productName.ProductName

Using the same trick, we will also be able to get the server system version from the code of the App that we deploy to Azure App Service, like my ASP.NET Core blog system:

public static string TryGetFullOSVersion()
{
    var osVer = Environment.OSVersion;
    if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) return osVer.VersionString;

    try
    {
        var currentVersion = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
        if (currentVersion != null)
        {
            var name = currentVersion.GetValue("ProductName", "Microsoft Windows NT");
            var ubr = currentVersion.GetValue("UBR", string.Empty).ToString();
            if (!string.IsNullOrWhiteSpace(ubr))
            {
                return $"{name} {osVer.Version.Major}.{osVer.Version.Minor}.{osVer.Version.Build}.{ubr}";
            }
        }
    }
    catch
    {
        return osVer.VersionString;
    }

    return osVer.VersionString;
}

<td class="text-muted">@Helper.TryGetFullOSVersion() @(Environment.Is64BitOperatingSystem ? "(64-bit)" : "(32-bit)")</td>