At VaiSulWeb virtualization is so pervasive that basically there aren’t physical machines other than virtualization hosts or storage since about 2008 or 2009. That means about 10 years now. And counting. Microsoft Hyper-V served us very well and over time our reliance on that technology increased with happy results. It has been solid and consistent and allowed us to scale up more and more, adding new technologies and solutions and enabling us to virtualize roles and workloads that seemed a bit difficult to virtualize.

As many other providers, we recently started integrating AMD CPUs into our infrastructure, given the terrific advantages that those could bring to the datacenter especially for generic or mixed workloads. Only a subset of our infrastructure has been migrated to the new AMD servers but things got easier because of the many advantages that the Windows Server (+ Hyper-V) platform could provide and we carefully started to fill those hosts by migrating workloads. Results have been very pleasing.

Performance improvements and security

As we had planned, we immediately started benefiting of performance improvements. Not only CPU-bound tasks were faster but also I/O performance were terrific.

One of our goals was also to improve security by using AMD technologies that showed better resiliency when dealing with security issues when compared to Intel chipsets and CPUs and we were also prepared to face a few limitations. For example, Hyper-V isolated containers are not supported on non-Intel CPUs and thus cannot be used.

We started migrating our workloads to the new servers and Hyper-V functionalities like shared-nothing live migration and live migrations made the process quite easy and straightforward. In a few days about 80% of the target workloads have been migrated with minimal or no disruption at all. So far so good.

Unexpected crashes

Then something odd happened: one of the hosts started to crash. That was surely something we rarely faced in our 10+-years-long experience with Hyper-V but that specific host was crashing up to 2-3 times per day and while it usually was back online in about 2 minutes with all of its VMs restarted, the virtual machines that it was hosting were obviously also crashing causing downtimes. That was very surprising since similar machines (basically identical since they were using the same components) were not exhibiting any issue even after running for weeks in production and even more in our labs.

That machine had been running for days without issues then started crashing 2-3 times per day with no traceable pattern. Sometimes it could run for hours (10 or more) without issues, sometimes it was crashing two times in 15 minutes. Weird. And scary.

We decided to halt our migration to ensure that we didn’t miss any incompatibility between Windows Server 2019 and those AMD servers yet other servers were not having any issue and tracing back the issues we had, that specific machine had not been exhibiting issues for days before it started crashing so often.

Diagnosing the issues

The first thing that you might want to do in such cases is to ensure [...]

Microsoft is investing a lot into its new Server Manager though Redmond is not encouraging that parallelism and often says that Windows Admin Center is not a 1-to-1 replacement for Server Manager. That is true because Server Manager and its underlying technology has a deeper connection with the operating system and it can be considered a platform while Winows Admin Center can be considered a very sophisticated shell that mostly works through WMI/Powershell connections.

However, Windows Admin Center is gaining a lot of traction and it’s quickly gaining support because its Web UI allows to embed important tasks into simple to access and to use widgets called tools and access them through a simple browser. Productivity is enhanced especially when used with the Core version of Windows operating systems and I’m not surprised that Microsoft is experiencing a growth in adoption for the Core SKUs because of it.

Why containerizing Windows Admin Center ?

So the first question would be: why would someone want to containerize Windows Admin Center ? First, a containerized WAC would be very easy to deploy on multiple systems in a very straightforward way. Furthermore, multiple copies of WAC, possibly in use by different teams, could be deployed and used thanks to the isolation provided by containers and their flexibility. Containers could be also useful to mitigate any security issue that could arise even if Windows Admin Center showed no security vulnerabilities as far as I know. Finally, by using Hyper-V isolation multiple instances of WAC could be isolated and provided to multiple tenants.

Prepare the environment

To deploy WAC into a container we will use Windows Server 2019. We must first enable containers support by selecting and adding the feature in Roles&Features section of Server Manager:

Then we must install Docker as per Microsoft Docs :

Install-Module -Name DockerMsftProvider -Repository PSGallery -Force

and then

Install-Package -Name docker -ProviderName DockerMsftProvider

and finally restore Windows Server 2019 to complete installation

Restart-Computer -Force

When server restarts we can pull the Windows Server 2019 Core image that we will use to run Windows Admin Center. Note that WAC doesn’t need IIS because it will self-host so downloading the base OS image will be enough

docker pull mcr.microsoft.com/windows/servercore:ltsc2019

After downloading the image we are now ready to spin our new container and install Windows Admin Center.

Create the WAC container

We have a choice to make before creating the container for WAC and that is the port we want to expose WAC onto. That would be the port we connect to in order to use WAC. To make our life easier now, we will expose this port to the host but more sophisticated deployments might be appropriate depending on what you’re trying to achieve. We need to decide that first because we will then need this information when installing Windows Admin Center. We will make it available on port 8443.

docker run -it -p 8443:8443 mcr.microsoft.com/windows/servercore:ltsc2019 cmd.exe

If everything goes well you will have CMD prompt ready after starting the container. Now we need to copy the installation files into the container. You probably downloaded [...]

If you’re anything like me, virtualization has a great and important role in your everyday work. I use to virtualize most of my development machines, with Visual Studio and the whole stack. That allows me to avoid reconfiguring the environments whenever I need to switch my main machine, plus you get all the benefits of virtualization like for example the ability to backup the whole machine and move it elsewhere.

Up until now, such deployments had just one limitation: you could not use them to run mobile apps since nested virtualization was not supported on Windows 8 or Windows Server 2012 R2 so you could not run emulators that needed Hyper-V. Things changed with Windows 10 and Windows Server 2016 since nested virtualization is now allowed so I thought that was perfect chance to redeploy machines I used for mobile development into VMs.

So Visual Studio 2015 is running and Xamarin ready, you create a new Xamarin Forms project and you want to test that your environment is working fine. You start debug for the Android application but the Visual Studio Android emulator is not working. A “Hyper-V component is not running” :

Something happened while starting a virtual machine: ‘VS Emulator 5-inch KitKat (4.4) XXHDPI Phone.macoswin’ failed to start. (Virtual machine ID 77D02994-C4A1-4A43-9AE7-7E55C03521D4) The Virtual Machine Management Service failed to start the virtual machine ‘VS Emulator 5-inch KitKat (4.4) XXHDPI Phone.macoswin’ because one of the Hyper-V components is not running (Virtual machine ID 77D02994-C4A1-4A43-9AE7-7E55C03521D4). _

Hyper-V seems to be working fine plus it has been installed, something that never succeeded in past Windows (Server) versions but emulators don’t work. The reason for this is your host is not enabling all Hyper-V features to the guest machine. That’s probably related to the fact that Hyper-V is also needed for Containers but I’m not sure about that.

Turns out that you need to tell host that you want to expose ALL Hyper-V functionalities if you want to enable full nested virtualization so you have to log into the host (which might simply be your own notebook or desktop PC or even a Surface Pro, like in my case) and run this command using an elevated shell:

Set-VMProcessor -VMName <VMName> -ExposeVirtualizationExtensions $true

<VMName> obviously is the name of the virtual machine that you want to enable nested virtualization for. Also ensure that such VM has been shut down (no saving, no suspension). Once you reboot, emulators will start working. You might need to re-deploy the emulators VMs just to ensure that everything will be redeployed in a smooth way. You simply need to delete those emulators inside Hyper-V Manager.

The problem is: when you will deploy your test app – even the simplest one, the one generated by the template – it will not run inside the emulator. It just starts and shuts down almost instantly, probably crashing.

To fix this problem, you need to change a setting in the virtual machine that is hosting Visual Studio and the emulators as well:

Again, you need to shut the VM down before changing [...]