After a lot of discussions with other colleagues in the end-user computing space (Yes you know who you are!)
There has been a lot of questions around Citrix and Azure Stack and what can we actually deliver there today? Therefore I wanted to write this blogpost to explain the current limitations and what we can actually deliver when it comes to Citrix on Azure Stack as it is now, before the general availability. One thing to note however is that the restrictions here are mostly from the Microsoft side of things as it is on platform now.
So I have described most of the Azure Stack platform and architecture in my previous blogpost found here –> http://msandbu.org/what-is-azure-stack-and-want-is-the-architecture/
Now on thing I wanted to point out is that since Azure Stack wants to mimic public Azure is also means that it has the same limitations as Azure especially when it comes to networking capabilities, but ill get back to that later. The best way to describe how Citrix can be used with Azure Stack is to describe how it can integrate with Azure today and take it from there.
Citrix has multiple services which can be provisioned in Azure today using the Azure marketplace. Which is Sharefile, Unidesk, NetScaler, XenApp trial and the Essentials services
Networking and marketplace challenges:
None of these marketplace offerings are available today in the AzureStack marketplace, even if Microsoft now has syndication enabled which allows us to download “pre-approved” services into Azure Stack and publish it to tenants. As of now there are quite limited number of items available in the syndicated marketplace. So Citrix needs to get the process going, since that is the only way that we can get NetScaler in there properly since it is running a custom firmware. We can of course download a NetScaler provisoined instance in Azure and import it to Azure Stack but that is a quite cumbersome process. The second part if we managed to get NetScaler up and running in Azure Stack we would still have the same limitations when setting up a HA pair we would need a Azure load balancer in front since GARP does not work in Azure Stack. GSLB would not be supported as well since it is not support in public azure (before the multi NIC / IP which came last week)
Of course NetScaler support and access to the enviroment could still be done using NetScaler Gateway as a Service
Also the XenApp 7.13 trial template which is available in marketplace might use a newer ARM API version which also is not available in Azure Stack as of now (AzureStack API version = api-version=2015-01-01) and that also uses Azure Automation for some pieces as well which is not included in Azure Stack. Which means that even if Citrix published the XenApp 7.13 trial on the marketplace syndication option we might not be able to use it properly.
However we can build our own service template that we can publish in the marketplace.
Citrix has been great on adding support for Azure Resource Manager when it comes to MCS resource provisioing and support for premium disks and the different virtual machine instances. As of now Citrix has a hard-coded integration with public Azure using a subscription ID, and it cannot therefore be integrated with Azure Stack completely as of now. Which means we would not have the hypervisor integration and therefore cannot do single image management properly using Citrix studio as we can with public Azure.
Might be that Citrix needs to create a custom resource provider to link into hypervisor directly to be able to properly provision resources.
And of course the final piece is if you are using Citrix with GPU. Public Azure published the N-series end of last year, which gives public Azure GPU-passtrough capabilities using DDI feature in Windows Server 2016. These virtual machine instances called N-series will not be available on Azure Stack (It only has A, D, and D2 series instances) which means you will not be able to deliver GPU support for Citrix servers running on Azure Stack.
We could of course still use another part of the infrastructure to deliver the GPU-based desktops such as Hyper-V/XenServer/VMware the only issue is that we cannot directly bridge the gap between the tenant workloads running on AzureStack across to for instance a vSphere cluster. The issue is here is that AzureStack does not allow us to stretch the VXLAN traffic to another part of the infrastructure.
Now we are still far away from the GA on Azure Stack from Microsoft, so it will be interesting to see what Citrix has in terms of a strategy for adding capabilities against Azure Stack. There are some limitations as of now that you should be aware of but these might change!