The lab involved SCVMM Service Templates, a custom Windows Azure Pack Gallery Image, and a Desired State Configuration module.
I had my environment of Hyper-V 2012 R2, SCVMM 2012 R2, and WAP about 95% configured. As much as I could and still support the students re-using my VMs with their own Hyper-V Server.
Since the lab was not about WAP, but instead about my gallery image, I wanted to keep it as simple as possible. I had a cloud, the cloud had a VM Network assigned, the students created a static IP pool.
(I already had an Internal Virtual Switch being created by SCVMM as a Logical Switch so that all lines of dependency were properly drawn)
In the WAP Admin portal - I had the students add the cloud and the VM Network to their plan.
I deploy my Gallery Image, and the domain join failed.
I look closer, and I see that my VM ended up with an APIPA address and not an address from the IP Pool.
Come to find out, the default behavior of a WAP Gallery Image is for dynamic IP address assignment.
Which, if you only ever deploy a gallery image to a Windows Network Virtualization VM Network, you will never notice. You will instead see that you get an IP from the IP Pool.
Something that I discovered long ago was that there is a custom Hyper-V Virtual Switch extension that ships with SCVMM. It is actually a DHCP responder. It catches the IP request, notifies SCVMM, and SCVMM responds with an IP from the SCVMM IP Pool assigned to the VM. Nifty.
But, this path only happens if the VM is attached to a Windows Network Virtualization (NVGRE) network managed by SCVMM.
Back to the default Gallery Image behavior of a dynamic IP address. No WNV network, no IP from an IP Pool. How to fix this?
The only way to fix this is to open the Resource Definition of the Gallery Image, and then open the Network Profile, then the NIC.
And change the AllocationMethod to Static.
But the thing to be aware of is this, these are hard coded values, unless you work through making them settings that are actually exposed to your end customer (at this time you can't expose these settings).
If you change a setting here, that makes a dependency on an SCVMM placement rule, SCVMM will have to find a place that this VM can go to support all of the settings. If it cannot, your VM will not be deployed. And your tenant will call.