Maybe like me you want to quickly spin up a manual RDS farm so you jump in vCenter and clone an existing RDS image that has the Horizon Agent installed. The problem here is that when you go to add the host it’s not available in Horizon.
This can happen when performing a clone operation or building from a template that has the Horizon Agent installed. Luckily it’s straightforward to remediate.
The scenario I’m covering here happens when you create a virtual machine for published applications or desktops within VMware Horizon. Specifically when the Horizon agent was installed before you decided to clone the VM, which would have registered it with Horizon. This does not happen with Instant Clone pools/farms since they register as a part of the Horizon clone operation.
Sadly the agent in the clone doesn’t know how to re-register the new machine with Horizon. This can be a good reason to consider Instant Clone RDS Farms. Especially if you need several base images which would require multiple installs/reinstalls.
Resolution
The fix is to simply uninstall the Horizon Agent and then install the Horizon Agent again. Upon installation, the VM is able to freely make itself available in Horizon.
Login to the cloned RDSH base image that is not registering as an administrator. Navigate to Apps & features and click Uninstall under the VMware Horizon Agent.
A reboot will be required once the uninstall is complete. Reboot the machine and log back in as an administrator account.
Once you’re logged in run the Horizon Agent installer for the relevant version you need. I won’t cover the steps here, but you can reference the documentation. I do want to call out 2 steps. Since the scenario described here only happens when not using Instant Clones, be sure you unselect the Instant Clone option when configuring the agent.
If the previous step is correct then you will be presented with the Register with Horizon Connection Server option. Enter a connection server hostname or IP and this will force the VM to register itself again.
After completing the installation and rebooting the image should be available in Horizon.
