Hi!
Are there any machine events that you can subscribe to, like an OnMachineStatusChanged or something? I have a minimum server count of 0, so when I begin testing and there’s no machines listed, there’s like 2-5 min wait for a machine to boot up and be provisioned after I send an allocation request, and the only way to get the machine’s status (that I’m aware of), is to poll the ‘List Machines’ endpoint from the Admin REST API. Any help would be appreciated.
Try using the MultiplayEventCallbacks from the SDK. 
These events occur after a machine has already been provisioned. I have ‘Start on provision’ enabled so according to the docs:
“If the start on provision setting is enabled, Game Server Hosting starts game servers after provisioning the machine they exist on.” (source)
So the multiplay event callbacks cannot tell me the current status of a machine (such as BOOTING/ONLINE etc.) until the machine is already online - unless I’m mistaken?