How to identify this provider from within an instance

Is there a way for an Ubuntu 14.04 instance to tell whether it’s running at this provider, as opposed to some other provider or in VirtualBox on my laptop, etc?

I realize that the provider could be identified via the startup script, that could “bake” that information into the instance when it’s created. Or some external software could log into the instance and configure it accordingly. That’s doable.

But I was wondering if there’s a simple, unambiguous way for an instance that’s already running, to tell that it’s running at this provider, using only things that are already available to it.

I don’t want to do an API call, download the list of instances, and have this instance try and identify itself in the list. There must be a simpler way, like the existence of a provider-specific package in the OS, or something like that. The test must be reliable and simple.

Thanks.