IncludeOS: a minimal, resource efficient unikernel for cloud services

IncludeOS is an includable, minimal unikernel operating system for C++ services running in the cloud and on real HW. Starting a program with #include <os> will literally include a tiny operating system into your service during link-time.
↫ IncludeOS GitHub page

IncludeOS isn’t exactly the only one of its kind, but I’ve always been slightly mystified by what, exactly, unikernels are for. The gist is, as far as I understand it, that if you build an application using a unikernel, it will find out at compile time exactly what it needs from the operating system to run, and then everything it needs from the operating system to run will be linked inside the resulting application. This can then be booted directly by a hypervisor.

The advantages are clear: you don’t have to deal with an entire operating system just to run that one application or service you need to provide, and footprint is kept to a minimum because only the exact dependencies the application needs from the operating system are linked to it during compilation. The downsides are obvious too – you’re not running an operating system so it’s far less flexible, and if issues are found in the unikernel you’re going to have to recompile the application and the operating system bits inside of it just to fix it (at least, I think that’s the case – don’t quote me on it).

IncludeOS is under heavy development, so take that under advisement if you intend to use it for something serious. The last full release dates back to 2019, but it’s still under development as indicated by the GitHub activity. I hope it’ll push out a new release soon.