Compatibility with libkrun

[nohajc]

Is it possible to use this with libkrun? There are references to krunkit in the README but I'm using the C API directly.

Trying to find out if I can switch from gvproxy in order to assign a distinct IP to every VM and have it directly reachable from the host without port forwarding of guest services.

[nirs]

krunkit is just a wrapper over libkrun so you can use vmnet-helper with libkrun - your process need to do this same libkrun calls as krunkit.

Check how krunkit creates the virtio-net interface.

With krunkit we have:

program (minikube)
|
+- vment-helper --fd=3
+- krunkit --device virtio-net,type=unixgram,fd=4,mac=...

With libkrun we will have:

your program
|
+- vment-helper --fd=3

So your program should:

1. Create a socketpair
2. fork
3. exec vment-helper with one file descriptor
4. create the libkrun virtio-net interface with the second filedescriptor

Or as alternative, use file descriptor 4 in your program usn libkrun, and run your program with vmnet-client:
https://github.com/nirs/vmnet-helper?tab=readme-ov-file#using-vmnet-client

The nice thing about vmnet-client is that it is a supervisor string both programs for you, waiting until they terminate, terminating both of them if one fails, and termating both of them when you terminate it.

[nohajc]

Thank you for the high level steps. I'll give it a try!

[nohajc]

Works as expected. I was able to connect to my host network and the internet from a libkrun VM.

[nirs]

Feel free to add an issue for adding example libkrun integration.

[nirs]

@nohajc do you want to contribute a libkrun integration example? It can be a minimal C or Rust program that shows the networking details.

[nohajc]

I should be able to. Although I couldn't make it work with offloading yet. Probably a configuration error because it works with krunkit, right?

Also I was testing with a FreeBSD guest. I will try Linux too.

[nirs]

For offloading you need to enable offloading in libkrun (via virtio flags), and in the vmnet-helper you need to add --enable-tso --enable-checksum-offload.

If you are using the vmnet-client the offloading options are not available. You can contribute a fix to add these options.

[nohajc]

Thank you, I'm using the helper directly and I set the feature flags on both sides. I suspect it might just not work the same in BSD. I'm going to try Linux and report back.