thanks for fixing this. The PR looks sound. I have a few trouble with my nixops setup at the moment but I will try to give it a run next week !

I am concerned abouyt the removal of nix/libvirtd-image.nix . I have pending changes that make use of qemuGuest in libvirtd-image.nix . If this gets removed, where am I supposed to move the declaration

@teto Can you show me your modifications? I couldn't find them in your pull requests or in github.com/teto/nixops.

for instance this line is new (the filename has changed but it's the same : https://github.com/teto/nixops/blob/ad4c1866b88075bd6b28d2c9f4e39d74a8ca2027/nix/libvirtd/image.nix#L22).
It would be nice to keep having some libvirtd specific configuration ? even though this might be a bad example as it's useful outside libvirt, as soon as we use qemu in fact.

We have libvirtd specific options also with the new image builder. Just stick "services.qemuGuest.enable = true;" to the bottom of the file in libvirtd.nix inside the config set. The image builder will pick that up, because the "config" option passed into the function call as "config = config" is derived from the config specified on the bottom of the file (it comes back in via a funciton argument at the top of the file, at least that's my understanding.)

this looks good, can we merge ?

From my point of view, yes :)

Now that nixops backends are implemented as plugins, you should reopen the PR against https://github.com/nix-community/nixops-libvirtd (I believe).

Meh, sorry. I don't feel like testing this again. I'll drop the PR entirely and keep nixops as is locally.