libvirt default network is broken

[d4g]

Describe the bug
Libvirt usually handles virtual network devices, interfaces, bridges and also the DHCP range. This seems to be broken.

To Reproduce
Steps to reproduce the behavior:

1. Start a VM connected to the default network
2. Don't get an IP

Expected behavior
DHCP is working

Screenshots
If applicable, add screenshots to help explain your problem.

Notify maintainers
@fpletz
@grahamc
@offlinehacker

Metadata
Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

• system: "x86_64-linux"
• host os: Linux 5.10.6-zen1, NixOS, 21.03pre263901.68398d2dd50 (Okapi)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.10
• channels(root): "nixos-21.03pre263901.68398d2dd50"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixos modules affected by the problem
module:
  libvirt

[mohe2015]

@d4g Likely fixed by #109722. If you are fine with rebuilding libvirt your could use this locally. Alternatively if this is your home computer and you are in a safe network you could temporarily set networking.firewall.enable = false; to disable your whole system's firewall but this is not recommended.

Edit: Rebuliding should be really quick (on a decent laptop)

[d4g]

Thanks @mohe2015 - looks right. I will try to use the overlay first.

[tfmoraes]

I think it's related... When I try to start a VM using Gnome-boxes or Virtual-manager with VM using bridge this error happens:

Erro ao iniciar o dominio: internal error: /run/wrappers/bin/qemu-bridge-helper --br=virbr0 --fd=33: failed to communicate with bridge helper: Transport endpoint is not connected
stderr=failed to parse default acl file `/nix/store/2h7s274cwhw708giflvr1p3329ypm3vr-qemu-5.2.0/libexec/../etc/qemu/bridge.conf'


Traceback (most recent call last):
  File "/nix/store/dhn1d3f5pwgqzzkjzl6miyfz09hcr5pb-virt-manager-3.1.0/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/nix/store/dhn1d3f5pwgqzzkjzl6miyfz09hcr5pb-virt-manager-3.1.0/share/virt-manager/virtManager/asyncjob.py", line 101, in tmpcb
    callback(*args, **kwargs)
  File "/nix/store/dhn1d3f5pwgqzzkjzl6miyfz09hcr5pb-virt-manager-3.1.0/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn
    ret = fn(self, *args, **kwargs)
  File "/nix/store/dhn1d3f5pwgqzzkjzl6miyfz09hcr5pb-virt-manager-3.1.0/share/virt-manager/virtManager/object/domain.py", line 1330, in startup
    self._backend.create()
  File "/nix/store/c2k97p6l7w3ga58slpzlc84ca9djl2df-python3.8-libvirt-6.8.0/lib/python3.8/site-packages/libvirt.py", line 1334, in create
    raise libvirtError('virDomainCreate() failed')
libvirt.libvirtError: internal error: /run/wrappers/bin/qemu-bridge-helper --br=virbr0 --fd=33: failed to communicate with bridge helper: Transport endpoint is not connected
stderr=failed to parse default acl file `/nix/store/2h7s274cwhw708giflvr1p3329ypm3vr-qemu-5.2.0/libexec/../etc/qemu/bridge.conf'

[mohe2015]

@tfmoraes have you updated to the latest nixos-unstable version? This issue itself should be fixed and you should probably create a new issue if your problem persists.

[tfmoraes]

@mohe2015 it's still happening, even with the last version.

[mohe2015]

@tfmoraes then you should probably create a new issue as I don't think it's the same issue. It may still be related so maybe reference this issue. There wasn't an error with the original issue I think