Error starting instance with unmanaged bridge about `ovs-vsctl` not being found

LXD
2

I think I figured out my problem. My “bridge” interface mylxdbr0 was not an actual bridge interface, so LXD didn’t know what to do with it.

I figured this out by somewhat aimlessly clicking around the LXD source code. I found:

This made me think that LXD expects bridges to have a /sys/class/net/%s/bridge directory available. I checked /sys/class/net/mylxdbr0/bridge and it did not exist.

I had created this mylxdbr0 interface with the following NixOS config:

networking.interfaces.mylxdbr0 = {
  name = "mylxdbr0";
  virtual = true;
  useDHCP = false;
  ipv4.addresses = [ { address = "192.168.57.1"; prefixLength = 24; } ];
  ipv4.routes = [ { address = "192.168.57.0"; prefixLength = 24; } ];
};

This causes the interface to get created with a command like:

$ ip tuntap add dev "mylxdbr0" mode "tun" user "root"

This tun interface is apparently not a bridge interface.

What I ended up doing that worked was:

networking.bridges = { mylxdbr0.interfaces = []; };

This causes the interface to get created with a command like the following:

$ ip link add name "mylxdbr0" type bridge

I then had to explicitly add an IP to my interface:

$ sudo ip address add 192.168.57.1/24 dev mylxdbr0

This enabled me to successfully run lxc start lxc-nixos:

$ lxc list
+-----------+---------+----------------------+------+-----------+-----------+
|   NAME    |  STATE  |         IPV4         | IPV6 |   TYPE    | SNAPSHOTS |
+-----------+---------+----------------------+------+-----------+-----------+
| lxc-nixos | RUNNING | 192.168.57.50 (eth1) |      | CONTAINER | 0         |
|           |         | 172.17.0.1 (docker0) |      |           |           |
+-----------+---------+----------------------+------+-----------+-----------+

I’m able to communicate between my host and the guest. Now all I need to do is figure out how to setup the NAT right so the guest can access the internet.

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