Bridge gets MAC address of most recently started container

LXD
1

Hi,

Here is a weird thing that just found out. I have a bridge, br0, that I have created outside LXD. This bridge contains the physical ethernet port, e.g eno1.
I’m using that bridge in a profile called default_pub. That profile is a copy of default, except that it uses br0 instead of lxdbr0.
All is fine and dandy. I can create containers that appear on my local network.
Before any container is started br0 has the MAC address of eno1. But when a container is started the bridge gets the MAC address of that container.

Is this normal for bridges? Maybe it is, but I’m quite surprised by it. Because on a new system I configured the bridge to get an IP address through DHCP. That system really gets confused when containers are started and stopped.

2

In the meantime I found something that could explain the things I’m seeing.

3

Yea its normal, but if you set the bridge manually (or via your oses network settings) it won’t change.

4

FYI The bridge is created through netplan / networkd.

$ cat /etc/netplan/00-installer-config.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    eno1:
      dhcp4: false
      dhcp6: false
  bridges:
    br0:
      interfaces: [eno1]
      addresses:
      - 192.168.1.35/24
      gateway4: 192.168.1.1
      nameservers:
        addresses:
        - 192.168.1.1
        search:
        - example.com

That is apparently not enough to get a fixed MAC address, because br0 had the MAC address of one of the containers.
So, now I added macaddress to br0, copied from eno1.

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