Here is a full procedure to reproduce the issue. Set-up ======
1. Install an amd64 Debian Buster (default network install), 2. install lxc and create a bionic amd64 container, ```bash apt install lxc lxc-create -t download -n bionic lxc-start -n bionic ``` 3. inside the container, deactivate dhcp (dhcp4: false )in `/etc/netplan/10-lxc.yaml`, and install the systemd packages without the bug, ```bash lxc-attach -n bionic sed -i 's/true/false/' /etc/netplan/10-lxc.yaml apt install systemd=237-3ubuntu10.38 libsystemd0=237-3ubuntu10.38 libnss-systemd=237-3ubuntu10.38 libpam-systemd=237-3ubuntu10.38 exit ``` 4. create a bridge on the host with a static IP and deactivate dhcp, in `/etc/network/interfaces`, ``` # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). source /etc/network/interfaces.d/* # The loopback network interface auto lo iface lo inet loopback ## The primary network interface #allow-hotplug ens18 #iface ens18 inet dhcp ## This is an autoconfigured IPv6 interface #iface ens18 inet6 auto iface ens18 inet manual auto br0 iface br0 inet static address 192.168.1.168 netmask 255.255.255.0 gateway 192.168.1.220 bridge_ports ens18 bridge_stp off bridge_waitport 0 bridge_fd 0 ``` 5. on the host, modify the network configuration of the container to use the bridge with a static IP in `/var/lib/lxc/bionic/config`, ``` # Template used to create this container: /usr/share/lxc/templates/lxc-download # Parameters passed to the template: # Template script checksum (SHA-1): 273c51343604eb85f7e294c8da0a5eb769d648f3 # For additional config options, please look at lxc.container.conf(5) # Uncomment the following line to support nesting containers: #lxc.include = /usr/share/lxc/config/nesting.conf # (Be aware this has security implications) # Distribution configuration lxc.include = /usr/share/lxc/config/common.conf # For Ubuntu 14.04 lxc.mount.entry = /sys/kernel/debug sys/kernel/debug none bind,optional 0 0 lxc.mount.entry = /sys/kernel/security sys/kernel/security none bind,optional 0 0 lxc.mount.entry = /sys/fs/pstore sys/fs/pstore none bind,optional 0 0 lxc.mount.entry = mqueue dev/mqueue mqueue rw,relatime,create=dir,optional 0 0 lxc.arch = linux64 # Container specific configuration lxc.apparmor.profile = generated lxc.apparmor.allow_nesting = 1 lxc.rootfs.path = dir:/var/lib/lxc/bionic/rootfs lxc.uts.name = bionic ## Network configuration #lxc.net.0.type = empty # Network configuration lxc.net.0.type = veth lxc.net.0.flags = up lxc.net.0.link = br0 lxc.net.0.name = eth0 lxc.net.0.ipv4.gateway = 192.168.1.220 lxc.net.0.ipv4.address = 192.168.1.169/32 ``` 6. reboot the host. ```bash reboot ``` Let’s do it =========== 1. Start the container and check the IP config, which should be ok, ```bash lxc-start -n bionic lxc-attach -n bionic ip a ``` 2. upgrade the system and check the IP config, the static is gone. ```bash apt upgrade ip a exit ``` If systemd is downgraded again to 237-3ubuntu10.38, the IP is back at the next reboot of the container. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1863873 Title: Systemd fails to configure bridged network in LXC container To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1863873/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs