** Description changed: + [Impact] + + Virtual devices such as bridge interfaces that are created via netplan + aren't destroyed when they are removed from the active netplan + configuration. + + This is a known issue and has been the case for a long time: + http://manpages.ubuntu.com/manpages/focal/man8/netplan-apply.8.html#known%20issues + + It is problematic as it can break network connectivity when doing + `netplan apply` even though the netplan configuration itself might be + correct, leading the user to search for an issue that isn't there. + + This patch only brings a workaround, by allowing the user to manually + provide the previous configuration, which netplan will use to see what + the diff is. + + [Test Plan] + + On a VM, assuming no bridge interface is configured: + + # netplan set network.bridges.br54.dhcp4=false + # netplan get # check that br54 is present + # netplan apply + # ip link show br54 && echo OK + # cp -r /etc/netplan /etc/netplan_backup + # netplan set network.bridges.br54=null + # netplan get # check that br54 is NOT present + # netplan apply --state /etc/netplan_backup + # ip link show br54 && echo ERROR + + [Potential Problems] + + As usual, any netplan upgrade has the potential of breaking the user's + network setup. + + This patch could make things worse: it's conceivable that with these + changes, `netplan apply --state backup` could result in a working system + but the configuration applied at startup wouldn't be correct. Indeed, + the delta between the `apply` codepath and what is run at startup grows + larger with this change. + + [Original report] + While working on the UC20 integration for netplan I ran into the follow, I may misunderstand how netplan dbus works so feel free to close as "Invalid" if it's my misconception (and apologizes in this case). Any help appreciated. I ran into this while writing integration tests for snapd netplan integration, I create (via the dbus api) a bridge br54, set it to dhcp and then unset the interface again. After unset the br54 interface is still available but AIUI it should be deleted. Attached is a reproducer that uses the same dbus api as snapd is using. I ran it on a fresh 21.04 VM and got the same issue so it's probably not UC20 specific. If I do similar things using "netplan set/netplan try/netplan appy" directly it seems that the interface gets deleted as expected. I did not write a script for this though, just manually tried it so I might be wrong here.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1943120 Title: interface not removed To manage notifications about this bug go to: https://bugs.launchpad.net/netplan/+bug/1943120/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
