** 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
+ # mkdir -p /tmp/np_backup/etc/ && cp -r /etc/netplan /tmp/np_backup/etc/
# netplan set network.bridges.br54=null
# netplan get # check that br54 is NOT present
- # netplan apply --state /etc/netplan_backup
+ # netplan apply --state /tmp/np_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.
** Changed in: netplan.io (Ubuntu Focal)
Status: New => In Progress
** Changed in: netplan.io (Ubuntu Focal)
Assignee: (unassigned) => Simon Chopin (schopin)
** Changed in: netplan.io (Ubuntu Hirsute)
Assignee: (unassigned) => Simon Chopin (schopin)
** Changed in: netplan.io (Ubuntu Hirsute)
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1943120
Title:
interface not removed
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