MTU setting not honoured for bridge device

[Daniel Axtens]

I have the following /etc/netplan/10-bridge.yaml, based on the example in the netplan(5) man page.

network:
    version: 2
    ethernets:
        br0devs:
             match:
                name: ens[78]
             mtu: 1280
    bridges:
        br0:
            interfaces: [br0devs]
            addresses:
                - 10.10.10.2/24

The only other file in /etc/netplan is 50-cloud-init.yaml which only touches ens3.

I expect that the MTU of the ens7 and ens8 are 1280.

They are not:

ubuntu@bridgevm:~$ ip l
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 52:54:00:5a:61:16 brd ff:ff:ff:ff:ff:ff
3: ens7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UP mode DEFAULT group default qlen 1000
    link/ether 52:54:00:b7:08:53 brd ff:ff:ff:ff:ff:ff
4: ens8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UP mode DEFAULT group default qlen 1000
    link/ether 52:54:00:60:f3:ec brd ff:ff:ff:ff:ff:ff
5: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 32:86:59:06:1b:ec brd ff:ff:ff:ff:ff:ff

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: nplan 0.30
ProcVersionSignature: User Name 4.13.0-32.35-generic 4.13.13
Uname: Linux 4.13.0-32-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
Date: Tue Jan 30 13:35:50 2018
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: nplan
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel Axtens (daxtens)]

It looks like this is a duplicate of https://bugs.launchpad.net/ubuntu/+source/nplan/+bug/1724895

Closing.