[Bug 1669564] Re: udevadm trigger subsystem-match=net doesn't always run rules

Dimitri John Ledkov launchpad at surgut.co.uk
Tue Mar 7 15:41:53 UTC 2017 

On 7 March 2017 at 14:37, Ryan Harper <1669564 at bugs.launchpad.net> wrote:
> On Tue, Mar 7, 2017 at 6:27 AM, Dimitri John Ledkov <launchpad at surgut.co.uk>
> wrote:
>
>> Should one not restart systemd-networkd after writing out .link et.al.
>> units?
>>
>
> systemd-networkd only deals with .netdev and .network files; .link files
> are handled by udev
>
>
> This occurs during boot, before systemd-networkd starts.
>
> cloud-init-local.service runs before network-pre.target and writes out a
> /etc/netplan/nplan.yaml,
> invokes `netplan generate` which writes out
> /run/systemd/network/10-netplan-xx.{.link,network,netdev}
> as needed; however, the cold plug of devices (systemd-udev-trigger.service)

does netplan rename the interfaces? this will then introduce a race,
ideally we'd want to rename interfaces only once.
(E.g. does udev in the initramfs rename interface from eth0 to e.g.
ens3, and then netplan's .link files rename enc3 again into something
else?)

> happens prior to
> cloud-init-local.service; as it's required for mounting the rootfs among
> other things.
>
> The udev service is also used for device renaming, which would need to
> occur before starting
> networkd.  As such, in cloud-init-local, after generating netplan
> configuration, we re-trigger
> the net subsystem events which *should* process any .link files.
>
> The bug, I believe, is that during cloud-init-local execution, udev does
> *not* process the .link files
> prior to starting systemd.
>

Is there a typo here, and/or can you rephrase this assertion?
cloud-init-local is a systemd unit therefore by definition systemd and
udev are running "during cloud-init-local execution".

The rest of the comment sort of makes sense.

> I'm currently working around this using the side-effect of using udevamd
> test-builtin setup_net_link
> which will process the .link files.
>
> I'll collect a journal and attach it.

-- 
Regards,

Dimitri.

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https://bugs.launchpad.net/bugs/1669564

Title:
  udevadm trigger subsystem-match=net doesn't always run rules

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  1. root at ubuntu:~# lsb_release -rd
  Description:    Ubuntu Zesty Zapus (development branch)
  Release:        17.04

  2. root at ubuntu:~# apt-cache policy udev
  udev:
    Installed: 232-18ubuntu1
    Candidate: 232-18ubuntu1
    Version table:
   *** 232-18ubuntu1 500
          500 http://archive.ubuntu.com/ubuntu zesty/main amd64 Packages
          100 /var/lib/dpkg/status

  3. udevadm trigger --verbose --subsystem-match=net --action=add will run and read .link files from /run/systemd/network/10-netplan-interface1.link
  and apply MTU settings

  4. during system boot running (3) does not set the MTU; running (3)
  after boot has completed MTU is set correctly.

  Here'a log during boot where cloud-init generates a netplan config,
  invokes `netplan generate` which writes the networkd config out 
  and then udevadm trigger (3).  Upon logging in interface1 has an MTU of 1500.  Re-running udevadm trigger now runs the rules/link files and updates the MTU.

  Note that, if you run udevadm test /sys/class/net/interface1; this also will
  apply the MTU (test probably shouldn't change the interface, I'll file a
  bug for that as well).

  # journalctl -o short-precise --no-pager -b | grep WARK
  Mar 02 19:17:19.839797 ubuntu cloud-init[647]: WARK: ['netplan', '--debug', 'generate']:
  Mar 02 19:17:19.839797 ubuntu cloud-init[647]: WARK: ['stat', '/run/systemd/network/10-netplan-interface1.link']:
  Mar 02 19:17:19.839797 ubuntu cloud-init[647]: WARK: ['cat', '/run/systemd/network/10-netplan-interface1.link']:
  Mar 02 19:17:19.839797 ubuntu cloud-init[647]: WARK: ['systemctl', 'start', '--no-block', 'systemd-udev-trigger.service']:
  Mar 02 19:17:19.839797 ubuntu cloud-init[647]: WARK: ['udevadm', 'trigger', '--verbose', '--subsystem-match=net', '--action=add']:

  root at ubuntu:~# cat /run/systemd/network/10-netplan-interface1.link
  [Match]
  MACAddress=52:54:00:12:34:02

  [Link]
  Name=interface1
  WakeOnLan=off
  MTUBytes=1492

  root at ubuntu:~# ifconfig interface1
  interface1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
          inet 10.0.2.100  netmask 255.255.255.0  broadcast 10.0.2.255
          inet6 fe80::5054:ff:fe12:3402  prefixlen 64  scopeid 0x20<link>
          inet6 fec0::5054:ff:fe12:3402  prefixlen 64  scopeid 0x40<site>
          ether 52:54:00:12:34:02  txqueuelen 1000  (Ethernet)
          RX packets 16  bytes 5053 (5.0 KB)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 35  bytes 3287 (3.2 KB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

  root at ubuntu:~# udevadm trigger --verbose --subsystem-match=net --action=add
  /sys/devices/pci0000:00/0000:00:04.0/virtio1/net/interface1
  /sys/devices/pci0000:00/0000:00:05.0/virtio2/net/interface2
    ys/devices/pci0000:00/0000:00:06.0/virtio3/net/interface0
  /sys/devices/virtual/net/lo

  root at ubuntu:~# ifconfig interface1
  interface1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1492
          inet 10.0.2.100  netmask 255.255.255.0  broadcast 10.0.2.255
          inet6 fe80::5054:ff:fe12:3402  prefixlen 64  scopeid 0x20<link>
          inet6 fec0::5054:ff:fe12:3402  prefixlen 64  scopeid 0x40<site>
          ether 52:54:00:12:34:02  txqueuelen 1000  (Ethernet)
          RX packets 16  bytes 5053 (5.0 KB)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 37  bytes 3504 (3.5 KB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

  ProblemType: Bug
  DistroRelease: Ubuntu 17.04
  Package: udev 232-18ubuntu1
  ProcVersionSignature: Ubuntu 4.10.0-8.10-generic 4.10.0-rc8
  Uname: Linux 4.10.0-8-generic x86_64
  ApportVersion: 2.20.4-0ubuntu2
  Architecture: amd64
  Date: Thu Mar  2 19:22:14 2017
  Lsusb: Error: command ['lsusb'] failed with exit code 1:
  MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
  ProcEnviron:
   TERM=vt220
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.10.0-8-generic root=UUID=8bbb84fe-91e8-4a9a-bd91-f6af4793727e ro console=ttyS0
  SourcePackage: systemd
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 04/01/2014
  dmi.bios.vendor: SeaBIOS
  dmi.bios.version: 1.10.1-1ubuntu1
  dmi.chassis.type: 1
  dmi.chassis.vendor: QEMU
  dmi.chassis.version: pc-i440fx-zesty
  dmi.modalias: dmi:bvnSeaBIOS:bvr1.10.1-1ubuntu1:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-zesty:cvnQEMU:ct1:cvrpc-i440fx-zesty:
  dmi.product.name: Standard PC (i440FX + PIIX, 1996)
  dmi.product.version: pc-i440fx-zesty
  dmi.sys.vendor: QEMU

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