networkd does not accept / set advertised mtu

[Dimitri John Ledkov]

[Impact]
Hosts may require a specific MTU to be set as passed by DHCP options. We should honor these settings to ensure proper communication of the host with the rest of the network.

[Test case]
1) Run netplan on a system that should receive MTU settings from DHCP.
2) Validate that the MTU configuration provided by DHCP is applied to the right interface.

[Regression Potential]
If DHCP settings specify an invalid MTU setting which is currently being ignored and letting the systems communicate correctly with the network, then these systems would regress.

---

<wgrant> Right, so as far as I can tell the neutron-api on lcy01 is configured to advertise an instance interface MTU of 1400, though that's lower than it has to be, and the new DHCP setup with networkd just doesn't respect that DHCP option.

[Dimitri John Ledkov (xnox)]

<wgrant> netplan needs to set DHCP.UseMTU=yes
<wgrant> If I do that, my local instance no longer behaves strangely, and the MTU is correctly 1458

[Dimitri John Ledkov (xnox)]

xnox> wgrant, t0mb0, veebers - i think i will just change ubuntu compiled in default for systemd-networkd to be honest.
<wgrant> xnox: That sounds perilous.
<xnox> wgrant, had to google that word.
<xnox> wgrant, alternatives is to bake that into nplan, or bake that into the cloud-image alone
<wgrant> xnox: nplan makes the most sense, IMO, rather than changing a confusing non-configurable upstream default silently in a distro patch.
<xnox> wgrant, i did that to accept search domains in resolved =/ because there is no easy way to set defaults for that, as it needs to go into the network file, and systemd only considers the first matching network file and ignores the rest (or some such)
<wgrant> Er yeah, I meant .network in the ticket when I said .link. The .link is fine.
<wgrant> systemd is so lovely.

[Dimitri John Ledkov (xnox)]

Upstream pull request https://github.com/systemd/systemd/pull/6837

[Launchpad Janitor (janitor)]

This bug was fixed in the package nplan - 0.27

---------------
nplan (0.27) artful; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * Fix crash in systemd generator if called by an user on the command-line
  * coverage: fix exclusions to properly not cover our "never reached defaults"

  [ Dimitri John Ledkov ]
  * tests/integration.py: In teardown, stop systemd-networkd.socket.
  * src/networkd.c: Set UseMTU=true by default, whenever DHCP is in use.
    (LP: #1717471)
  * tests/integration.py: fix resolved detection.

 -- Dimitri John Ledkov <email address hidden> Fri, 15 Sep 2017 14:25:22 +0100

[Brian Murray (brian-murray)]

Hello Dimitri, or anyone else affected,

Accepted nplan into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.29~17.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Brian Murray (brian-murray)]

Hello Dimitri, or anyone else affected,

Accepted nplan into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.29~16.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Launchpad Janitor (janitor)]

This bug was fixed in the package systemd - 234-2ubuntu12

---------------
systemd (234-2ubuntu12) artful; urgency=medium

  [ Dimitri John Ledkov ]
  * debian/rules: do not strip test-copy.
    This insures test-copy is large enough for test-copy tests to pass.
    (LP: #1721203)

  [ Michael Biebl ]
  * Drop systemd-timesyncd.service.d/disable-with-time-daemon.conf.
    All major NTP implementations ship a native service file nowadays with a
    Conflicts=systemd-timesyncd.service so this drop-in is no longer
    necessary. (Closes: #873185) (LP: #1721204)

 -- Dimitri John Ledkov <email address hidden> Wed, 04 Oct 2017 13:28:34 +0100

[Mathieu Trudel-Lapierre (cyphermox)]

Verification-done for xenial with nplan 0.29~16.04.1:

This was a regression in the development release that transpired in a new SRU that has not been migrated to the stable release. The bad version is 0.26; current state of nplan in xenial is 0.23~16.04.1 in -updates.

Verified that lxc list shows an IPv4 and IPv6 address when a container is set up to use netplan with 0.29~16.04.1.

[Mathieu Trudel-Lapierre (cyphermox)]

Verification-done for zesty with nplan 0.29~17.04.1:

I verified that the generated networkd config in the .network file contains "UseMTP=true" in the [DHCP] section; and the container gets the right MTU from the DHCP server.

[Łukasz Zemczak (sil2100)]

Hello Dimitri, or anyone else affected,

Accepted nplan into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.32~17.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Łukasz Zemczak (sil2100)]

Hello Dimitri, or anyone else affected,

Accepted nplan into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.32~16.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Mathieu Trudel-Lapierre (cyphermox)]

nplan 0.32~16.04.2 fails to build because I mismerged 0.32 and broke the code skipping the test_routes_v6 test in the NetworkManager case. Therefore, it can't possibly pass SRU verification.

[Brian Murray (brian-murray)]

Hello Dimitri, or anyone else affected,

Accepted nplan into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.32~16.04.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Mathieu Trudel-Lapierre (cyphermox)]

Autopktests still failing for xenial; the test is still not being skipped (we know it won't work on Xenial due to the version of NM shipped there). Marking verification-failed-xenial.

[Łukasz Zemczak (sil2100)]

Hello Dimitri, or anyone else affected,

Accepted nplan into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nplan/0.32~16.04.3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Mathieu Trudel-Lapierre (cyphermox)]

Verification-done for xenial 0.32~16.04.3, and zesty 0.32~17.04.1:

UseMTU=yes is set on the interfaces for which a MTU is set, and the MTU coming from DHCP is applied correctly when running 'netplan apply'.

[Launchpad Janitor (janitor)]

This bug was fixed in the package nplan - 0.32~16.04.3

---------------
nplan (0.32~16.04.3) xenial; urgency=medium

  * tests/integration.py: Really fix skipping test_routes_v6 for the NM
    backend.

nplan (0.32~16.04.2) xenial; urgency=medium

  * tests/integration.py: Fix test_routes_v6 that I clobbered when I re-applied
    the skip rules for 16.04 after merging in 0.32.

nplan (0.32~16.04.1) xenial; urgency=medium

  * Backport netplan 0.32 to 16.04. (LP: #1713142)
  * debian/control: Depend on systemd (>= 229-4ubuntu20) for the PrimarySlave
    feature backported in that revision.
  * tests/integration.py: Skip tests that are still not yet supported in xenial

nplan (0.32) bionic; urgency=medium

  * src/nm.c: better handle the UUID generation; the order of iterating
    through interaces may affect things here. Also make sure the tests catch
    a null UUID.

nplan (0.31) bionic; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * src/nm.c: generate a UUID for a connection only as needed; when we're
    dealing with NM VLANs. (LP: #1712921)
  * debian/tests/autostart: Make the autostart test more verbose and avoid
    failing right from the start when systemd-networkd is disabled.
    (LP: #1699371)
  * tests/integration.py: bump the NetworkManager timeout for settling to
    120 seconds, autopkgtest infrastructure tends to be a little slow for the
    network device configuration to be applied and noticed by NM.
    (LP: #1699371)

  [ Dimitri John Ledkov ]
  * Reload udevd to invalidate configuration cache of .rules/.link files
    as generate step may have changed them. LP: #1669564

  [ Dan Streetman ]
  * Add another interface driver exception to netplan replug to prevent unbind
    of the Xen VIF interfaces. (LP: #1729573)

nplan (0.30) artful; urgency=medium

  * Add an "optional" syntax node for now to all devices. This is unimplemented
    for now, but intended to allow users to mark some devices as optional: to
    make sure they do not delay boot when configured. (LP: #1664844)

nplan (0.29) artful; urgency=medium

  * Fix autopkgtests in a world where /run/NetworkManager/conf.d already
    exists. nplan is enabled by default, so it might well have the directory
    already created on the filesystem.

nplan (0.28) artful; urgency=medium

  * Revert 56cd3eec which disabled IPv6 Router Advertisements by default. It
    broke default network config in LXD and was contrary to the defaults used
    by the kernel. Reopens LP: 1655440. (LP: #1717404)
  * Add "accept-ra:" key for all device types; this will default to OFF but
    allow users to disable processing Router Advertisements when required by
    their network setup. (LP: #1655440)

nplan (0.27) artful; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * Fix crash in systemd generator if called by an user on the command-line
  * coverage: fix exclusions to properly not cover our "never reached defaults"

  [ Dimitri John Ledkov ]
  * tests/integration.py: In teardown, stop systemd-networkd.socket.
  * src/networkd.c: Set UseMTU=true by default, whenever DHCP is in use.
    (LP: #1717471)
  * tests/integration.py: fix resolved detection.

nplan (0.26) artful; urgency=medium

 ...

[Chris Halse Rogers (raof)]

The verification of the Stable Release Update for nplan has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package nplan - 0.32~17.04.1

---------------
nplan (0.32~17.04.1) zesty; urgency=medium

  * Backport 0.32 to 17.04. (LP: #1713142)

nplan (0.32) bionic; urgency=medium

  * src/nm.c: better handle the UUID generation; the order of iterating
    through interaces may affect things here. Also make sure the tests catch
    a null UUID.

nplan (0.31) bionic; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * src/nm.c: generate a UUID for a connection only as needed; when we're
    dealing with NM VLANs. (LP: #1712921)
  * debian/tests/autostart: Make the autostart test more verbose and avoid
    failing right from the start when systemd-networkd is disabled.
    (LP: #1699371)
  * tests/integration.py: bump the NetworkManager timeout for settling to
    120 seconds, autopkgtest infrastructure tends to be a little slow for the
    network device configuration to be applied and noticed by NM.
    (LP: #1699371)

  [ Dimitri John Ledkov ]
  * Reload udevd to invalidate configuration cache of .rules/.link files
    as generate step may have changed them. LP: #1669564

  [ Dan Streetman ]
  * Add another interface driver exception to netplan replug to prevent unbind
    of the Xen VIF interfaces. (LP: #1729573)

nplan (0.30) artful; urgency=medium

  * Add an "optional" syntax node for now to all devices. This is unimplemented
    for now, but intended to allow users to mark some devices as optional: to
    make sure they do not delay boot when configured. (LP: #1664844)

nplan (0.29) artful; urgency=medium

  * Fix autopkgtests in a world where /run/NetworkManager/conf.d already
    exists. nplan is enabled by default, so it might well have the directory
    already created on the filesystem.

nplan (0.28) artful; urgency=medium

  * Revert 56cd3eec which disabled IPv6 Router Advertisements by default. It
    broke default network config in LXD and was contrary to the defaults used
    by the kernel. Reopens LP: 1655440. (LP: #1717404)
  * Add "accept-ra:" key for all device types; this will default to OFF but
    allow users to disable processing Router Advertisements when required by
    their network setup. (LP: #1655440)

nplan (0.27) artful; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * Fix crash in systemd generator if called by an user on the command-line
  * coverage: fix exclusions to properly not cover our "never reached defaults"

  [ Dimitri John Ledkov ]
  * tests/integration.py: In teardown, stop systemd-networkd.socket.
  * src/networkd.c: Set UseMTU=true by default, whenever DHCP is in use.
    (LP: #1717471)
  * tests/integration.py: fix resolved detection.

nplan (0.26) artful; urgency=medium

  * Bonding:
    - Add support for specifying a primary slave. (LP: #1709135)
  * Rebind:
    - Fix brcmfmac harder. Treat any 'brcmfmac' driver as not supporting
      rebind. (LP: #1712224)
  * Autopkgtests:
    - Add allow-stderr. Systemd now bleats about a the networkd socket still
      being around and enabled when we restart the service; but we don't need
      to care since we're /restarting/ the service to load the new config.
    - Fix the autostart package to be more sensible: we don't really care if
 ...

[Brian Murray (brian-murray)]

Hello Dimitri, or anyone else affected,

Accepted systemd into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/systemd/229-4ubuntu21.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Dimitri John Ledkov (xnox)]

Configured lxd bridge network with 'raw.dnsmasq' option specifying MTU to be 1493.
Started xenial container, and set it to use networkd, with DHCPv4, without specifying UseMTU= setting.
With systemd 229-4ubuntu21.1, the container dhcp's and `ip a` output states that MTU is 1500.
Upgrading to 229-4ubuntu21.2, and rebooting the container results in `ip a` output to state that MTU is 1492.

[Launchpad Janitor (janitor)]

This bug was fixed in the package systemd - 229-4ubuntu21.2

---------------
systemd (229-4ubuntu21.2) xenial; urgency=medium

  [ Dimitri John Ledkov ]
  * udev: Mark ndb devices as inactive until connected. (LP: #696435)
  * networkd: in dhcp, change UseMTU default to true, to accept DHCP provided MTU by default.
    (LP: #1717471)
  * sysctl: apply parameters in-order, instead of randomly. (LP: #1718444)
  * networkd: apply promote_secondaries, to make DHCP lease changes work.
    (LP: #1721223)
  * shutdown: sync filesystems, before going into a killing spree.
    (LP: #1722481)
  * sysctl: do not fail, when cannot apply sysctl changes due to read-only sysfs in containers.
    (LP: #1734409)
  * networkd,wait-online: add RequiredForOnline to mark mandatory/optional links for boot.
    (LP: #1737570)

  [ David Glasser ]
  * journald: don't reduce BurstRateLimit on low disk space (LP: #1732803)

 -- Dimitri John Ledkov <email address hidden> Wed, 21 Feb 2018 13:46:37 +0000