[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
Tracked in Github Issues as https://github.com/canonical/cloud-
init/issues/3793
** Bug watch added: github.com/canonical/cloud-init/issues #3793
https://github.com/canonical/cloud-init/issues/3793
** Changed in: cloud-init
Status: Incomplete => Expired
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https://bugs.launchpad.net/bugs/1899487
Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
Expired
Status in neutron:
New
Status in netplan.io package in Ubuntu:
Expired
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
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[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
While Nova indeed exposes the MTU in our metadata, our source of truth
for that information is Neutron, via the `mtu` field on the Neutron
network.
[As an aside, we've had a long standing issue wherein Neutron allows the
MTU to be mutable, but there's no real support for changing the MTU
within Nova, necessitating the cold migration work around that Frode has
mentioned]
As Neutron controls both the DHCP agent and the `network` API-level
resource, I'm not sure how we'd ever get into a situation where DHCP
provides an MTU value that's different from what's set in the `network`,
but maybe there's a bug in Neutron?
So since Nova's metadata is just a proxy for Neutron's MTU in this case,
I think Brett's question in comment #21 is better asked to the Neutron
folks.
** Project changed: nova => neutron
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Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
Incomplete
Status in neutron:
New
Status in netplan.io package in Ubuntu:
Expired
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
To manage notifications about this bug go to:
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[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
Adding upstream OpenStack Nova to the bug to get their perspective on
why the OpenStack datasource is exposing MTU when it knows that the
network should be configured using DHCP ref Brett's question in #21.
** Also affects: nova
Importance: Undecided
Status: New
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Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
New
Status in OpenStack Compute (nova):
New
Status in netplan.io package in Ubuntu:
Expired
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-init/+bug/1899487/+subscriptions
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[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
I'm going to re-open this bug after working through Openstack networking
migration for OVS to OVN.
I ran into an issue where the MTU set in netplan caused all my instances
to be lost after the migration. While this can, and should, be
documented, I also think that reducing places where instances could be
lost should be taken whenever possible.
** Changed in: cloud-init
Status: Expired => New
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Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
New
Status in netplan.io package in Ubuntu:
Expired
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-init/+bug/1899487/+subscriptions
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[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
[Expired for netplan.io (Ubuntu) because there has been no activity for
60 days.]
** Changed in: netplan.io (Ubuntu)
Status: Incomplete => Expired
--
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https://bugs.launchpad.net/bugs/1899487
Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
Expired
Status in netplan.io package in Ubuntu:
Expired
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-init/+bug/1899487/+subscriptions
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[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
[Expired for cloud-init because there has been no activity for 60 days.]
** Changed in: cloud-init
Status: Incomplete => Expired
--
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https://bugs.launchpad.net/bugs/1899487
Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
Expired
Status in netplan.io package in Ubuntu:
Expired
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-init/+bug/1899487/+subscriptions
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[Yahoo-eng-team] [Bug 1899487] Re: cloud-init hard codes MTU configuration at initial deploy time
" # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}"
How is cloud-init to know from this network-config.json that DHCP will
provide an MTU value? How does it know that it should ignore the
provided MTU? If DHCP is providing MTU, should network-config.json then
not provide the MTU value?
** Also affects: netplan.io (Ubuntu)
Importance: Undecided
Status: New
** Changed in: cloud-init
Status: New => Incomplete
** Changed in: netplan.io (Ubuntu)
Status: New => Incomplete
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Title:
cloud-init hard codes MTU configuration at initial deploy time
Status in cloud-init:
Incomplete
Status in netplan.io package in Ubuntu:
Incomplete
Bug description:
When using OpenStack cloud provider `cloud-init` will write out
/etc/netplan/50-cloud-init.yaml at initial instance boot and not
update it on subsequent boots of the instance.
The OpenStack metadata service provides information about MTU for the
network [0] and cloud-init takes this value and writes it into the
netplan configuration [1].
A side effect of configuring the MTU through netplan is that the
`systemd-networkd` [Link] section [2] gets the MTUBytes value filled
and this in turn makes `systemd-networkd` ignore the MTU value
provided by DHCP [3][4].
During the lifetime of a cloud events occur that will force a operator
to reduce the MTU available to instances attached to its overlay
networks. This may happen because of software imposed change of tunnel
type (GRE -> VXLAN, VXLAN -> GENEVE) or change of topology or
encapsulation in the physical network equipment.
To maximize performance these clouds have configured their instances
to use the maximum available MTU without leaving any headroom to
account for such changes and the only way to move forward is to reduce
the available MTU on the instances. We are facing a concrete challenge
with this now where we have users wanting to migrate from VXLAN
tunnels to GENEVE tunnels with 38 byte header size.
0: # curl http://169.254.169.254/openstack/2018-08-27/network_data.json
{"links": [{"id": "tapa035fb68-01", "vif_id":
"a035fb68-010c-42e3-8da7-ea3c36a0d607", "type": "ovs", "mtu": 8942,
"ethernet_mac_address": "fa:16:3e:31:26:f7"}], "networks": [{"id": "network0",
"type": "ipv4_dhcp", "link": "tapa035fb68-01", "network_id":
"b4ef84c0-1235-48a8-aaf7-03fab7ef5367"}], "services": []}
1: # cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by the datasource. Changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
version: 2
ethernets:
ens2:
dhcp4: true
match:
macaddress: fa:16:3e:31:26:f7
mtu: 8950
set-name: ens2
2: # cat /run/systemd/network/10-netplan-ens2.link
[Match]
MACAddress=fa:16:3e:31:26:f7
[Link]
Name=ens2
WakeOnLan=off
MTUBytes=8950
3: # cat /run/systemd/network/10-netplan-ens2.network
[Match]
MACAddress=fa:16:3e:31:26:f7
Name=ens2
[Link]
MTUBytes=8950
[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6
[DHCP]
RouteMetric=100
UseMTU=true
4: Oct 12 13:30:18 canary-3 systemd-networkd[24084]:
/run/systemd/network/10-netplan-ens2.network: MTUBytes= in [Link]
section and UseMTU= in [DHCP] section are set. Disabling UseMTU=.
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https://bugs.launchpad.net/cloud-init/+bug/1899487/+subscriptions
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