I've added the ubuntu-fan package, as fanctl should accommodate the underlay MTU.
There is a work-around for the Juju case, which I will look to implement. ** Also affects: ubuntu-fan (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to ubuntu-fan in Ubuntu. https://bugs.launchpad.net/bugs/1936842 Title: agent cannot be up on LXD/Fan network on OpenStack OVN/geneve mtu=1442 Status in juju: Triaged Status in ubuntu-fan package in Ubuntu: New Bug description: When one runs OpenStack with MTU=1500 underlying network, Neutron/OVN by default will create a tenant/overlay network with MTU=1442(1500-58). However, when deploying a workload on top, the Fan network with Juju will use MTU=1450 which is actually bigger than that. Then, Juju agent cannot be up inside LXD/Fan on top of OpenStack. OpenStack deployment is based on https://jaas.ai/openstack-base and k8s as a workload on top of OpenStack is: https://jaas.ai/kubernetes-core $ openstack network list +--------------------------------------+----------+--------------------------------------+ | ID | Name | Subnets | +--------------------------------------+----------+--------------------------------------+ | ba9880e3-5f07-4b49-aeda-20dfa8fe66ec | internal | 45efcc4c-fb99-4fe8-98a4-77195ec4aef1 | | e27b1cef-c53b-42e0-b307-8ba2e622c2dd | ext_net | 5315d907-ce90-4605-ad72-b78229965b40 | +--------------------------------------+----------+--------------------------------------+ $ openstack network show internal +---------------------------+--------------------------------------+ | Field | Value | +---------------------------+--------------------------------------+ ... | mtu | 1442 | | name | internal | ... | provider:network_type | geneve | | provider:physical_network | None | | provider:segmentation_id | 1410 | ... +---------------------------+--------------------------------------+ $ juju machines -m k8s-on-openstack Machine State DNS Inst id Series AZ Message 0 started 192.168.151.75 0e96a5b1-3665-44f6-bcb7-4851ab6cd22d focal nova ACTIVE 0/lxd/0 pending juju-b9bd8b-0-lxd-0 focal nova Container started 1 started 192.168.151.66 6bfa5d2e-24e6-42b8-b5ec-1f2a0d0e6b02 focal nova ACTIVE [openstack instance/VM provisioned by Juju - ens3: mtu=1442, fan-252: mtu=1450] juju-b9bd8b-k8s-on-openstack-0:~# ip link 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 1442 qdisc fq_codel state UP mode DEFAULT group default qlen 1000 link/ether fa:16:3e:48:85:85 brd ff:ff:ff:ff:ff:ff 3: fan-252: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether 06:28:c7:b4:50:eb brd ff:ff:ff:ff:ff:ff 4: ftun0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1392 qdisc noqueue master fan-252 state UNKNOWN mode DEFAULT group default qlen 1000 link/ether 92:d7:07:6e:b4:db brd ff:ff:ff:ff:ff:ff 5: lxdbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000 link/ether 00:16:3e:03:0e:96 brd ff:ff:ff:ff:ff:ff 7: 0lxd0-0@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue master fan-252 state UP mode DEFAULT group default qlen 1000 link/ether 06:28:c7:b4:50:eb brd ff:ff:ff:ff:ff:ff link-netnsid 0 [lxc config of LXD container as juju machine 0/lxd/0] juju-b9bd8b-k8s-on-openstack-0:~# lxc config show juju-b9bd8b-0-lxd-0 ... user.user-data: | #cloud-config apt_mirror: "" bootcmd: - install -D -m 644 /dev/null '/etc/netplan/99-juju.yaml' - |- printf '%s\n' 'network: version: 2 ethernets: eth0: match: macaddress: 00:16:3e:82:f9:44 dhcp4: true nameservers: search: [openstack.internal] addresses: [8.8.8.8, 8.8.4.4] mtu: 1450 ... devices: eth0: host_name: 0lxd0-0 hwaddr: 00:16:3e:82:f9:44 mtu: "1450" name: eth0 nictype: bridged parent: fan-252 type: nic [cloud-init-output.log - stuck at the initial apt update and also failing to fetch the agent binary] Cloud-init v. 21.2-3-g899bfaa9-0ubuntu2~20.04.1 running 'modules:config' at Mon, 19 Jul 2021 03:27:32 +0000. Up 53.99 seconds. Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease Err:2 http://security.ubuntu.com/ubuntu focal-security InRelease Connection failed [IP: 192.168.151.1 8000] Err:3 http://archive.ubuntu.com/ubuntu focal-updates InRelease Connection failed [IP: 192.168.151.1 8000] Err:4 http://archive.ubuntu.com/ubuntu focal-backports InRelease Connection failed [IP: 192.168.151.1 8000] Ign:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages Ign:6 http://archive.ubuntu.com/ubuntu focal/universe Translation-en Ign:7 http://archive.ubuntu.com/ubuntu focal/universe amd64 c-n-f Metadata Ign:8 http://archive.ubuntu.com/ubuntu focal/multiverse amd64 Packages Ign:9 http://archive.ubuntu.com/ubuntu focal/multiverse Translation-en Ign:10 http://archive.ubuntu.com/ubuntu focal/multiverse amd64 c-n-f Metadata Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB] Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB] Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB] Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB] Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB] Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB] + printf Attempt 5 to download agent binaries from %s...\n https://192.168.151.101:17070/model/9e5ed9b4-224d-4486-8dac-b56a70b9bd8b/tools/2.9.8-ubuntu-amd64 Attempt 5 to download agent binaries from https://192.168.151.101:17070/model/9e5ed9b4-224d-4486-8dac-b56a70b9bd8b/tools/2.9.8-ubuntu-amd64... + curl -sSfw agent binaries from %{url_effective} downloaded: HTTP %{http_code}; time %{time_total}s; size %{size_download} bytes; speed %{speed_download} bytes/s --connect-timeout 20 --noproxy * --insecure -o /var/lib/juju/tools/2.9.8-ubuntu-amd64/tools.tar.gz https://192.168.151.101:17070/model/9e5ed9b4-224d-4486-8dac-b56a70b9bd8b/tools/2.9.8-ubuntu-amd64 curl: (28) Operation timed out after 20000 milliseconds with 0 out of 0 bytes received agent binaries from https://192.168.151.101:17070/model/9e5ed9b4-224d-4486-8dac-b56a70b9bd8b/tools/2.9.8-ubuntu-amd64 downloaded: HTTP 000; time 20.000946s; size 0 bytes; speed 0.000 bytes/s + echo Download failed, retrying in 15s Download failed, retrying in 15s + sleep 15 [manually run tracepath to get pmtu] juju-b9bd8b-0-lxd-0:~# tracepath -n -m 5 192.168.151.1 1?: [LOCALHOST] pmtu 1450 1: 252.16.0.1 0.346ms 1: 252.16.0.1 0.051ms 2: 252.16.0.1 0.053ms pmtu 1442 2: no reply 3: 192.168.151.1 3.283ms reached Resume: pmtu 1442 hops 3 back 3 To manage notifications about this bug go to: https://bugs.launchpad.net/juju/+bug/1936842/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp