Ubuntu 18.04 LTS - ltsp clients lost network connection after tftp boot and network service start

[Jan Hubený]

Hi,

we are using ltsp environment in Ubuntu 18.04 LTS. Something goes wrong with last package updates. I have fully updated the system and the client images on September 22nd. The LTSP environment worked and everything was fine. I made another full system update on October 13rd. The update includes:

on ltsp server:
apt update
apt upgrade
reboot

on client images:
ltsp-chroot -a amd64 /bin/bash
apt update
apt upgrade
exit

on ltsp server:
ltsp-update-image amd64

after this procedure the ltsp clients boot never more. The tftp boot works, but when the client mounts the squashfs system and runs the systemd job Network service, the boot hangs. Until the network service start, the ltsp thin client reply on ping, after Network service starts the ping stops.

I tested this behaviour on two indepent ltsp instalations. The behaviour is the same on both sites. THere is no difference between thin or fat client config.
When I turned to last working image with

ltsp-update-image -r amd64

then the clients started to boot again. Therefore I suppose, that some update between September 22nd and October 13rd broke the Network service in ltsp client.

[Alkis Georgopoulos (alkisg)]

Hi, what is the output of the following command?
sudo ltsp-info

[Jan Hubený (hubeny)]

reply to Alkis Georgopoulos comment #1
ltsp-info
server information:
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Codename: bionic

server packages:
ii ldm 2:2.2.19-1
un ldm-server <none>
ii ltsp-client 5.5.10-1build1
ii ltsp-client-core 5.5.10-1build1
un ltsp-docs <none>
ii ltsp-server 5.5.10-1build1
un ltsp-utils <none>
un ltspfs <none>
ii ltspfsd 1.5-1
ii ltspfsd-core 1.5-1

packages in chroot: /opt/ltsp/amd64
ii ldm 2:2.2.19-1
un ldm-themes <none>
ii ldm-ubuntu-theme 2:2.0.47
un ldm-ubuntu-themes <none>
ii ltsp-client 5.5.10-1build1
ii ltsp-client-core 5.5.10-1build1
ii ltspfsd 1.5-1
ii ltspfsd-core 1.5-1

found: /opt/ltsp/amd64/etc/lts.conf

found: /var/lib/tftpboot/ltsp/amd64/lts.conf

found image: /opt/ltsp/images/amd64.img

[Alkis Georgopoulos (alkisg)]

You're using the stock Ubuntu LTSP version.
A systemd or network-manager update probably broke it.
I don't think it's a bug in systemd or network-manager; but that update triggered a bug in LTSP that wasn't triggered previously.

I don't know of anyone maintaining the stock Ubuntu LTSP version.

I'm an LTSP developer and I maintain newer versions of LTSP for Ubuntu in this PPA:
https://launchpad.net/~ts.sch.gr/+archive/ubuntu/ppa

If you add that PPA in your sources, both in the server and the chroot, and fully update, the problem you saw will probably go away.

I do mention adding the PPA in the recommended LTSP installation instructions:
http://wiki.ltsp.org/wiki/Installation/Ubuntu

If someone wants to backport a newer LTSP version into stock Ubuntu repositories, he should follow the documentation at https://wiki.ubuntu.com/UbuntuBackports.
Due to lack of time I'm not going to do it, but I'm willing to help anyone that is interested in continuously backporting newer LTSP versions into LTS Ubuntu versions.

[Jan Hubený (hubeny)]

I have just tested your recommendation and I confirm that the problem goes away...
Thank you for a quick response. Have a nice day.

[Alkis Georgopoulos (alkisg)]

Thanks for the feedback, I'm marking this as fix released since it's working fine in the latest LTSP version.

And noting again that if someone wants to get it in Ubuntu backports without using a PPA, he should follow the steps of https://wiki.ubuntu.com/UbuntuBackports.