No thumbnails of fat client

I'm converting the bug report into a question, as it's not a bug in the application but a user error.

The problem is that the /etc/epoptes/server.crt file is empty, of size zero.
That might have happened if you ran `sudo epoptes-client -c localhost` on the server instead of some chroot.
You don't need to run `epoptes-client -c` at all, in ltsp-pnp.

EITHER see: http://www.epoptes.org/installation#TOC-Manually-updating-the-OpenSSL-certificate for how to create a new certificate.
OR run: sudo apt-get purge epoptes; sudo apt-get install epoptes
(don't do both of them)

Then run `sudo ltsp-update-image -c /`, then reboot the clients.

I run
1. sudo apt-get purge epoptes
2. sudo apt-get install epoptes
3. sudo ltsp-update-image -c /

and no effect

I run
1. openssl req -batch -x509 -nodes -newkey rsa:1024 -days 1826 -keyout /etc/epoptes/server.key -out /etc/epoptes/server.crt
2. sudo ltsp-update-image -c /
sudo
and no effect

On server
md5sum /etc/epoptes/*

c0c13a7d5c70fc5ff49ddeff7d87c827 /etc/epoptes/server.crt
db7701408d7181b5d2c6f20d374404c9 /etc/epoptes/server.key

On client
md5sum /etc/epoptes/*
c0c13a7d5c70fc5ff49ddeff7d87c827 /etc/epoptes/server.crt

The certificates seem ok now,
from a client, try:
epoptes-client

Does it connect to the server? I.e. does it say "Done" at the end?

And, what's the output of the `date` command on the fat client?

On fat client as a user:
epoptes-client

in terminal:
Command 'epoptes-client' is available in '/usr/sbin/epoptes-client'
The command could not be located because '/usr/sbin' is not included in the PATH environment variable.
This is most likely caused by the lack of administrative privileges associated with your user account.
epoptes-client: command not found

Yeah since you're not a sudoer, you don't have /usr/sbin/ in your path, so run:
/usr/sbin/epoptes-client

Ah.. Well yes
In terminal:
* Epoptes-client connecting to server:789...
...done.

After the command I see preview:)
Is it possible to somehow fix it?

It seems that epoptes-client is not starting automatically in the user session due to a lxsession bug (Lubuntu specific): https://bugs.launchpad.net/ubuntu/+source/lxsession/+bug/1309698

Until it's fixed you could create an upstart job as a workaround:
Create a file /usr/share/upstart/sessions/epoptes-client.conf with the following contents:
description "Epoptes client service (upstart)"

start on desktop-start

exec /usr/sbin/epoptes-client

After you save it, run:
sudo ltsp-update-image -c /

and you should be able to see client thumbnails.

I create file /usr/share/upstart/session/epoptes-client.conf
 with content:

description "Epoptes client service (upstart)"

start on desktop-start

exec /usr/sbin/epoptes-client

and it does not work for me :(

The path you mention is wrong, replace "session" with "sessions", it's an existing directory including other .conf files.

Of course, is yes. This typographical error.

Today, for one machine this entry work. Thumbnail is. But on the other is still missing. Strange.