Simpler method for fat/thin client setups

[Alkis Georgopoulos]

Now that the ltsp-server and ltsp-client packages are allowed to be 
installed simultaneously (LP: #950945), I thought of an extremely simple 
method to install and maintain LTSP fat/thin computer labs that should 
be appealing to certain setups like small school labs.
We'll probably start using it in Greek schools in a month, and I'd like 
to ask the community for feedback on where this could lead to problems, 
and also on whether there's interest in an internationalized version of 
the "ltsp-server-pnp" package that we'll develop to automate this.

The installation steps for this new method will be:
  1. Install your server normally with any DE you prefer (Gnome, KDE, 
XFCE, LXDE...). Also install and configure on the server any 
applications that you want to have in your thin/fat clients.
  2. Add the repository for the yet-to-be-developed ltsp-server-pnp 
package, which automatically installs and configures ltsp-server, 
ltsp-client, dnsmasq, PXE menus etc for you.
  3. Reboot your server and select "Recovery console" in the grub menu. 
 From the recovery menu that will appear, select "Generate LTSP image". 
This will create the /opt/ltsp/images/i386.img NBD image, and it will 
need about 5-10 minutes to complete, without requiring Internet 
connectivity.

  That's all, you can then boot your server normally and start your 
thin/fat clients. If you need to "update your chroot" in the future, you 
just do any changes you want directly on the server (add/remove apps or 
settings) and follow step (3) again.

  Pros:
   * Great simplicity. As you've seen, there's *no LTSP chroot 
involved*, so no "ltsp-build-client" step, no "ltsp-chroot install 
packages" step, no "manually transfer gconf mandatory settings to the 
chroot" step.

  Cons:
   * Loss of flexibility. The server needs to be the same arch as the 
clients, so you'll probably want the i386-pae kernel in your server. You 
can't even have different packages installed in your server than in your 
thin/fat clients. But you can still have e.g. apache, mysql, sshd etc 
installed on your server and put them in the RM_SYSTEM_SERVICES lts.conf 
directive so that they don't run in your clients. No, that doesn't put 
any additional RAM overhead, your clients can still have as low as 128 
MB RAM no matter how many services you have installed on your server. 
And of course in bigger setups you can use a separate server for 
NFS/apache/whatever, and only keep the LTSP-related services in the 
server where ltsp-server-pnp runs.
   * Security concerns. E.g. the clients will have the same sshd keys as 
your server. But I think that in step (3) above, the security-sensitive 
data can be regenerated or omitted. And of course /home, /srv, /opt, and 
user's entries in /etc/passwd and /etc/shadow will be omitted too in the 
NBD image.
   * Finally, your server needs to be rebooted to update the NBD image, 
so some downtime is involved. This will be avoided in the future when 
BTRFS snapshots will be available.

Thoughts? And, does anyone care about an internationalized Ubuntu 
Precise/Debian Wheezy package for this?