.. _printing_config_overview:

Printer Configuration Overview
------------------------------

This section provides an overview of how printing is configured in a
ThinLinc cluster.

.. figure:: images/printer_config_overview.svg

   Printer Configuration Overview

CUPS Browsing
~~~~~~~~~~~~~

It is important that the CUPS Browsing feature is **turned off** on all
machines in the cluster, or problems with duplicate **thinlocal**
printers will occur.

CUPS configuration on the Machine Running VSM Server
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Configure all printers that need to be available in the CUPS
configuration on the machine running VSM Server. Either use
distribution-specific tools, or the built-in administration interface in
CUPS which can usually be reached by using a web browser, connecting to
port 631 on the machine, i.e. http://tl.example.com:631/.

The **nearest** and **thinlocal** queues, used by the nearest printer
and the local printer features respectively, are added by ThinLinc
Setup.

Printers, with one exception (see below) only needs to be configured on
the machine running VSM Server. Agent nodes will use the CUPS daemon
(cupsd) on the VSM Server machine for printing.

CUPS configuration on the Machine running VSM Agent
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The machines in the cluster that run VSM Agent, i.e., the machines that
host user sessions, needs a running CUPS daemon (cupsd), but this cupsd
only needs one printer defined - the **thinlocal** queue. The reason for
this is that the local printer backend needs to run on the same machine
as the session of the user printing to local printer to be able to
access the endpoint of the SSH tunnel used to transport the printer job
to the client.

The **thinlocal** queue is added by ThinLinc Setup when installing the
agent.

.. note::

   The CUPS daemon on each agent must listen to requests on the network
   interface, and allow printer jobs from the machine running VSM Server
   to be submitted to the **thinlocal** queue.

When a user submits a job to the local printer, i.e. to the
**thinlocal** queue, the printer job will be submitted to the CUPS
daemon running on the VSM Server host. It will then be respooled to the
cupsd on the agent server hosting the session. This is to make central
configuration of all other printers possible.