================================================
Requirements before installing Lizmap Web Client
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.. note:: If you want to quickly install and test Lizmap Web Client in a few steps, you can follow those `instructions <https://github.com/3liz/lizmap-docker-compose>`_.

QGIS Server
===========

.. warning::
    Before installing the QGIS Server part, it is **very highly** recommended to use the **same** version
    between QGIS Desktop and QGIS Server.

    Even if some functions might work, there is a probability that some configuration won't work if these two
    versions are **different**.

    The reason is QGIS Server version X might not be able to a QGIS project made with a QGIS Desktop version Y.

Follow the QGIS Documentation how to install QGIS Server : https://docs.qgis.org/latest/en/docs/server_manual/

Using a webserver (Apache or Nginx), you must install QGIS Server. With Nginx, the preferred way is to use
``spawn-fcgi``. Do **not** use the ``fcgiwrap``, this solution is not efficient.

In the Nginx configuration, it's good to use the ``QGIS_OPTIONS_PATH`` variable for a folder with write
permissions for ``www-data``. These is explained in the QGIS Server documentation.

You should also install and configure ``XVFB`` mentioned in the QGIS Documentation.
This is useful for printing PDF. You can only skip this section if you don't plan to print PDF on the server
side.

After you have setup your web server with QGIS-Server, check that the URL of QGIS Server is working. You
probably get a XML like:

.. code-block:: xml

    <ServerException>Project file error</ServerException>

Keep this URL, we will use it later in the Lizmap admin panel.

.. warning::
    We **strongly** encourage you to set up QGIS Server on a different virtual host than Lizmap Web Client.
    QGIS Server URL should stay private, accessible by the Lizmap PHP application **only**.

    Otherwise, especially after the **Lizmap** plugin on QGIS Server is installed, your user might be able to
    access private data if they by-pass Lizmap, by using straight QGIS Server URL.

QGIS Server plugins
-------------------

Some plugins can be added to QGIS Server. This will enable some features in Lizmap. It's not compulsory but
in some situations, it's better.

Either you should setup the ``QGIS_PLUGIN_PATH`` environment variable during the installation of QGIS Server
or use the default one provided by QGIS.
https://docs.qgis.org/latest/en/docs/server_manual/config.html#environment-variables

.. tip::
    To manage QGIS Server plugins, we encourage you to use **qgis-plugin-manager**, a CLI tool to install and
    upgrade plugins. https://pypi.org/project/qgis-plugin-manager/

* AtlasPrint

    * To enable the PDF based on a QGIS Layout Atlas
    * https://github.com/3liz/qgis-atlasprint

* Cadastre

    * French use-case only
    * Needed for the Lizmap Cadastre module
    * https://docs.3liz.org/QgisCadastrePlugin/module-lizmap/

* Lizmap

    * Lizmap **is not only** a PHP application, there is also Python plugin for **QGIS Server** to

        * evaluate `QGIS Expressions <https://docs.qgis.org/testing/en/docs/user_manual/working_with_vector/expression.html>`_
          in forms about :

           * constraints
           * default value
           * group visibility
           * Read :ref:`edition-expressions`.

        * check User Access Rights (ACL) for features and layers :

           * filter by polygon
           * by attribute

        * enable ``@lizmap_user`` and ``lizmap_user_groups`` variables
    * https://github.com/3liz/qgis-lizmap-server-plugin
    * The plugin is not required, but a few features won't work as expected if the plugin is not installed or not upgraded
    * The name of the plugin is **Lizmap server**. Do not install the **Lizmap** plugin which is the **desktop** Python plugin.

* WfsOutputExtension

    * To add new format when exporting vector data
    * https://github.com/3liz/qgis-wfsOutputExtension

* Logging

    * To log QGIS Servers log and to flush the cache on QGIS Server
    * https://github.com/3liz/qgis-logging-plugin.
    * This plugin is deprecated.

PostgreSQL
----------

PostgreSQL can be used for two different purposes in Lizmap :

* To store GIS data. No configuration is needed on the Lizmap Web Client server side, **only** the PostgreSQL server
  must be accessible from the Lizmap Web Client server.
  It's possible to edit layers with Lizmap, but the layer **must** be stored in PostgreSQL. See :ref:`edition-prerequisites`.
* To store Lizmap Web Client users and user actions. Lizmap uses tables. This setting must be done when **installing** Lizmap.