5. Plugins

5.1. List of plugins 

Plugins can also be installed on QGIS Server.

Some plugins designed for server can be found on the official QGIS repository.

Install only plugins you need for your own purpose. On QGIS server, plugins are like hooks into QGIS server, they can alter inputs or outputs of QGIS server. They can produce unexpected result if you don’t know how the plugin works. Please refer to their respective documentation or the application that needs QGIS server plugins to know which plugin can be useful for you.

5.2. Location of plugins 

By default, on Debian based systems, QGIS Server will look for plugins located in /usr/lib/qgis/plugins. The default value is displayed when QGIS Server is starting, in the logs. It’s possible to set a custom path by defining the environment variable QGIS_PLUGINPATH in the web server configuration.

5.3. Installation 

5.3.1. Manually with a ZIP 

As an example, to install the HelloWorld plugin for testing the server, using a specific folder, you first have to create a directory to hold server plugins. This will be specified in the virtual host configuration and passed on to the server through an environment variable:

mkdir -p /var/www/qgis-server/plugins
cd /var/www/qgis-server/plugins
wget https://github.com/elpaso/qgis-helloserver/archive/master.zip
unzip master.zip
mv qgis-helloserver-master HelloServer

Warnung

According to its description, HelloServer plugin is designed for development and demonstration purposes. Do not keep this plugin for production if you don’t need it.

5.3.2. With a command line tool 

If you need to install and regularly upgrade plugins which are stored in the QGIS plugin repository, you may use the QGIS-Plugin-Manager. It’s a tool to help you manage plugins from the command line.

The installation is using pip. Installing in a virtual environment is a good practice but not required:

pip3 install qgis-plugin-manager

To upgrade the tool:

pip3 install --upgrade qgis-plugin-manager

Then, you can use the qgis-plugin-manager executable from the command line:

cd /var/www/qgis-server/plugins
qgis-plugin-manager list

QGIS server version 3.19.0
List all plugins in /var/www/qgis-server/plugins

------------------------------------------------------------------------------------------------------------------------------------------------------------
|  Folder                    |  Name              |  Version  |  Experimental  |  QGIS min  |  QGIS max  |  Author                    |  Action ⚠          |
------------------------------------------------------------------------------------------------------------------------------------------------------------
|wfsOutputExtension          |wfsOutputExtension  |1.6.2      |                |3.0         |            |3Liz                        |                    |
|qgis_server_render_geojson  |GeoJson Renderer    |v0.4       |                |3.4         |            |Matthias Kuhn (OPENGIS.ch)  |                    |
|DataPlotly                  |Data Plotly         |3.7.1      |                |3.4         |3.98        |Matteo Ghetta (Faunalia)    |Upgrade to 3.8.1    |
------------------------------------------------------------------------------------------------------------------------------------------------------------

We suggest you to read the full documentation in the readme file to know how to install or upgrade plugins with this tool.

5.4. HTTP Server configuration 

5.4.1. Apache 

To be able to use server plugins, FastCGI needs to know where to look. So, we have to modify the Apache configuration file to indicate the QGIS_PLUGINPATH environment variable to FastCGI:

FcgidInitialEnv QGIS_PLUGINPATH "/var/www/qgis-server/plugins"

Moreover, a basic HTTP authorization is necessary to play with the HelloWorld plugin previously introduced. So we have to update the Apache configuration file a last time:

# Needed for QGIS HelloServer plugin HTTP BASIC auth
<IfModule mod_fcgid.c>
    RewriteEngine on
    RewriteCond %{HTTP:Authorization} .
    RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
</IfModule>

Then, restart Apache:

systemctl restart apache2

5.5. How to use a plugin 

Test the server with the HelloWorld plugin:

wget -q -O - "http://localhost/cgi-bin/qgis_mapserv.fcgi?SERVICE=HELLO"
 HelloServer!

You can have a look at the default GetCapabilities of the QGIS server at:

http://localhost/cgi-bin/qgis_mapserv.fcgi?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetCapabilities