11.1. Lesson: Installer QGIS Server

The goal for this lesson: To learn how to install QGIS Server on Debian Stretch. With negligible variations you can also follow it for any Debian based distribution like Ubuntu and its derivatives.

Note

Dans Ubuntu, vous pouvez utiliser votre utilisateur normal, en ajoutant sudo aux commandes nécessitant des autorisations d’administrateur. Dans Debian, vous pouvez travailler en tant qu’administrateur (root), sans utiliser sudo.

11.1.1. moderate Installer Follow Along: depuis les packages

In this lesson we’re going to do only the install from packages as shown here .

Installez QGIS Server avec:

apt install qgis-server
# if you want to install server plugins, also:
apt install python-qgis

QGIS Server should be used in production without QGIS Desktop (with the accompanying X Server) installed on the same machine.

11.1.2. moderate Follow Along: Exécutable QGIS Server

L’exécutable QGIS Server est qgis-mapserv.fcgi. Vous pouvez vérifier à quel endroit il a été installé au moyen de la commande: find / -name 'qgis_mapserv.fcgi' qui devrait renvoyer quelque chose comme /usr/lib/cgi-bin/qgis_mapserv.fcgi.

De manière facultative, si vous voulez tester l’exécutable en ligne de commande vous pouvez lancer: /usr/lib/cgi-bin/qgis_mapserv.fcgi, ce qui devrait produire un résultat semblable à:

QFSFileEngine::open: No file name specified
Warning 1: Unable to find driver ECW to unload from GDAL_SKIP environment variable.
Warning 1: Unable to find driver ECW to unload from GDAL_SKIP environment variable.
Warning 1: Unable to find driver JP2ECW to unload from GDAL_SKIP environment variable.
Warning 1: Unable to find driver ECW to unload from GDAL_SKIP environment variable.
Warning 1: Unable to find driver JP2ECW to unload from GDAL_SKIP environment variable.
Content-Length: 206
Content-Type: text/xml; charset=utf-8

<ServiceExceptionReport version="1.3.0" xmlns="https://www.opengis.net/ogc">
 <ServiceException code="Service configuration error">Service unknown or unsupported</ServiceException>
</ServiceExceptionReport>

C’est une bonne chose. Ce message signifie que nous sommes sur le bon chemin puisque le serveur répond que nous n’avons demandé aucun service supporté. Nous verrons plus loin comment faire des requêtes WMS.

11.1.3. Follow Along: Configuration HTTP du Serveur

Pour accéder au serveur QGIS depuis un navigateur internet, il faut mettre en place un serveur HTTP.

In this lesson we’re going to use the Apache HTTP server, colloquially called Apache.

First we need to install Apache by running the following command in a terminal:

apt install apache2 libapache2-mod-fcgid

You can run QGIS server on your default website, or configure a virtualhost specifically for this, as follows.

Dans le répertoire /etc/apache2/sites-available créons un fichier nommé qgis.demo.conf, avec ce contenu:

<VirtualHost *:80>
  ServerAdmin [email protected]
  ServerName qgis.demo

  DocumentRoot /var/www/html

  # Apache logs (different than QGIS Server log)
  ErrorLog ${APACHE_LOG_DIR}/qgis.demo.error.log
  CustomLog ${APACHE_LOG_DIR}/qgis.demo.access.log combined

  # Longer timeout for WPS... default = 40
  FcgidIOTimeout 120

  FcgidInitialEnv LC_ALL "en_US.UTF-8"
  FcgidInitialEnv PYTHONIOENCODING UTF-8
  FcgidInitialEnv LANG "en_US.UTF-8"

  # QGIS log (different from apache logs) see https://docs.qgis.org/testing/en/docs/user_manual/working_with_ogc/ogc_server_support.html#qgis-server-logging
  FcgidInitialEnv QGIS_SERVER_LOG_FILE /var/log/qgis/qgisserver.log
  FcgidInitialEnv QGIS_SERVER_LOG_LEVEL 0

  FcgidInitialEnv QGIS_DEBUG 1

  # default QGIS project
  SetEnv QGIS_PROJECT_FILE /home/qgis/projects/world.qgs

  # QGIS_AUTH_DB_DIR_PATH must lead to a directory writeable by the Server's FCGI process user
  FcgidInitialEnv QGIS_AUTH_DB_DIR_PATH "/home/qgis/qgisserverdb/"
  FcgidInitialEnv QGIS_AUTH_PASSWORD_FILE "/home/qgis/qgisserverdb/qgis-auth.db"

  # See https://docs.qgis.org/testing/en/docs/user_manual/working_with_vector/supported_data.html#pg-service-file
  SetEnv PGSERVICEFILE /home/qgis/.pg_service.conf
  FcgidInitialEnv PGPASSFILE "/home/qgis/.pgpass"

  # Tell QGIS Server instances to use a specific display number
  FcgidInitialEnv DISPLAY ":99"

  # if qgis-server is installed from packages in debian based distros this is usually /usr/lib/cgi-bin/
  # run "locate qgis_mapserv.fcgi" if you don't know where qgis_mapserv.fcgi is
  ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
  <Directory "/usr/lib/cgi-bin/">
    AllowOverride None
    Options +ExecCGI -MultiViews -SymLinksIfOwnerMatch
    Order allow,deny
    Allow from all
    Require all granted
  </Directory>

 <IfModule mod_fcgid.c>
 FcgidMaxRequestLen 26214400
 FcgidConnectTimeout 60
 </IfModule>

</VirtualHost>

You can do the above in a linux Desktop system by pasting and saving the above configuration after doing nano /etc/apache2/sites-available/qgis.demo.conf.

Note

Quelques unes des options de configuration sont expliquées dans la section Server Configuration avancée.

Créons maintenant les répertoires de stockage des logs de QGIS Server et de la base d’authentification.

mkdir /var/log/qgis/
chown www-data:www-data /var/log/qgis

mkdir /home/qgis/qgisserverdb
chown www-data:www-data /home/qgis/qgisserverdb

Note

www-data est l’utilisateur Apache sur les systèmes basés sur Debian et il faut qu’Apache accède à ces répertoires et aux fichiers qu’ils contiennent. La commande chown www-data... attribue la propriété des fichiers et répertoires à www-data.

Il est temps maintenant d’activer le Virtual host <https://httpd.apache.org/docs/2.4/vhosts>`_, le mode fcgid si ce n’est pas déjà le cas et de redémarrer le service apache2.

a2enmod fcgid
a2ensite qgis.demo
systemctl restart apache2

Note

Si vous avez installé QGIS Server sans serveur X (inclus avec Linux Desktop) et si vous voulez aussi utiliser la commande GetPrint alors il faut installer un serveur X factice et dire à QGIS Server de l’utiliser. Pour ce faire, il faut entre les commandes suivantes:

Installer xvfb:

apt install xvfb

Créer le fichier de service:

sh -c \
"echo \
'[Unit]
Description=X Virtual Frame Buffer Service
After=network.target

[Service]
ExecStart=/usr/bin/Xvfb :99 -screen 0 1024x768x24 -ac +extension GLX +render -noreset

[Install]
WantedBy=multi-user.target' \
> /etc/systemd/system/xvfb.service"

Activer, démarrer et vérifier le statut de xvfb.service:

systemctl enable xvfb.service
systemctl start xvfb.service
systemctl status xvfb.service

In the above configuration file there’s a FcgidInitialEnv DISPLAY ":99" that tells QGIS Server instances to use display no. 99. If you’re running the Server in Desktop then there’s no need to install xvfb and you should simply comment with # this specific setting in the configuration file. More info at https://www.itopen.it/qgis-server-setup-notes/.

Now that Apache knows that he should answer requests to http://qgis.demo we also need to setup the client system so that it knows who qgis.demo is. We do that by adding 127.0.0.1 qgis.demo in the hosts file. We can do it with sh -c "echo '127.0.0.1 qgis.demo' >> /etc/hosts". Replace 127.0.0.1 with the IP of your server.

Note

Remember that both the myhost.conf and /etc/hosts files should be configured for our setup to work. You can also test the access to your QGIS Server from other clients on the network (e.g. Windows or macOS machines) by going to their /etc/hosts file and point the myhost name to whatever IP the server machine has on the network. You can be sure that that specific IP is not 127.0.0.1 as that’s the local IP, only accessible from the local machine. On *nix machines the hosts file is located in /etc, while on Windows it’s under the C:\Windows\System32\drivers\etc directory. Under Windows you need to start your text editor with administrator privileges before opening the hosts file.

Nous pouvons tester un des serveur QGIS installé avec une requête http depuis la ligne de commande curl http://qgis.demo/cgi-bin/qgis_mapserv.fcgi qui devrait afficher en sortie :

<ServiceExceptionReport version="1.3.0" xmlns="https://www.opengis.net/ogc">
<ServiceException code="Service configuration error">Service unknown or unsupported</ServiceException>
</ServiceExceptionReport>

Note

curl can be installed with apt install curl.

Apache est maintenant configuré.

Also, from your web browser you can check the capabilities of the server:

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

11.1.4. moderate Follow Along: Créer un autre virtual host

Créons un autre virtual host Apache pointant sur QGIS Server. Vous pouvez choisir n’importe quel nom vous faisant plaisir (coco.bango, super.duper.training, example.com, etc.) mais pour faire simple nous allons choisir myhost.

  • Let’s set up the myhost name to point to the localhost IP by adding 127.0.0.1 x to the /etc/hosts with the following command: sh -c "echo '127.0.0.1 myhost' >> /etc/hosts" or by manually editing the file with gedit /etc/hosts.

  • Nous pouvons vérifier que myhost pointe sur le localhost en exécutant dans le terminal la commande ping myhost qui devrait afficher :

[email protected]:~$ ping myhost
PING myhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.024 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.029 ms
  • Voyons si nous pouvons accéder à QGIS Server depuis le site myhost en exécutant : curl http://myhost/cgi-bin/qgis_mapserv.fcgi ou en accédant à l’URL depuis le navigateur de votre box Debian. Vous obtiendrez probablement :

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>404 Not Found</title>
</head><body>
<h1>Not Found</h1>
<p>The requested URL /cgi-bin/qgis_mapserv.fcgi was not found on this server.</p>
<hr>
<address>Apache/2.4.25 (Debian) Server at myhost Port 80</address>
</body></html>
  • Apache doesn’t know that he’s supposed to answer requests pointing to the server named myhost. In order to setup the virtual host the simplest way would be to make a myhost.conf file in the /etc/apache2/sites-available directory that has the same content as qgis.demo.conf except for the ServerName line that should be ServerName myhost. You could also change where the logs go as otherwise the logs for the two virtual hosts would be shared but this is optional.

  • Let’s now enable the virtual host with a2ensite myhost.conf and then reload the Apache service with service apache2 reload.

  • Si vous essayez de nouveau d’accéder à http://myhost/cgi-bin/qgis_mapserv.fcgi vous verrez que tout fonctionne maintenant !

11.1.5. In Conclusion

Vous avez appris comment installer les différents versions de QGIS Server depuis les paquets, comment configurer Apache avec QGIS Server, sur Debian basé sur Linux.

11.1.6. What’s Next?

Now that you’ve installed QGIS Server and it’s accessible through the HTTP protocol, we need to learn how to access some of the services it can offer. The topic of the next lesson is to learn how to access QGIS Server WMS services.