12.1. Lesson: Install 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.

Poznámka

In Ubuntu you can use your regular user, prepending sudo to commands requiring admin permissions. In Debian you can work as admin (root), without using sudo.

12.1.1. moderate Follow Along: Install from packages

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

Install QGIS Server with:

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 accompagning X Server) installed on the same machine.

12.1.2. moderate Follow Along: QGIS Server Executable

The QGIS Server executable is qgis_mapserv.fcgi. You can check where it has been installed by running find / -name 'qgis_mapserv.fcgi' which should output something like /usr/lib/cgi-bin/qgis_mapserv.fcgi.

Optionally, if you want to do a command line test at this time you can run the /usr/lib/cgi-bin/qgis_mapserv.fcgi command which should output something like:

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>

This is a good thing, it tells you we’re on the right track as the server is saying that we haven’t asked for a supported service. We’ll see later on how to make WMS requests.

12.1.3. Follow Along: HTTP Server Configuration

In order to access on the installed QGIS server from an Internet Browser we need to use an HTTP server.

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.

In the /etc/apache2/sites-available directory let’s create a file called qgis.demo.conf, with this content:

<VirtualHost *:80>
  ServerAdmin webmaster@localhost
  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.

Poznámka

See some of the configuration options are explained in the Server Advanced configuration section.

Let’s now create the directories that will store the QGIS Server logs and the authentication database:

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

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

Poznámka

www-data is the Apache user on Debian based systems and we need Apache to have access to those locations or files. The chown www-data... commands changes the owner of the respective directories and files to www-data.

We can now enable the virtual host, enable the fcgid mod if it’s not already enabled and restart the apache2 service:

a2enmod fcgid
a2ensite qgis.demo
service apache2 restart

Poznámka

If you installed QGIS Server without running an X Server (included in Linux Desktop) and if you also want to use the GetPrint command then you should install a fake X Server and tell QGIS Server to use it. You can do that by running the following commands.

Install xvfb:

apt install xvfb

Create the service file:

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"

Enable, start and check the status of the 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.

Poznámka

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.

We can test one of the installed qgis servers with a http request from command line with curl http://qgis.demo/cgi-bin/qgis_mapserv.fcgi which should output:

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

Poznámka

curl can be installed with apt install curl.

Apache is now configured.

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

12.1.4. moderate Follow Along: Create another virtual host

Let’s create another Apache virtual host pointing to QGIS Server. You can choose whatever name you like (coco.bango, super.duper.training, example.com, etc.) but for simplicity sake we’re going to use 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.

  • We can check that myhost points to the localhost by running in the terminal the ping myhost command which should output:

qgis@qgis:~$ 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

  • Let’s try if we can access QGIS Server from the myhost site by doing: curl http://myhost/cgi-bin/qgis_mapserv.fcgi or by accessing the url from your Debian box browser. You will probably get:

<!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.

  • If you try again to access the http://myhost/cgi-bin/qgis_mapserv.fcgi url you’ll notice everything is working now!

12.1.5. In Conclusion

You learned how to install different QGIS Server versions from packages, how to configure Apache with QGIS Server, on Debian based Linux distros.

12.1.6. What’s Next?

Now that you’ve installed QGIS Server and it’s accesible 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.