12.1. Lesson: Instalarea Serverului QGIS¶

12.1.1. Follow Along: Instalarea pachetelor¶

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

First add the QGIS repository by creating the /etc/apt/sources.list.d/debian-qgis.list file with the following content:

# latest stable
deb http://qgis.org/debian stretch main
deb-src http://qgis.org/debian stretch main

After you add the qgis.org repository public key to your apt keyring (follow the above link on how to do it) you can run the apt-get update command to refresh the packages list and apt-get dist-upgrade to upgrade the packages.

Instalați Serverul QGIS cu:

apt-get install qgis-server 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. Follow Along: Executabilul Serverului QGIS¶

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="http://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-get install apache2 libapache2-mod-fcgid.

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 http://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 http://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 sudo nano /etc/apache2/sites-available/qgis.demo.conf.

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

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

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

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

sudo a2enmod fcgid
sudo a2ensite qgis.demo
sudo service apache2 restart

sudo apt-get install xvfb

Create the service file:

sudo 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:

sudo systemctl enable xvfb.service
sudo systemctl start xvfb.service
sudo 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 http://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 sudo sh -c "echo '127.0.0.1 qgis.demo' >> /etc/hosts". Replace 127.0.0.1 with the IP of your server.

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

Acum, Apache este configurat.

12.1.4. Follow Along: Crearea unei gazde virtuale¶

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: sudo sh -c "echo '127.0.0.1 myhost' >> /etc/hosts" or by manually editing the file with sudo 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/apache/sites-available directory that has the same content as file: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 sudo apt-get a2ensite myhost.conf and then reload the Apache service with sudo systemctl reload apache2.
• 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.