[bugfix][server] Fix prefix path for server

[elpaso]

Fixes #18230 - service configuration error (service unknown or unsupported)

I thought about placing the fix into the server code, but I believe
that it's much more cleaner here: otherwise we'd need to adjust all
other paths after they have been uncorrectly set by the application
init() code.

Note that it is always possible to override the path with an environment variable.

[pblottiere]

Nice, thank you @elpaso 👍! We encountered this issue with @elemoine when we tried qgis server 3 from debian packages (and we had to correctly set QGIS_PREFIX_PATH environment variable to make it work).

[ponceta]

In qgis 3.0.1 actual official package (on ubuntu 17.10), it is still required to fix it using something like

  # FIX path to library see https://issues.qgis.org/issues/18230
  FcgidInitialEnv QGIS_PREFIX_PATH "/usr" 

[umbe1987]

Is this still a problem? I am experiencing the same issue as in 3liz/lizmap-web-client#793 on my fresh Ubuntu Server 18.04 install and qgis-server/bionic,now 1:3.4.0+28bionic amd64.

Unfortunately, adding FcgidInitialEnv QGIS_PREFIX_PATH "/usr" to my qgis.demo.conf file and restart apache didn't make it work.

My test was:

• downloading the demo files from https://github.com/qgis/QGIS-Training-Data
• extracting the qgis-server-tutorial-data in my server's folder (mine is /home/ubuntu/projects/)
• curl http://qgis.demo/cgi-bin/qgis_mapserv.fcgi?SERVICE=WMS%26VERSION=1.3.0%26REQUEST=GetCapabilities%26map=/home/ubuntu/qgis/projects/qgis-server-tutorial-data/world.qgs

The output I am receiving (before and after the QGIS_PREFIX_PATH workaround) is:

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

P.S.: I also tried with v2.0 of the demo data but still the same exception.

[umbe1987]

I also added a note in the original bug https://issues.qgis.org/issues/18230#note-13

[umbe1987]

Sorry, everything was ok with my config and QGIS SERVER.
Thanks to gis.stackoverflow comment to my question
https://gis.stackexchange.com/questions/301305/qgis-server-3-service-service-unknown-or-unsupported?noredirect=1#comment485177_301305
, I found out the problem was in the way I created my URL request and CURL.
Instead of doing curl
http://qgis.demo/cgi-bin/qgis_mapserv.fcgi?SERVICE=WMS%26VERSION=1.3.0%26REQUEST=GetCapabilities%26map=/home/ubuntu/qgis/projects/test_qgis/milano_test.qgs
I had to do curl
"http://qgis.demo/cgi-bin/qgis_mapserv.fcgi?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetCapabilities&map=/home/ubuntu/qgis/projects/test_qgis/milano_test.qgs"
no %26 instead of &, and the entire URL within double quotes.