WFS Provider WARNING - Cannot create temporary SpatiaLite cache when using flatpak install

[palmerj]

Describe the bug
When using the flatpak version of QGIS 3.12.2 on Ubuntu and adding any WFS layer I get the following error:

WARNING    Cannot create temporary SpatiaLite cache.

I have set the networking cache directory to ~/qgis/cache and ensure the directory actually has 0777 right to ensure it's not some permissions issue. I note the the following empty directory gets created: ~/.qgis/cache/wfsprovider/pid_2

I'm wondering if this issue is caused by permissions sandboxing as implemented by flatpak.

QGIS and OS versions

QGIS version
3.12.2-Bucuresti
QGIS code revision
8a1fb33
Compiled against Qt
5.14.2
Running against Qt
5.14.2
Compiled against GDAL/OGR
3.0.4
Running against GDAL/OGR
3.0.4
Compiled against GEOS
3.8.1-CAPI-1.13.3
Running against GEOS
3.8.1-CAPI-1.13.3
Compiled against SQLite
3.29.0
Running against SQLite
3.29.0
PostgreSQL Client Version
12.2
SpatiaLite Version
4.3.0a
QWT Version
6.1.4
QScintilla2 Version
2.10.8
Compiled against PROJ
6.3.1
Running against PROJ
Rel. 6.3.1, February 10th, 2020
OS Version
KDE Flatpak runtime
Active python plugins
MetaSearch;
db_manager;
processing

[nyalldawson]

The flatpak install isn't officially supported. You'll need to file this with the maintainers of that package.

[palmerj]

It's on the download pages as is mentioned as "There is an experimental QGIS flatpak for QGIS Stable available." Where do you state this is not officially supported?

Also I suspect a change in the core of QGIS can fix this, or at least given better information as to why it has failed

[nyalldawson]

Ah - i wasn't aware we were pointing users towards it. Not sure who here has experience with that particular package though -- I still think you'd have more luck asking over at flathub.

[palmerj]

I'm wondering if it's got anything to do with the GDAL vsimem file handler and how it's implemented. The flatpak QGIS configuration is very permissive and allow access to pretty much all of the host operating system files for read as write.

[palmerj]

I still think you'd have more luck asking over at flathub.

I've also done that. Thanks

[rouault]

I'm wondering if it's got anything to do with the GDAL vsimem file handler and how it's implemented

Very unlikely. /vsimem/ as its name suggest is a pure in-memory thing: no access to the (real) file system !

The flatpak QGIS configuration is very permissive and allow access to pretty much all of the host operating system files for read as write.

Well, that should be a "good" thing for the purpose of making standard QGIS code work.

Someone wanting to debug that would have to step into QgsBackgroundCachedSharedData::createCache() (assuming this is possible in this environment) and see where it exists exactly

[palmerj]

Thanks Even. Lots like debugging is possible: https://github.com/flatpak/flatpak/wiki/Tips-&-Tricks. I will raise with flatpak people.

[palmerj]

Ok issue found. The flatpak build needs GDAL/OGR built with spatialite support:

Warning 6: driver SQLite does not support creation option SPATIALITE
ERROR 6: OGR was built without libspatialite support
... sorry, creating/writing any SpatiaLite DB is unsupported