GEOS-11684: base image does not include GDAL

[stacy-rendall]

Further notes/discussion: https://osgeo-org.atlassian.net/browse/GEOS-11684

Since the base image was changed from Ubuntu to Tomcat it no longer includes GDAL, which is required for GDAL/OGR extensions.

The rationale behind this PR is to enable installing GDAL without affecting (i.e. increasing the size of) the initial image.

This PR:

• adds/documents an INSTALL_GDAL environment variable
• prior to installing extensions in startup.sh:
  • check if INSTALL_GDAL=true
  • check if gdal-bin is already installed
  • modify permissions on /tmp to enable apt-get update (initially the directory is not writable, which will cause update to fail)
  • update and install gdal-bin, including recommended packages (notably proj)
  • restore /tmp permissions

Happy to discuss if an alternative approach might be more appropriate.

[aaime]

Would it enable usage of the GDAL extensions though? AFAIK the gdal-java JNI binding library is needed to support that case, which is no longer packaged in Debian based distributions, see this OSGeo-Live discussion for links and workarounds.

[buehner]

I'd also like to know whether apt-get install -y gdal-bin already solves your problem and makes your extension (OGR based WFS Output Format) fully work. Can you confirm this @stacy-rendall ?

I never really had such a use case myself, but I know from others - like @aaime also mentioned - that the GDAL Java bindings are required for some GDAL based extensions/scenarios, which requires some more work.

• https://gdal.org/en/stable/api/java/index.html
• https://gdal.org/en/stable/development/building_from_source.html#building-from-source-java

This could also blow up a resulting image. It would be great to find a solution with full GDAL support. Maybe it also makes sense to provide two GS Docker Image flavors then:

• the basic one (like now)
• an GS Docker Image with full GDAL support (incl. bindings) (-> bigger footprint)

I will try to find some time soon to dive deeper into this GDAL world...

[stacy-rendall]

Just tested it all again with a clean image: apt-get install -y gdal-bin alone is enough for the ogr-wfs extension to basically work - it only seems to require that "ogr2ogr is available in the path".

To be clear: it is working equivalently for my use case as what it was with the image <= 2.25.3, i.e. prior to the base image changing.

Not sure if I can claim that it is "fully working" - I can't seem to get the extension to transform SRS on any version I have tested (2.25.3 or 2.25.5) - but I'm not sure if that is due to me or an issue with the extension.

[buehner]

I found some time for the GDAL Java Bindings. See here: #138