[osgeo4w-dev] osgeo4w portability

[Müller, Andreas, Dr. phil.]

Hi Matt and Alex and all readers,
First: I hope this post fits in the right place, because i had no mail to respond to...

I asked Matt at github, https://github.com/maphew/apt/issues/10#issuecomment-73048724, because i wanted his apt.py to work on a portable install for OSGeo4W packages. So he opened this thread. Thank you for that!

To have a portable OSGeo4W, you could easily copy from an installed version. Much works, but it is not really portable. For eg. you should start QGIS with option configpath, like --configpath "%HOME%\.qgis". That prevents QGIS to write to the Windows-Registry.

There are attempts to build a portable gqis, osgeo4w Version, but, like the one mentioned by Alex, http://www.archaeogeek.com/blog/2014/01/20/portable-gis-v4/, it lacks, as far as i know, a possibility to choose and update packages. That's the point, where apt.py, as a package manager, joins the game! (because i'm more comfortable with python than with perl, thanks for the code of "creatensis.pl" by jef-n on github)

Unfortunately nearly all packages go through the postinstall stage of installation. Here, bat files in etc/postinstall are called, mainly to replace patterns like @osgeo4w@ to hard codes paths, which we don't want in a portable install. One tool to do that is textreplace, which turns @osgeo4w@ into the string stored in the environment variable %OSGEO4W_ROOT%.

For example apache:
in etc/postinstall we find apache.bat and inside
textreplace -sf apache/conf/httpd.conf -df apache/conf/httpd.conf -map @osgeo4w@ %OSGEO4W_ROOT%
which changes the pattern in http.conf. 
A portable version would be
textreplace -sf apache/conf/httpd.conf -df apache/conf/httpd.conf -map @osgeo4w@ ${OSGEO4W_ROOT}
now it's up to apache to find the path through the environment variable.

A lot of packages make use of textreplace, i didn't check them all. And there are cases, where something different is wanted to happen, where software must be installed to the System, like Visual-C Re-distributables.

What i'm asking for, is there a way to deal with postinstall-issues, even if i can't predict which package is to be installed.

One solution would be to delegate that through the Packaking-instructions (https://trac.osgeo.org/osgeo4w/wiki/PackagingInstructions). But is this realistic?


if someone interested or willing to help, i can show the cases i found, during my version of a "portable installer".

Best Regards,
Andreas

Dr. Andreas Müller -_- Universität Trier - FB VI - Kartographie, muellea at uni-trier.de
54286 Trier, Behringstr. 29, F 191, ++496512014576