install libxml2-dev before PostGIS on Ubuntu

[Eric Jarvies]

In order to successfully install PostGIS on Ubuntu as is outlined here: ​https://docs.djangoproject.com/en/dev/ref/contrib/gis/install/#ref-gis-install one must first install libxml2-dev.

Eric Jarvies

[Aymeric Augustin]

There's a specific procedure for Ubuntu described here: ​https://docs.djangoproject.com/en/dev/ref/contrib/gis/install/#ubuntu-debian-gnu-linux If you follow it, apt-get will take care of the dependencies.

Now, if you're compiling stuff yourself, you obviously need make, gcc, etc. and you have to deal with dependencies manually. None of this is currently described in the documentation, maybe because we assume people who compile their own stuff instead of using the distribution's packages know what they're doing, maybe because we don't want to duplicate each library's installation instructions.

Sure, it couldn't hurt to add a line saying "you need libxml-dev", but is it the only dependency? Are you sure you didn't have other dependencies already installed? If we provide instructions on the dependencies, they must be complete.

I'm not sure how much detail we want to provide in this doc, but I see that it's not kept up to date very well (what about Debian 6?), so I think it should be kept simple. I'll let someone who is more familiar with GeoDjango decide.

[Ramiro Morales]

I agree with Aymeric. Just as an example, this is the list of packages one would need to install in order to be able to build the postgresql-8.4-postgis .deb package, were one goinf to build it from source but still using the Debian packages infrastructure: ​http://packages.ubuntu.com/source/lucid/postgis

It serves as an indication of what could be the the list of dependencies when starting from the postgis tarball.

There is no point in documenting only one dependency (libxml2-dev). I also think that documenting all of them is out of the scope of our docs.