[Ubuntu] Stable update

[Sebastiaan Couwenberg]

On 04/29/2016 04:33 PM, Worth Lutz wrote:
> You mention dealing with the version in Ubuntu and the version in
> UbuntuGIS. This is always something I have not understood.
> 
> I've never understood the policies of how the versions come downstream
> from Debian to Ubuntu. What updates get made by DebianGIS? Do these flow
> down to Ubuntu? Or are Debian and Ubuntu stuck at a certain revision and
> a ppa like UbuntuGIS is used to provide updated packages?

The Debian GIS team updates the packaging as soon as possible after a
new upstream release is made. These packages are uploaded to Debian
unstable most often, or to experimental in case of pre-releases or new
releases that break the ABI and need a transition. Packages migrate from
the Debian unstable repository to the testing repositories after 5 to 10
days if the version is not affected by a Release Critical bug. After
about two years of development the package versions in the testing
repository get frozen in preparation of the new stable release, the
remaining release critical bugs get fixed after which the release is
published (installer images generated, documentation updates, etc).
Package revisions in the stable release remain frozen as they were in
the testing suite in preparation of the release. Only security fixes and
other important bugfixes are made to the packages in stable, this rules
out upgrading to new upstream releases. Some exceptions exists like
postgresql, mysql whose release engineering matches the Debian QA
requirements.

Ubuntu syncs new packages from Debian unstable as part of their
development cycle. For the unstable suite this is a mostly automatic
process. In preparation of a new release the development repository is
frozen and a similar process as for Debian releases follows. After
release only targeted fixes are included in packages.

The general flow of a new upstream releases into Debian and Ubuntu
releases is as follows:

 Upstream release
  ↳ Debian unstable → testing → stable
     ↳ Ubuntu development → release

The Debian GIS team maintains source packages for most of the packages
that are used in the UbuntuGIS PPA. Generally the process to update a
package in the UbuntuGIS PPA is to checkout the latest revision from the
Debian GIS git repository and create a no-change rebuild for the Ubuntu
LTS release in question. This is not an automatic process, it requires
some one involved in the UbuntuGIS team to prepare the builds for
Ubuntu. Because updates to packages in the UbuntuGIS PPA are not
governed by the strict rules for Ubuntu releases newer upstream versions
can be provided, the popularity of the PPA proves the need for newer
versions of the GIS packages than included in the Ubuntu releases.

Backports for the Debian stable releases provide in a similar need for
Debian stable users. Package revisions that have migrated to the testing
repository and meet other requirements are eligible for backporting. The
core libraries (gdal, geos, etc) are not good candidates for backports,
because all packages that depend on any of the libraries need to be
rebuilt for SONAME bumps and may need additional changes as well. Such
updates are included in UbuntuGIS increasing the burden for its
contributors because they need to manage those transitions themselves too.

Kind Regards,

Bas

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