diskimage-builder/diskimage_builder/elements/apt-preferences
Ian Wienand 97c01e48ed Move elements & lib relative to diskimage_builder package
Currently we have all our elements and library files in a top-level
directory and install them into
<root>/share/diskimage-builder/[elements|lib] (where root is either /
or the root of a virtualenv).

The problem with this is that editable/development installs (pip -e)
do *not* install data_files.  Thus we have no canonical location to
look for elements -- leading to the various odd things we do such as a
whole bunch of guessing at the top of disk-image-create and having a
special test-loader in tests/test_elements.py so we can run python
unit tests on those elements that have it.

data_files is really the wrong thing to use for what are essentially
assets of the program.  data_files install works well for things like
config-files, init.d files or dropping documentation files.

By moving the elements under the diskimage_builder package, we always
know where they are relative to where we import from.  In fact,
pkg_resources has an api for this which we wrap in the new
diskimage_builder/paths.py helper [1].

We use this helper to find the correct path in the couple of places we
need to find the base-elements dir, and for the paths to import the
library shell functions.

Elements such as svc-map and pkg-map include python unit-tests, which
we do not need tests/test_elements.py to special-case load any more.
They just get found automatically by the normal subunit loader.

I have a follow-on change (I69ca3d26fede0506a6353c077c69f735c8d84d28)
to move disk-image-create to a regular python entry-point.

Unfortunately, this has to move to work with setuptools.  You'd think
a symlink under diskimage_builder/[elements|lib] would work, but it
doesn't.

[1] this API handles stuff like getting files out of .zip archive
modules, which we don't do.  Essentially for us it's returning
__file__.

Change-Id: I5e3e3c97f385b1a4ff2031a161a55b231895df5b
2016-11-01 17:27:41 -07:00
..
extra-data.d Move elements & lib relative to diskimage_builder package 2016-11-01 17:27:41 -07:00
README.rst Move elements & lib relative to diskimage_builder package 2016-11-01 17:27:41 -07:00

apt-preferences

This element generates the APT preferences file based on the provided manifest provided by the ../manifests/README element.

The APT preferences file can be used to control which versions of packages will be selected for installation. APT uses a priority system to make this determination. For more information about APT preferences, see the apt_preferences(5) man page.

Environment Variables

DIB_DPKG_MANIFEST:
Required

No

Default

None

Description

The manifest file to generate the APT preferences file from.

Example

DIB\_DPKG\_MANIFEST=~/image.d/dib-manifests/dib-manifest-dpkg-image