diskimage-builder/diskimage_builder/elements/package-installs/README.rst
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

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================
package-installs
================
The package-installs element allows for a declarative method of installing and
uninstalling packages for an image build. This is done by creating a
package-installs.yaml or package-installs.json file in the element directory.
In order to work on Gentoo hosts you will need to manually install
`dev-python/pyyaml`.
example ``package-installs.yaml``
.. code-block:: YAML
libxml2:
grub2:
phase: pre-install.d
networkmanager:
uninstall: True
os-collect-config:
installtype: source
linux-image-amd64:
arch: amd64
dmidecode:
not-arch: ppc64, ppc64le
lshw:
arch: ppc64, ppc64le
example package-installs.json
.. code-block:: json
{
"libxml2": null,
"grub2": {"phase": "pre-install.d"},
"networkmanager": {"uninstall": true}
"os-collect-config": {"installtype": "source"}
}
Setting phase, uninstall, or installtype properties for a package overrides
the following default values::
phase: install.d
uninstall: False
installtype: * (Install package for all installtypes)
arch: * (Install package for all architectures)
Setting the installtype property causes the package only to be installed if
the specified installtype would be used for the element. See the
diskimage-builder docs for more information on installtypes.
The ``arch`` property is a comma-separated list of architectures to
install for. The ``not-arch`` is a comma-separated list of
architectures the package should be excluded from. Either ``arch`` or
``not-arch`` can be given for one package - not both. See
documentation about the ARCH variable for more information.
DEPRECATED: Adding a file under your elements pre-install.d, install.d, or
post-install.d directories called package-installs-<element-name> will cause
the list of packages in that file to be installed at the beginning of the
respective phase. If the package name in the file starts with a "-", then
that package will be removed at the end of the install.d phase.
Using post-install.d for cleanup
================================
Package removal is done in post-install.d at level 95. If you a
running cleanup functions before this, you need to be careful not
to clean out any temporary files relied upon by this element.
For this reason, generally post-install cleanup functions should
occupy the higher levels between 96 and 99.