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
Since the ironic-agent element builds the ramdisk and extracts the
kernel itself, there's no need to actually generate an image at the
end of the process. Previously the unnecessary image was being
deleted, but this wastes a bunch of time compressing and converting
the image. It's better to just not create the image at all.
This change adds a noop element called no-final-image that
disk-image-create looks for in the element list and, if found, will
cause it to skip the final image generation. This is more flexible
than the previous ironic-agent-specific method that would have
required changes to disk-image-create for every element that wanted
to behave similarly.
Note that this cannot be done using an environment variable, because
element environments.d entries do not propagate out to
disk-image-create. It also doesn't make sense as a user option
because it should be set by the element author, not the user.
Change-Id: I168feb18f0d578b3babbe4784d3ef75e755e1ebd
