It has always been a weird thing that dib is a python package, but
is totally driven by the disk-image-create script. It creates this
strange division that is hard to explain.
This moves disk-image-create to a regular python entry-point
Currently, this simply exec()s the original disk-image-create script.
However, we now have a (private) interface between disk-image-create
written in python and the driver shell script. Here's some things we
could do, for example:
* Argument parsing is generally nicer in Python, and then end result
is mostly just setting environment variables to flag different things
in the shell script. I could see us moving the argument-parsing into
diskimage_builder.disk_image_create:main() and just setting things in
os.environ before the exec()).
* I7092e1845942f249175933d67ab121188f3511fd sets IMAGE_ELEMENT_YAML in
disk-image-create by calling-back to element-info. We can just call
element_dependencies.find_all_elements() in here an export is to
os.environ before disk-image-create starts.
* remove need for ramdisk-image-create symlink by just exporting
IS_RAMDISK based on sys.argv[1] value
* you could even unit test some of this :)
Change-Id: I69ca3d26fede0506a6353c077c69f735c8d84d28
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
