diskimage-builder/diskimage_builder/elements/debian/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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======
debian
======
Create an image based on Debian. We default to unstable but DIB_RELEASE
is mapped to any series of Debian.
Note that the default Debian series is `unstable`, and the default
mirrors for Debian can be problematic for `unstable`. Because apt does
not handle changing Packages files well across multiple out of sync
mirrors, it is recommended that you choose a single mirror of debian,
and pass it in via `DIB_DISTRIBUTION_MIRROR`.
If necessary, a custom apt keyring and debootstrap script can be
supplied to the `debootstrap` command via `DIB_APT_KEYRING` and
`DIB_DEBIAN_DEBOOTSTRAP_SCRIPT` respectively. Both options require the
use of absolute rather than relative paths.
Use of this element will also require the tool 'debootstrap' to be
available on your system. It should be available on Ubuntu, Debian,
and Fedora.
The `DIB_OFFLINE` or more specific `DIB_DEBIAN_USE_DEBOOTSTRAP_CACHE`
variables can be set to prefer the use of a pre-cached root filesystem
tarball.
The `DIB_DEBOOTSTRAP_EXTRA_ARGS` environment variable may be used to
pass extra arguments to the debootstrap command used to create the
base filesystem image. If --keyring is is used in `DIB_DEBOOTSTRAP_EXTRA_ARGS`,
it will override `DIB_APT_KEYRING` if that is used as well.
For further information about `DIB_DEBIAN_DEBOOTSTRAP_SCRIPT` ,
`DIB_DEBIAN_USE_DEBOOTSTRAP_CACHE` and `DIB_DEBOOTSTRAP_EXTRA_ARGS`
please consult "README.rst" of the debootstrap element.
-------------------
Note on ARM systems
-------------------
Because there is not a one-to-one mapping of `ARCH` to a kernel package, if
you are building an image for ARM on debian, you need to specify which kernel
you want in the environment variable `DIB_ARM_KERNEL`. For instance, if you want
the `linux-image-mx5` package installed, set `DIB_ARM_KERNEL` to `mx5`.