==============
debian-minimal
==============

Create a minimal image based on Debian. We default to unstable but `DIB_RELEASE`
can be set to any series of Debian.

There are two ways to configure apt-sources:

1. Using the standard way of defining the default, backports, updates
   and security repositories is the default. In this case you can
   overwrite the two environment variables to adapt the behavior:
   `DIB_DISTRIBUTION_MIRROR`: the mirror to use
      default: http://httpredir.debian.org/debian
   `DIB_DEBIAN_COMPONENTS`: (default) `main`
      a comma separated list of components. For Debian this can be
      e.g. `main,contrib,non-free`.

   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`.

   By default only `main` component is used. If
   `DIB_DEBIAN_COMPONENTS` (comma separated) from the `debootstrap`
   element has been set, that list of components will be used instead.

   Backports, updates and security are included unless `DIB_RELEASE`
   is `unstable`.

2. Complete configuration given in the variable
   `DIB_APT_SOURCES_CONF`.
   Each line contains exactly one entry for the sources.list.d
   directory.
   The first word must be the logical name (which is used as file name
   with `.list` automatically appended), followed by a colon `:`,
   followed by the complete repository specification.
   Example:
   DIB_APT_SOURCES_CONF=\
       "default:deb http://10.0.0.10/ stretch main contrib
        mysecurity:deb http://10.0.0.10/ stretch-security main contrib"

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. It is also recommended that the 'debian-keyring' package
be installed.

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.

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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`.
