diskimage-builder/elements/yum-minimal
Ian Wienand 3f3850aa0f Fixup RPM db path when building Fedora on Ubuntu
On Debian/Ubuntu installs of RPM, /usr/lib/rpm/macros sets

  %_dbpath  %(echo $HOME/.rpmdb)

which makes quite a bit of sense, because RPM is not the system
packager and thus RPM is setup to install things into a hierarchy in
the users homedir.

However, this messes things up when building a Fedora chroot on an
Ubuntu platform.

We use RPM & yum from the base-system to bootstrap the Fedora chroot.
While both obey --root flags, they still pick up the %_dbpath macro
and so end up creating the RPM database in <chroot>/home/user/.rpmdb

After we have bootstrapped yum/dnf, we execute further installation
commands from inside the chroot -- where we now have the Fedora
version of /usr/lib/rpm/macros and hence have _dbpath set to
/var/lib/rpm -- except there is no rpm database there.

Should anyone be finding this in the future, the actual issue that
appears is

  $ sudo chroot /opt/dib_tmp/image.b6B5S3f6/mnt dnf makecache
   Error: Failed to synchronize cache for repo 'fedora' from \
    'https://mirrors.fedoraproject.org/metalink?repo=fedora-$releasever&arch=x86_64': \
    Cannot prepare internal mirrorlist: file "repomd.xml" was not found in metalink

Note the issue there is that $releasever is not expanded, because the
rpmdb where this info is kept is not populated.

The trick is to make sure we override this value when using the host
rpm/yum to setup the chroot.  The bare rpm calls, which we use to
install the repos, have a --dbpath argument where we can override
this.  yum does not however, so we override this in the global
~/.rpmmacros while we are installing the packaging tools and
dependencies into the chroot.

Copious comments are included, because this is super-confusing.

Change-Id: I20801150ea02d1c64f118eb969fb2aec473476f7
2015-11-10 08:54:44 +00:00
..
install.d Add a yum-minimal element that just uses yum 2015-04-14 13:39:18 -04:00
pre-install.d Add a yum-minimal element that just uses yum 2015-04-14 13:39:18 -04:00
root.d Fixup RPM db path when building Fedora on Ubuntu 2015-11-10 08:54:44 +00:00
element-deps Add a yum-minimal element that just uses yum 2015-04-14 13:39:18 -04:00
package-installs.yaml Add a yum-minimal element that just uses yum 2015-04-14 13:39:18 -04:00
pkg-map Add a yum-minimal element that just uses yum 2015-04-14 13:39:18 -04:00
README.rst Add a yum-minimal element that just uses yum 2015-04-14 13:39:18 -04:00

===========
yum-minimal
===========
Base element for creating minimal yum-based images.

This element is incomplete by itself, you'll want to use the centos-minimal
or fedora-minimal elements to get an actual base image.

Use of this element will require 'yum' and 'yum-utils' to be installed on
Ubuntu and Debian. Nothing additional is needed on Fedora or CentOS.

The `DIB_OFFLINE` or more specific `DIB_YUMCHROOT_USE_CACHE`
variables can be set to prefer the use of a pre-cached root filesystem
tarball.