[Libguestfs] Initial look at porting febootstrap to SuSE

[Richard W.M. Jones]

I looked at OpenSUSE 11.3 (x86-64) and the 'zypper' package manager.

Background
----------

libguestfs needs febootstrap to build the so-called supermin
appliance.  Since febootstrap 3.x, this requires porting febootstrap
to each specific Linux package management system.  We've already done
this for yum (Fedora), apt (Debian/Ubuntu) and PacMan (ArchLinux).

A port is reasonably simple, provided your package manager supports
the following operations as *non-root*:

(1) Given a list of package names, we must be able to resolve all
    packages that have to be installed (recursively) to satisfy all
    dependencies.

    Made up example: ["dmidecode"] -> ["dmidecode", "glibc", "glibc-common"]

(2) Download a named package from the repository.

    (eg. in yum this corresponds to 'yumdownloader')

(3) Unpack the package and/or list files in the package and/or extract
    file(s) from the package.

    (eg. in RPM this is 'rpm2cpio')

SuSE
----

Zypper is quite a powerful package manager (based on a SAT solver).

Unfortunately the basic "zypper" program doesn't appear to support any
of (1), (2) or (3), and also most operations require root (eg.
"zypper install --download-only [package...]" unnecessarily needs
root).

However it also has an enormous C++ library component (libzypp).
[There are some language bindings for this too, but since they are
generated from SWIG they are fairly useless.]
http://gitorious.org/opensuse/libzypp

There are only very trivial examples in the library so it's hard to be
sure, but it appears that writing a dependency lister that runs as
non-root in C++ (ie. problem (1)) shouldn't be a huge problem.

Similarly there are some obscure code fragments in the git repo which
lead me to believe that it would be possible to write a non-root
package downloader in C++ (ie. problem (2)).

Problem (3) is already solved because rpm2cpio & cpio exist on SuSE.

Conclusion
----------

Someone motivated to add SuSE support to febootstrap and familiar with
libzypp could write the necessary extra tools in C++ in a short time.
To modify febootstrap, take one of the existing package management
modules as a starting point.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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