Extract Spec File from RPM – How to Guide

The Fedora Packaging Guidelines have a draft document explaining how to handle SELinux in packages, and they use semanage. Without semanage, it looks like supporting RHEL 4 is going to be a hack, and there's no way around that.

According to the rpm 4.9.0 release notes, there has been some support directly in rpm for managing SELinux policies, but it has historically been broken:

• Older versions of RPM supported a %policy directive in spec for attaching SELinux policies into the package header, but this was never really usable for anything. Any uses of the %policy directive in specs should be removed as this unused directive prevents building with RPM 4.9.0 and later, while not doing anything for older versions.
• Starting with RPM 4.9.0, SELinux policy packaging is supported via new %sepolicy section in the spec. Such packages cannot be built, but are installable on older RPM versions too (but the included policies will not be used in any way).

I see no mention of file contexts there, and I haven't been able to find any mention of direct file context support (like %attr in the %files section). In any case, it looks like RHEL 6 is only on rpm 4.8.0, so (unless I've missed something) the semanage route is as good as we're going to be able to do at least until RHEL 7.

The problems you've had with alien are most likely not due to a bug or limitation in alien, but to an intrinsic problem of your approach. Converting a deb package into an rpm package is easy, and alien does it well. Converting a package for Ubuntu into a package for CentOS is much more difficult. This means not only repacking the files in a different format, but also moving files around to be in the directories where CentOS expects them, modifying configuration files so that they work on CentOS (e.g. with a different init system), declaring dependencies on packages that have different names (or might not even be present in the distribution at all), etc.

With 500 packages, you're probably going to encounter some difficult cases. Whether it's worth the effort to make dummy packages, create symbolic links and wrapper scripts, tweaking the system configuration, etc. is up to you, but I'd definitely be looking for another solution. In particular, note that there's a good chance that the Debian binariesare compiled against different library versions than what's present in CentOS.

If you want to run programs built for Debian on a CentOS machine, the least effort solution would be to install Debian in a chroot (this guide about installing Debian on another Debian version may be useful, as there's not much dependency on the host side).

If you want to have “proper” CentOS packages then building them from source will be far easier than converting the Debian packages.