"Layered" build system

[Avi Kivity]

Hello,

I'd like to use koji as a layered build system.  I'm not sure that this is the right place, or that koji is the right tool.  If not, please let  me know what is.

We are building rpms against Fedora and CentOS/RHEL 7.  While all our dependencies are in Fedora, that's not the case for RHEL.  We would like to store our dependencies (updated rarely) as well as our product packages (updated often) in our local koji, but we'd like the rest of the distribution to be picked up from upstream, rather than having to import (and keep updating) all of our upstream dependencies into our local koji instance.

To make the case concrete, our non-upstream dependencies include gcc 5.3 (included in Fedora 23, but not in RHEL), binutils and isl (dependencies of gcc), boost (we need a later version than is available), ninja-build, ragel, gdb, and pyparsing.

Currently, we just regenerate them each build.  Ideally we pull them from our local koji instance.

Avi