Building EL6 with koji/mock on a EL5.5 host

[Brian_Kosick at McAfee.com]

Hi All,

I'm trying to build el6 on a koji build host that is el5.5.   

I'm running into issues in the mock environment with rpm and what version of BDB it is using.  Basically, I was originally having issues with yum failing on deps of rpmlib(PayLoadIsXZ), so after a little research I found this link from a list:  http://infrastructure.fedoraproject.org/builder-rpms/x86_64/.   These rpms (basically a intermediate version of rpm that supports XZ compression) got me around the missing rpm libs and on to mock exiting complaining about not being able to read the rpm __db files.   I believe that I have correctly diagnosed the issue here; that the versions of __db files that the rpm 4.6 (from the link) produces is not liked by the rpm (4.8) of the el6 mock root.   From what I've gleaned about mock is that there is no easy way to get around this rpm db incompatibility.   And there is no such mock option that will let you do the equivalent of "rpm /var/lib/rpm/__db* && rpm --rebuilddb".  Has anyone run into this before?  And if so how did you address/handle it?   

I believe that what I may want to do is create a el6 build host and use channels to control which host builds the el6 dist tag.      However, I cannot seem to find information on how to create and use custom channels with koji and only vague references to the concept of channels in koji.   For instance my questions would be:

How to create a new channel?
How to associate a tag/target/dist with a channel?
I'm assuming that the koji add-host-to-channel command would add the new el6 host correctly, but how to then remove the the new host from the "default" channel so that it doesn't build el5 and which,. I suspect, would have the same rpm db issues in reverse.

Thanks,
Brian