[Yum] complete install of system using yum?

[Eric V. Smith]

>> Now, would it be possible to basically install this system completely
>> from say a set of RedHat 9 RPMS, if you had a known set of packages
>> you wanted to install (not necessarily using comps.xml). That way, yum
>> could not only install the system (post bootstrap), but keep it up to
>> date all over the network?
>
> yes.

I have a similar question I've been meaning to ask.  I've read somewhere
that Duke uses yum to completely maintain machines, which I assume means
also maintaining config files.  How is this done, when the config files
differ per-machine?

For one example, I have a large number of machines that have postfix
installed.  Each machine has a different main.cf config file.  On my yum
repository I can determine what I want this file to be, but how do I get
this into a file on each client?  Should I create a little RPM that
depends on postfix (so it runs after postfix is installed), and have it
run a script that generates main.cf?  What do I do if the config file
needs to change?  How do I re-run the script in this RPM?  I'm looking for
what the best practice here might be.

Thanks in advance.

Eric.