setting up a koji stage env

[Mike McLean]

There are a number of ways one might use to set up a stage instance of 
koji that is based on a production instance. This is one that I have 
used on my koji systems.

The two major bits of data that koji contains are:
1) the koji db
2) /mnt/koji

With the db it is pretty easy to make a duplicate db based on a 
snapshot. The filesystem can be trickier. If you're lucky, your 
filesystem may support writable snapshots, in which case, awesome. 
Otherwise, you might like this approach.

Koji has supported the notion of split storage since 1.7.0. There's a 
brief summary of how that works here:

https://lists.fedoraproject.org/pipermail/buildsys/2012-May/003892.html

In this staging approach, we mount the production volume READ-ONLY on 
the staging systems, and make /mnt/koji/vol/prod on the _stage_ fs point 
to that RO mount.

When we restore the database from the production snapshot, we update the 
builds to point to the prod volume (seen the attached example script). 
The stage koji instance will then know where to find them.

Because the builds have changed locations, the old repodata becomes 
invalid, so all the repos need to be regenerated. The attached script 
just marks them expired (which should trigger the kojira running in 
stage to regen them).

The attached example sql script is based on one that I have used before. 
It will need to be adapted to your particular case.