Document the current Maven/Nexus/Apache configuration

We’ve successfully taken our Nexus instance off the internet, but the setup that we now have is quite complicated and it’s not obvious how it works or what you need to do, for example, to upload new artifacts on the rare occasions we still need to do so.

In particular, some artifacts are now stored under /efs/shibwww/nexus while others still live under ~nexus/sonatype-data/nexus/storage. The two locations are partially linked, but some links go in one direction and some in the other, making the final intent and future path unclear.

One specific issue I found hard to grok is that it looks like you can still use Nexus to upload some artifacts, but not others. In particular, the ~nexus/.../thirdparty directory is linked across to /efs/shibwww/nexus/old-thirdparty while Apache uses /efs/shibwww/nexus/thirdparty. So, you can upload an artifact to the thirdparty repository but it won’t be visible to Jenkins. Hilarity ensues.

We should document the intent, the current configuration and some level of “how-to” to cover any special upload cases, such as thirdparty. It’s also fine, of course, to use this as an opportunity to grind off some of the sharper corners and make the system simpler and therefore easier to document…