Namespace To Do: Implement Auto Discovery

[joereuss12]

As discussed in the weekly Pelican meeting, we need to implement a way for the namespace to automatically discover registered public keys.

[bbockelm]

@jhiemstrawisc - I think this is 90% done. I think, once #30 is merged, we just need to do end-to-end testing with the director and an origin.

For example, last I tested this functionality, the JWKS public key fetching code in the origin didn't like the public key JWKS that the namespace client was generating (it was missing at least kty if not other metadata). So, finishing off the item is likely just finding all the remaining small bugs in the end-to-end testing.

[bbockelm]

@jhiemstrawisc -- we're down to this one last issue for 7.0.0. How's the end-to-end testing going?

[jhiemstrawisc]

I got to this yesterday afternoon and encountered two issues:

1. I can't get the origin to run. When I do osdf origin serve -v /test:/jhiemstra/test --config /etc/pelican/pelican.yaml -d, the origin crashes with a note Error: xrootd process failed unexpectedly: exit status 1. Sometimes it's CMSD that fails. Going through the output, it looks like TLS initialization is the culprit, even though I have my pelican config pointed to tls.crt and tls.key that were auto-generated in /etc/pelican/certificates. I've tried running this both as root and as my local xrootd user.
2. Because we wound up having to break out the Director into a cache and an origin endpoint, we need a way to advertise to both. I don't think the current origin will do that (although because of 1 I haven't been able to test or start fixing).

[jhiemstrawisc]

See PR #121. Awaiting review and a few last cleanup items that need input.