If you want Hockeypuck to peer with other keyservers, you will need to populate your Hockeypuck instance to share as many public keys with prospective peers as possible before joining a pool of synchronizing key servers.
In Hockeypuck development and testing, I've used the sources listed at github.com/SKS-Keyserver/sks-keyserver/wiki/KeydumpSources.
hockeypuck-load -config /etc/hockeypuck/hockeypuck.conf /path/to/keyfiles/\*.pgp hockeypuck-pbuild -config /etc/hockeypuck/hockeypuck.conf
If you installed from PPA on Ubuntu, you'll want to do this as the hockeypuck
user:
su - hockeypuck -c 'hockeypuck-load -config /etc/hockeypuck/hockeypuck.conf /path/to/keyfiles/\*.pgp; \ hockeypuck-pbuild -config /etc/hockeypuck/hockeypuck.conf'