Instead of endpoints being a flat list, it is now a list of "subsets"
where each is a struct of {Addresses, Ports}. To generate the list of
endpoints you need to take union of the Cartesian products of the
subsets. This is compact in the vast majority of cases, yet still
represents named ports and corner cases (e.g. each pod has a different
port number).
This also stores subsets in a deterministic order (sorted by hash) to
avoid spurious updates and comparison problems.
This is a fully compatible change - old objects and clients will
keepworking as long as they don't need the new functionality.
This is the prep for multi-port Services, which will add API to produce
endpoints in this new structure.
As far as I know, nobody uses it. It was replaced by PublicIPs. If I were
being very polite I would leave it in internal, but since I am 99.99% sure
nobody uses it, I am cutting it. Let's argue about it.
It was an ABA problem where the proxy loop might see its own service as
"existing" when it had been destroyed and recreated (as in an update).
To prove this I added a counter of running ProxyLoop goroutines and check that
in tests. If I undo my main change, the tests fail. This makes the
proxier_test significantly slower (3 seconds vs 0.5 seconds). Sorry.
After this DNS is resolvable from the host, if the DNS server is targetted
explicitly. This does NOT add the cluster DNS to the host's resolv.conf. That
is a larger problem, with distro-specific tie-ins and circular deps.
This change includes minor refactoring and cleanup of the proxy
package including the following items:
* Rename source files with misspelling of round robin
* Remove unnecessary and redundant comments
* Update comments for clarity
* Add locking when updating the round-robin index
* Improve method receiver names
* Rename the LoadBalance method to NextEndpoint to add clarity
No changes in behaviour have been introduced.
