all of the packages and tests work with both grpc and
drpc. we'll probably need to do some jenkins pipelines
to run the tests with drpc as well.
most of the changes are really due to a bit of cleanup
of the pkg/transport.Client api into an rpc.Dialer in
the spirit of a net.Dialer. now that we don't need
observers, we can pass around stateless configuration
to everything rather than stateful things that issue
observations. it also adds a DialAddressID for the
case where we don't have a pb.Node, but we do have an
address and want to assert some ID. this happened
pretty frequently, and now there's no more weird
contortions creating custom tls options, etc.
a lot of the other changes are being consistent/using
the abstractions in the rpc package to do rpc style
things like finding peer information, or checking
status codes.
Change-Id: Ief62875e21d80a21b3c56a5a37f45887679f9412
What: we move api keys out of the grpc connection-level metadata on the client side and into the request protobufs directly. the server side still supports both mechanisms for backwards compatibility.
Why: dRPC won't support connection-level metadata. the only thing we currently use connection-level metadata for is api keys. we need to move all information needed by a request into the request protobuf itself for drpc support. check out the .proto changes for the main details.
One fun side-fact: Did you know that protobuf fields 1-15 are special and only use one byte for both the field number and type? Additionally did you know we don't use field 15 anywhere yet? So the new request header will use field 15, and should use field 15 on all protobufs going forward.
Please describe the tests: all existing tests should pass
Please describe the performance impact: none
