tlsutil.Config already presents an excellent structure for this
configuration. Copying the runtime config fields to agent/consul.Config
makes code harder to trace, and provides no advantage.
Instead of copying the fields around, use the tlsutil.Config struct
directly instead.
This is one small step in removing the many layers of duplicate
configuration.
We have seen test flakes caused by 'concurrent map read and map write', and the race detector
reports the problem as well (prevent us from running some tests with -race).
The root of the problem is the grpc expects resolvers to be registered at init time
before any requests are made, but we were using a separate resolver for each test.
This commit introduces a resolver registry. The registry is registered as the single
resolver for the consul scheme. Each test uses the Authority section of the target
(instead of the scheme) to identify the resolver that should be used for the test.
The scheme is used for lookup, which is why it can no longer be used as the unique
key.
This allows us to use a lock around the map of resolvers, preventing the data race.