Due to timing, a transparent proxy could have two upstreams to dial
directly with the same address.
For example:
- The orders service can dial upstreams shipping and payment directly.
- An instance of shipping at address 10.0.0.1 is deregistered.
- Payments is scaled up and scheduled to have address 10.0.0.1.
- The orders service receives the event for the new payments instance
before seeing the deregistration for the shipping instance. At this
point two upstreams have the same passthrough address and Envoy will
reject the listener configuration.
To disambiguate this commit considers the Raft index when storing
passthrough addresses. In the example above, 10.0.0.1 would only be
associated with the newer payments service instance.
cbea3d203c