Rate limit service
The rate limit service configuration specifies the global rate limit service Envoy should talk to when it needs to make global rate limit decisions. If no rate limit service is configured, a “null” service will be used which will always return OK if called.
gRPC service IDL
Envoy expects the rate limit service to support the gRPC IDL specified in rls.proto. See the IDL documentation for more information on how the API works. See Envoy’s reference implementation here.