fix(ex/Realtime.Server): use broadcast_local instead of broadcast (…

…#2856)

* fix(ex/Realtime.Server): use `broadcast_local` instead of `broadcast`

* fix: re-enable `DNSCluster`

Reverts: #2854

config/runtime.exs

@@ -105,7 +105,5 @@ if config_env() == :prod do
     config :skate, Skate.Detours.TripModificationPublisher, start: true
   end
 
-  # There are currently issues with Distributed Elixir and our Data Pipelines.
-  # So we need to disable clustering in prod until we figure this out
-  # config :skate, DNSCluster, query: System.get_env("DNS_CLUSTER_QUERY") || :ignore
+  config :skate, DNSCluster, query: System.get_env("DNS_CLUSTER_QUERY") || :ignore
 end

lib/realtime/server.ex

@@ -510,7 +510,7 @@ defmodule Realtime.Server do
         :alerts -> "realtime_alerts"
       end
 
-    Phoenix.PubSub.broadcast(pubsub_name(), topic, {:new_realtime_data, state.ets})
+    Phoenix.PubSub.local_broadcast(pubsub_name(), topic, {:new_realtime_data, state.ets})
   end
 
   @spec block_is_active?(VehicleOrGhost.t()) :: boolean