fix: quiet benign ThinPool port exits and keyless OTLP export

ThinPool traps exits (for terminate/2 device teardown), so the normal close
of each System.cmd port arrived as an unhandled {:EXIT, port, :normal} and
logged as an error. Add a handle_info clause to ignore normal exits.

Tracing defaulted to Honeycombs endpoint but only sent the auth header when
HONEYCOMB_API_KEY was set, so keyless runs 401d on every batch. Export only
when a key or a custom OTEL endpoint is configured; otherwise disable the
exporter.

Author: markovejnovic

config/runtime.exs

@@ -14,17 +14,27 @@ config :hyper, Hyper.Node.Config.Budget,
 # Where to send traces. Defaults to Honeycomb; override OTEL_EXPORTER_OTLP_*
 # to point at any OTLP/HTTP backend (Collector, Grafana, etc).
 if config_env() != :test do
-  endpoint = System.get_env("OTEL_EXPORTER_OTLP_ENDPOINT", "https://api.honeycomb.io")
+  custom_endpoint = System.get_env("OTEL_EXPORTER_OTLP_ENDPOINT")
+  api_key = System.get_env("HONEYCOMB_API_KEY")
 
-  headers =
-    case System.get_env("HONEYCOMB_API_KEY") do
-      nil -> []
-      "" -> []
-      key -> [{"x-honeycomb-team", key}]
-    end
+  cond do
+    api_key not in [nil, ""] ->
+      config :opentelemetry_exporter,
+        otlp_protocol: :http_protobuf,
+        otlp_endpoint: custom_endpoint || "https://api.honeycomb.io",
+        otlp_headers: [{"x-honeycomb-team", api_key}]
 
-  config :opentelemetry_exporter,
-    otlp_protocol: :http_protobuf,
-    otlp_endpoint: endpoint,
-    otlp_headers: headers
+    custom_endpoint not in [nil, ""] ->
+      # A custom OTLP backend (e.g. a local Collector) needs no Honeycomb key.
+      config :opentelemetry_exporter,
+        otlp_protocol: :http_protobuf,
+        otlp_endpoint: custom_endpoint,
+        otlp_headers: []
+
+    true ->
+      # No backend configured: exporting to the Honeycomb default with no key
+      # 401s on every batch. Stay silent instead (typical for local dev). Set
+      # HONEYCOMB_API_KEY or OTEL_EXPORTER_OTLP_ENDPOINT to enable tracing.
+      config :opentelemetry, traces_exporter: :none
+  end
 end

lib/hyper/node/img/thin_pool.ex

@@ -94,6 +94,13 @@ defmodule Hyper.Node.Img.ThinPool do
     {:reply, :ok, id_free(state, id)}
   end
 
+  @impl true
+  # Each privileged command runs through `System.cmd`, which links a transient
+  # port to this process; because we trap exits (for `terminate/2` teardown),
+  # the port's normal close is delivered here. Ignore it. An abnormal exit
+  # carries a non-`:normal` reason and falls through to the default handler.
+  def handle_info({:EXIT, _port, :normal}, state), do: {:noreply, state}
+
   @impl true
   def terminate(_reason, state) do
     _ = SuidHelper.Dmsetup.remove(@pool_name)