Fix the inconsistent hex value encoding for log metadata (#851)

* Fix the inconsistent hex value encoding for log metadata

* Format

* Dialyzer error

* Add test

Author: bryannaegele

apps/opentelemetry_api/lib/open_telemetry.ex

@@ -53,6 +53,16 @@ defmodule OpenTelemetry do
   """
   @type span_id() :: non_neg_integer()
 
+  @typedoc """
+  Hex-encoded TraceId as a 32-character lowercase binary string.
+  """
+  @type hex_trace_id() :: :opentelemetry.hex_trace_id()
+
+  @typedoc """
+  Hex-encoded SpanId as a 16-character lowercase binary string.
+  """
+  @type hex_span_id() :: :opentelemetry.hex_span_id()
+
   @type attribute_key() :: :opentelemetry.attribute_key()
   @type attribute_value() :: :opentelemetry.attribute_value()
 

apps/opentelemetry_api/lib/open_telemetry/span.ex

@@ -41,21 +41,33 @@ defmodule OpenTelemetry.Span do
   defdelegate span_id(span), to: :otel_span
 
   @doc """
-  Get the TraceId of a Span.
+  Get the hex-encoded trace context.
   """
-  @spec trace_id(OpenTelemetry.span_ctx()) :: OpenTelemetry.trace_id()
-  defdelegate trace_id(span), to: :otel_span
+  @spec hex_span_ctx(OpenTelemetry.span_ctx() | nil) ::
+          %{
+            otel_trace_id: OpenTelemetry.hex_trace_id(),
+            otel_span_id: OpenTelemetry.hex_span_id(),
+            otel_trace_flags: binary()
+          }
+          | %{}
+  defdelegate hex_span_ctx(span_ctx), to: :otel_span
 
   @doc """
   Get the lowercase hex encoded span ID.
   """
-  @spec hex_span_id(OpenTelemetry.span_ctx()) :: binary()
+  @spec hex_span_id(OpenTelemetry.span_ctx()) :: OpenTelemetry.hex_span_id()
   defdelegate hex_span_id(span), to: :otel_span
 
+  @doc """
+  Get the TraceId of a Span.
+  """
+  @spec trace_id(OpenTelemetry.span_ctx()) :: OpenTelemetry.trace_id()
+  defdelegate trace_id(span), to: :otel_span
+
   @doc """
   Get the lowercase hex encoded trace ID.
   """
-  @spec hex_trace_id(OpenTelemetry.span_ctx()) :: binary()
+  @spec hex_trace_id(OpenTelemetry.span_ctx()) :: OpenTelemetry.hex_trace_id()
   defdelegate hex_trace_id(span), to: :otel_span
 
   @doc """

apps/opentelemetry_api/src/otel_span.erl

@@ -112,15 +112,16 @@ span_id(#span_ctx{span_id=SpanId}) ->
     SpanId.
 
 %% keys are prefixed with `otel_' because the main use of this function is logger metadata
--spec hex_span_ctx(opentelemetry:span_ctx() | undefined) -> #{otel_trace_id := unicode:charlist(),
-                                                              otel_span_id := unicode:charlist(),
-                                                              otel_trace_flags := unicode:charlist()} | #{}.
-hex_span_ctx(#span_ctx{trace_id=TraceId,
-                       span_id=SpanId,
-                       trace_flags=TraceFlags}) ->
-    #{otel_trace_id => io_lib:format("~32.16.0b", [TraceId]),
-      otel_span_id => io_lib:format("~16.16.0b", [SpanId]),
-      otel_trace_flags => case TraceFlags band 1 of 1 -> "01"; _ -> "00" end};
+-spec hex_span_ctx(opentelemetry:span_ctx() | undefined) -> #{otel_trace_id := opentelemetry:hex_trace_id(),
+                                                              otel_span_id := opentelemetry:hex_span_id(),
+                                                              otel_trace_flags := binary()} | #{}.
+hex_span_ctx(SpanCtx = #span_ctx{trace_flags=TraceFlags}) ->
+    TraceIdBin = hex_trace_id(SpanCtx),
+    SpanIdBin = hex_span_id(SpanCtx),
+    TraceFlagsBin = case TraceFlags band 1 of 1 -> <<"01">>; _ -> <<"00">> end,
+    #{otel_trace_id => TraceIdBin,
+      otel_span_id => SpanIdBin,
+      otel_trace_flags => TraceFlagsBin};
 hex_span_ctx(_) ->
     #{}.
 

apps/opentelemetry_api/test/opentelemetry_api_SUITE.erl

@@ -247,7 +247,13 @@ noop_with_span(_Config) ->
     ok.
 
 hex_trace_ids(_Config) ->
+    HexTraceId = <<"0000000000000000000000000000a1b2">>,
+    HexSpanId = <<"000000000000c3d4">>,
     SpanCtx=#span_ctx{trace_id=41394, span_id=50132},
-    ?assertEqual(<<"0000000000000000000000000000a1b2">>, otel_span:hex_trace_id(SpanCtx)),
-    ?assertEqual(<<"000000000000c3d4">>, otel_span:hex_span_id(SpanCtx)),
+    ?assertEqual(HexTraceId, otel_span:hex_trace_id(SpanCtx)),
+    ?assertEqual(HexSpanId, otel_span:hex_span_id(SpanCtx)),
+    ?assertEqual(#{otel_trace_id => HexTraceId,
+                   otel_span_id => HexSpanId,
+                   otel_trace_flags => <<"00">>},
+                 otel_span:hex_span_ctx(SpanCtx)),
     ok.

apps/opentelemetry_experimental/src/otel_otlp_logs.erl

@@ -89,14 +89,26 @@ log_record(#{level := Level,
     DroppedAttributesCount = maps:size(Attributes) - length(Attributes1),
     Flags = 0,
 
-    LogRecord = case  Metadata of
-                    #{otel_trace_id := TraceId,
-                      otel_span_id := SpanId} ->
-                        #{trace_id => TraceId,
-                          span_id => SpanId};
-                    _ ->
-                        #{}
-                end,
+    %% Note: otel_trace_id and otel_span_id from hex_span_ctx are now binaries, not charlists.
+    LogRecord = case Metadata of
+        #{otel_trace_id := TraceId,
+          otel_span_id := SpanId,
+          otel_trace_flags := TraceFlagsHex} ->
+            TraceFlags = case TraceFlagsHex of
+                <<_:0, _/binary>> when byte_size(TraceFlagsHex) == 2 ->
+                    erlang:binary_to_integer(TraceFlagsHex, 16);
+                _ -> 0
+            end,
+            #{trace_id => TraceId,
+              span_id => SpanId,
+              trace_flags => TraceFlags};
+        #{otel_trace_id := TraceId,
+          otel_span_id := SpanId} ->
+            #{trace_id => TraceId,
+              span_id => SpanId};
+        _ ->
+            #{}
+    end,