Merge pull request #174 from nblumhardt/record-structure-type-tag

Add an option to include `StructureValue.TypeTag` as `$type` when converting to OTLP maps

Author: nblumhardt

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.401",
+    "version": "9.0.200",
     "allowPrerelease": false,
     "rollForward": "latestFeature"
   }

src/Serilog.Sinks.OpenTelemetry/Sinks/OpenTelemetry/IncludedData.cs

@@ -13,6 +13,8 @@
 // limitations under the License.
 
 using System.Diagnostics;
+using OpenTelemetry.Proto.Common.V1;
+using Serilog.Events;
 
 namespace Serilog.Sinks.OpenTelemetry;
 
@@ -82,5 +84,11 @@ public enum IncludedData
     /// Preserve the value of the <c>SourceContext</c> property, in addition to using it as the OTLP <c>InstrumentationScope</c> name. If
     /// not specified, the <c>SourceContext</c> property will be omitted from the individual log record attributes.
     /// </summary>
-    SourceContextAttribute = 128
+    SourceContextAttribute = 128,
+    
+    /// <summary>
+    /// Include <see cref="StructureValue.TypeTag"/> as <c>$type</c> when converting event properties to
+    /// OTLP <see cref="AnyValue.KvlistValue"/> values.
+    /// </summary>
+    StructureValueTypeTags = 256,
 }

src/Serilog.Sinks.OpenTelemetry/Sinks/OpenTelemetry/OtlpEventBuilder.cs

@@ -120,7 +120,7 @@ ParentSpanIdPropertyName or
                 continue;
             }
 
-            var v = PrimitiveConversions.ToOpenTelemetryAnyValue(property.Value);
+            var v = PrimitiveConversions.ToOpenTelemetryAnyValue(property.Value, includedData);
             addAttribute(PrimitiveConversions.NewAttribute(property.Key, v));
         }
     }

src/Serilog.Sinks.OpenTelemetry/Sinks/OpenTelemetry/ProtocolHelpers/PrimitiveConversions.cs

@@ -136,7 +136,7 @@ public static AnyValue ToOpenTelemetryScalar(ScalarValue scalar)
         return ToOpenTelemetryPrimitive(scalar.Value);
     }
 
-    public static AnyValue ToOpenTelemetryMap(StructureValue value)
+    public static AnyValue ToOpenTelemetryMap(StructureValue value, IncludedData includedData)
     {
         var map = new AnyValue();
         var kvList = new KeyValueList();
@@ -145,14 +145,27 @@ public static AnyValue ToOpenTelemetryMap(StructureValue value)
         // Per the OTLP protos, attribute keys MUST be unique.
         var seen = new HashSet<string>();
 
+        if ((includedData & IncludedData.StructureValueTypeTags) == IncludedData.StructureValueTypeTags && !string.IsNullOrEmpty(value.TypeTag))
+        {
+            kvList.Values.Add(new KeyValue
+            {
+                Key = "$type",
+                Value = new()
+                {
+                    StringValue = value.TypeTag
+                }
+            });
+        }
+
         foreach (var prop in value.Properties)
         {
-            if (seen.Contains(prop.Name))
+            if (!seen.Add(prop.Name))
+            {
+                // Already present
                 continue;
+            }
 
-            seen.Add(prop.Name);
-
-            var v = ToOpenTelemetryAnyValue(prop.Value);
+            var v = ToOpenTelemetryAnyValue(prop.Value, includedData);
             var kv = new KeyValue
             {
                 Key = prop.Name,
@@ -164,7 +177,7 @@ public static AnyValue ToOpenTelemetryMap(StructureValue value)
         return map;
     }
 
-    public static AnyValue ToOpenTelemetryMap(DictionaryValue value)
+    public static AnyValue ToOpenTelemetryMap(DictionaryValue value, IncludedData includedData)
     {
         var map = new AnyValue();
         var kvList = new KeyValueList();
@@ -173,7 +186,7 @@ public static AnyValue ToOpenTelemetryMap(DictionaryValue value)
         foreach (var element in value.Elements)
         {
             var k = element.Key.Value?.ToString() ?? "null";
-            var v = ToOpenTelemetryAnyValue(element.Value);
+            var v = ToOpenTelemetryAnyValue(element.Value, includedData);
             kvList.Values.Add(new KeyValue
             {
                 Key = k,
@@ -184,27 +197,27 @@ public static AnyValue ToOpenTelemetryMap(DictionaryValue value)
         return map;
     }
 
-    public static AnyValue ToOpenTelemetryArray(SequenceValue value)
+    public static AnyValue ToOpenTelemetryArray(SequenceValue value, IncludedData includedData)
     {
         var array = new AnyValue();
         var values = new ArrayValue();
         array.ArrayValue = values;
         foreach (var element in value.Elements)
         {
-            var v = ToOpenTelemetryAnyValue(element);
+            var v = ToOpenTelemetryAnyValue(element, includedData);
             values.Values.Add(v);
         }
         return array;
     }
 
-    internal static AnyValue ToOpenTelemetryAnyValue(LogEventPropertyValue value)
+    internal static AnyValue ToOpenTelemetryAnyValue(LogEventPropertyValue value, IncludedData includedData)
     {
         return value switch
         {
             ScalarValue scalar => ToOpenTelemetryScalar(scalar),
-            StructureValue structure => ToOpenTelemetryMap(structure),
-            SequenceValue sequence => ToOpenTelemetryArray(sequence),
-            DictionaryValue dictionary => ToOpenTelemetryMap(dictionary),
+            StructureValue structure => ToOpenTelemetryMap(structure, includedData),
+            SequenceValue sequence => ToOpenTelemetryArray(sequence, includedData),
+            DictionaryValue dictionary => ToOpenTelemetryMap(dictionary, includedData),
             _ => ToOpenTelemetryPrimitive(value.ToString()),
         };
     }
@@ -213,7 +226,7 @@ internal static string OnlyHexDigits(string s)
     {
         try
         {
-            return Regex.Replace(s, @"[^0-9a-fA-F]", "", RegexOptions.None, TimeSpan.FromSeconds(1.5));
+            return Regex.Replace(s, "[^0-9a-fA-F]", "", RegexOptions.None, TimeSpan.FromSeconds(1.5));
         }
         catch (RegexMatchTimeoutException)
         {