Adding EventName to LogRecord (#6306)

Co-authored-by: Alan West <[email protected]>

Author: juliuskoval

src/OpenTelemetry.Api/.publicApi/Experimental/PublicAPI.Unshipped.txt

@@ -41,6 +41,8 @@ OpenTelemetry.Logs.LogRecordData.TraceFlags.get -> System.Diagnostics.ActivityTr
 OpenTelemetry.Logs.LogRecordData.TraceFlags.set -> void
 OpenTelemetry.Logs.LogRecordData.TraceId.get -> System.Diagnostics.ActivityTraceId
 OpenTelemetry.Logs.LogRecordData.TraceId.set -> void
+OpenTelemetry.Logs.LogRecordData.EventName.get -> string?
+OpenTelemetry.Logs.LogRecordData.EventName.set -> void
 OpenTelemetry.Logs.LogRecordSeverity
 OpenTelemetry.Logs.LogRecordSeverity.Debug = 5 -> OpenTelemetry.Logs.LogRecordSeverity
 OpenTelemetry.Logs.LogRecordSeverity.Debug2 = 6 -> OpenTelemetry.Logs.LogRecordSeverity

src/OpenTelemetry.Api/CHANGELOG.md

@@ -10,6 +10,10 @@ Notes](../../RELEASENOTES.md).
   linking spans and associating optional attributes for advanced trace relationships.
   ([#6305](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6305))
 
+* Experimental (only in pre-release versions): Added the `EventName` property
+  to `LogRecordData`
+  ([#6306](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6306))
+
 ## 1.12.0
 
 Released 2025-Apr-29

src/OpenTelemetry.Api/Logs/LogRecordData.cs

@@ -125,6 +125,11 @@ public DateTime Timestamp
     /// </summary>
     public string? Body { get; set; } = null;
 
+    /// <summary>
+    /// Gets or sets the name of the event associated with the log.
+    /// </summary>
+    public string? EventName { get; set; } = null;
+
     internal static void SetActivityContext(ref LogRecordData data, Activity? activity)
     {
         if (activity != null)

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/CHANGELOG.md

@@ -12,6 +12,13 @@ Notes](../../RELEASENOTES.md).
   write position, resulting in gRPC protocol errors.
   ([#6280](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6280))
 
+* If `EventName` is specified either through `ILogger` or the experimental
+  log bridge API, it is exported as `EventName` by default instead of
+  `logrecord.event.name` which was previously behind the
+  `OTEL_DOTNET_EXPERIMENTAL_OTLP_EMIT_EVENT_LOG_ATTRIBUTES` feature flag.
+  Note that exporting `logrecord.event.id` is still behind that same feature
+  flag. ([#6306](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6306))
+
 ## 1.12.0
 
 Released 2025-Apr-29

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExperimentalOptions.cs

@@ -9,8 +9,6 @@ internal sealed class ExperimentalOptions
 {
     public const string LogRecordEventIdAttribute = "logrecord.event.id";
 
-    public const string LogRecordEventNameAttribute = "logrecord.event.name";
-
     public const string EmitLogEventEnvVar = "OTEL_DOTNET_EXPERIMENTAL_OTLP_EMIT_EVENT_LOG_ATTRIBUTES";
 
     public const string OtlpRetryEnvVar = "OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY";

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/Serializer/ProtobufOtlpLogFieldNumberConstants.cs

@@ -36,6 +36,7 @@ internal static class ProtobufOtlpLogFieldNumberConstants
     internal const int LogRecord_Flags = 8;
     internal const int LogRecord_Trace_Id = 9;
     internal const int LogRecord_Span_Id = 10;
+    internal const int LogRecord_Event_Name = 12;
 
     // SeverityNumber
     internal const int Severity_Number_Unspecified = 0;

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/Serializer/ProtobufOtlpLogSerializer.cs

@@ -192,11 +192,6 @@ internal static int WriteLogRecord(byte[] buffer, int writePosition, SdkLimitOpt
             {
                 AddLogAttribute(state, ExperimentalOptions.LogRecordEventIdAttribute, logRecord.EventId.Id);
             }
-
-            if (!string.IsNullOrEmpty(logRecord.EventId.Name))
-            {
-                AddLogAttribute(state, ExperimentalOptions.LogRecordEventNameAttribute, logRecord.EventId.Name!);
-            }
         }
 
         if (logRecord.Exception != null)
@@ -254,6 +249,11 @@ internal static int WriteLogRecord(byte[] buffer, int writePosition, SdkLimitOpt
             otlpTagWriterState.WritePosition = ProtobufSerializer.WriteFixed32WithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Flags, (uint)logRecord.TraceFlags);
         }
 
+        if (logRecord.EventId.Name != null)
+        {
+            otlpTagWriterState.WritePosition = ProtobufSerializer.WriteStringWithTag(otlpTagWriterState.Buffer, otlpTagWriterState.WritePosition, ProtobufOtlpLogFieldNumberConstants.LogRecord_Event_Name, logRecord.EventId.Name!);
+        }
+
         logRecord.ForEachScope(ProcessScope, state);
 
         if (otlpTagWriterState.DroppedTagCount > 0)

src/OpenTelemetry/Logs/LoggerSdk.cs

@@ -1,6 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+using Microsoft.Extensions.Logging;
 using OpenTelemetry.Internal;
 
 namespace OpenTelemetry.Logs;
@@ -35,6 +36,7 @@ public override void EmitLog(in LogRecordData data, in LogRecordAttributeList at
 
             logRecord.Data = data;
             logRecord.ILoggerData = default;
+            logRecord.ILoggerData.EventId = new EventId(default, data.EventName);
 
             logRecord.Logger = this;
 

src/Shared/Proto/opentelemetry/proto/logs/v1/logs.proto

@@ -221,7 +221,5 @@ message LogRecord {
   // as an event.
   //
   // [Optional].
-  //
-  // Status: [Development]
   string event_name = 12;
-}
+}

test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/OtlpLogExporterTests.cs

@@ -342,19 +342,18 @@ public void CheckToOtlpLogRecordEventId(string? emitLogEventAttributes)
         Assert.NotNull(otlpLogRecord);
         Assert.Equal("Hello from tomato 2.99.", otlpLogRecord.Body.StringValue);
 
+        Assert.Equal("MyEvent10", otlpLogRecord.EventName);
+
         // Event
         otlpLogRecordAttributes = otlpLogRecord.Attributes.ToString();
         if (emitLogEventAttributes == "true")
         {
             Assert.Contains(ExperimentalOptions.LogRecordEventIdAttribute, otlpLogRecordAttributes, StringComparison.Ordinal);
             Assert.Contains("10", otlpLogRecordAttributes, StringComparison.Ordinal);
-            Assert.Contains(ExperimentalOptions.LogRecordEventNameAttribute, otlpLogRecordAttributes, StringComparison.Ordinal);
-            Assert.Contains("MyEvent10", otlpLogRecordAttributes, StringComparison.Ordinal);
         }
         else
         {
             Assert.DoesNotContain(ExperimentalOptions.LogRecordEventIdAttribute, otlpLogRecordAttributes, StringComparison.Ordinal);
-            Assert.DoesNotContain(ExperimentalOptions.LogRecordEventNameAttribute, otlpLogRecordAttributes, StringComparison.Ordinal);
         }
     }
 
@@ -1478,6 +1477,49 @@ public void LogRecordLoggerNameIsExportedWhenUsingBridgeApi(string? loggerName,
         Assert.Equal(expectedScopeName, request.ResourceLogs[0].ScopeLogs[0].Scope?.Name);
     }
 
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public void LogRecordEventNameIsExportedWhenUsingBridgeApi(bool emitEventName)
+    {
+        LogRecordAttributeList attributes = default;
+        attributes.Add("name", "tomato");
+        attributes.Add("price", 2.99);
+        attributes.Add("{OriginalFormat}", "Hello from {name} {price}.");
+
+        var logRecords = new List<LogRecord>();
+
+        using (var loggerProvider = Sdk.CreateLoggerProviderBuilder()
+                   .AddInMemoryExporter(logRecords)
+                   .Build())
+        {
+            var logger = loggerProvider.GetLogger();
+
+            logger.EmitLog(new LogRecordData
+            {
+                Body = "test body",
+                EventName = emitEventName ? "test event" : null,
+            });
+        }
+
+        Assert.Single(logRecords);
+        var logRecord = logRecords[0];
+
+        OtlpLogs.LogRecord? otlpLogRecord = ToOtlpLogs(DefaultSdkLimitOptions, new ExperimentalOptions(), logRecord);
+
+        Assert.NotNull(otlpLogRecord);
+        Assert.Equal("test body", otlpLogRecord.Body.StringValue);
+
+        if (!emitEventName)
+        {
+            Assert.Empty(otlpLogRecord.EventName);
+        }
+        else
+        {
+            Assert.Equal("test event", otlpLogRecord.EventName);
+        }
+    }
+
     [Fact]
     public void LogSerialization_ExpandsBufferForLogsAndSerializes()
     {