[Logs Bridge API] Add support for Body set directly on LogRecord for OTLP Exporter.

src/OpenTelemetry.Exporter.InMemory/AssemblyInfo.cs

@@ -0,0 +1,20 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#if !EXPOSE_EXPERIMENTAL_FEATURES
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests" + AssemblyInfo.PublicKey)]
+#endif
+
+#if SIGNED
+file static class AssemblyInfo
+{
+    public const string PublicKey = ", PublicKey=002400000480000094000000060200000024000052534131000400000100010051C1562A090FB0C9F391012A32198B5E5D9A60E9B80FA2D7B434C9E5CCB7259BD606E66F9660676AFC6692B8CDC6793D190904551D2103B7B22FA636DCBB8208839785BA402EA08FC00C8F1500CCEF28BBF599AA64FFB1E1D5DC1BF3420A3777BADFE697856E9D52070A50C3EA5821C80BEF17CA3ACFFA28F89DD413F096F898";
+}
+#else
+file static class AssemblyInfo
+{
+    public const string PublicKey = "";
+}
+#endif

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/CHANGELOG.md

@@ -15,6 +15,12 @@
   will be automatically included in exports.
   ([#5258](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5258))
 
+* Updated `OtlpLogExporter` to set `body` on the data model from
+  `LogRecord.Body` if `{OriginalFormat}` attribute is NOT found and
+  `FormattedMessage` is `null`. This is typically the case when using the
+  experimental Logs Bridge API.
+  ([#5268](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5268))
+
 ## 1.7.0
 
 Released 2023-Dec-08

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

@@ -170,6 +170,14 @@ internal OtlpLogs.LogRecord ToOtlpLog(LogRecord logRecord)
                         AddAttribute(otlpLogRecord, result, attributeCountLimit);
                     }
                 }
+
+                // Supports setting Body directly on LogRecord for the Logs Bridge API.
+                if (otlpLogRecord.Body == null && logRecord.Body != null)
+                {
+                    // If {OriginalFormat} is not present in the attributes,
+                    // use logRecord.Body if it is set.
+                    otlpLogRecord.Body = new OtlpCommon.AnyValue { StringValue = logRecord.Body };
+                }
             }
 
             if (logRecord.TraceId != default && logRecord.SpanId != default)

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

@@ -589,6 +589,63 @@ public void CheckToOtlpLogRecordBodyIsPopulated(bool includeFormattedMessage)
         Assert.Equal("state", otlpLogRecord.Body.StringValue);
     }
 
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public void LogRecordBodyIsExportedWhenUsingBridgeApi(bool isBodySet)
+    {
+        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 = isBodySet ? "Hello world" : null,
+            });
+
+            logger.EmitLog(new LogRecordData(), attributes);
+        }
+
+        Assert.Equal(2, logRecords.Count);
+
+        var otlpLogRecordTransformer = new OtlpLogRecordTransformer(DefaultSdkLimitOptions, new());
+
+        var otlpLogRecord = otlpLogRecordTransformer.ToOtlpLog(logRecords[0]);
+
+        if (isBodySet)
+        {
+            Assert.Equal("Hello world", otlpLogRecord.Body?.StringValue);
+        }
+        else
+        {
+            Assert.Null(otlpLogRecord.Body);
+        }
+
+        otlpLogRecord = otlpLogRecordTransformer.ToOtlpLog(logRecords[1]);
+
+        Assert.Equal(2, otlpLogRecord.Attributes.Count);
+
+        var index = 0;
+        var attribute = otlpLogRecord.Attributes[index];
+        Assert.Equal("name", attribute.Key);
+        Assert.Equal("tomato", attribute.Value.StringValue);
+
+        attribute = otlpLogRecord.Attributes[++index];
+        Assert.Equal("price", attribute.Key);
+        Assert.Equal(2.99, attribute.Value.DoubleValue);
+
+        Assert.Equal("Hello from {name} {price}.", otlpLogRecord.Body.StringValue);
+    }
+
     [Fact]
     public void CheckToOtlpLogRecordExceptionAttributes()
     {