Add trace context fields in ElasticsearchLogger (#115)

This commit adds trace context fields to log events
when using ElasticsearchLogger.

The trace context fields are extracted from the current
System.Diagnostics.Activity if not null. When the Id
format used is W3C, the Activity.TraceId and Activity.SpanId
will be used to set Trace.Id and Span.Id, respectively. For
any other id format, Trace.Id and Span.Id will be set from
Activity.RootId and Activity.Id, respectively. When there
is no current Activity but CorrelationManager has an
ActivityId, this will be used for the Trace.Id.

Co-authored-by: Russ Cam <[email protected]>

Author: sgryphon

src/Elasticsearch.Extensions.Logging/ElasticsearchLogger.cs

@@ -129,16 +129,25 @@ private void AddTracing(LogEvent logEvent)
 
 			if (activity != null)
 			{
-				// Unique identifier of the trace.
-				// A trace groups multiple events like transactions that belong together. For example, a user request handled by multiple inter-connected services.
-				logEvent.Trace = new Trace() { Id = activity.RootId };
+				if (activity.IdFormat == ActivityIdFormat.W3C)
+				{
+					// Unique identifier of the trace.
+					// A trace groups multiple events like transactions that belong together. For example, a user request handled by multiple inter-connected services.
+					logEvent.Trace = new Trace { Id = activity.TraceId.ToString() };
+					logEvent.Span = new Span { Id = activity.SpanId.ToString() };
+				}
+				else
+				{
+					if (activity.RootId != null) logEvent.Trace = new Trace { Id = activity.RootId };
+					if (activity.Id != null) logEvent.Span = new Span { Id = activity.Id };
+				}
 			}
 			else
 			{
 				if (!System.Diagnostics.Trace.CorrelationManager.ActivityId.Equals(Guid.Empty))
 				{
 					logEvent.Trace =
-						new Trace() { Id = System.Diagnostics.Trace.CorrelationManager.ActivityId.ToString() };
+						new Trace { Id = System.Diagnostics.Trace.CorrelationManager.ActivityId.ToString() };
 				}
 			}
 		}
@@ -157,7 +166,6 @@ Func<TState, Exception, string> formatter
 				Event = new Event { Action = eventId.Name, Code = eventId.Id.ToString(), Severity = LogEventToEcsHelper.GetSeverity(logLevel) }
 			};
 
-
 			if (exception != null) AddException(exception, logEvent);
 
 			logEvent.Agent = LogEventToEcsHelper.GetAgent();
@@ -189,13 +197,24 @@ Func<TState, Exception, string> formatter
 
 		private bool CheckTracingValues(LogEvent logEvent, KeyValuePair<string, object> kvp)
 		{
-			if (kvp.Key == "trace.id")
+			if (kvp.Key == "span.id")
 			{
 				var value = FormatValue(kvp.Value);
 				if (!string.IsNullOrWhiteSpace(value))
 				{
-					if (logEvent.Trace == null) logEvent.Trace = new Trace();
+					logEvent.Span ??= new Span();
+					logEvent.Span.Id = value;
+				}
 
+				return true;
+			}
+
+			if (kvp.Key == "trace.id")
+			{
+				var value = FormatValue(kvp.Value);
+				if (!string.IsNullOrWhiteSpace(value))
+				{
+					logEvent.Trace ??= new Trace();
 					logEvent.Trace.Id = value;
 				}
 
@@ -207,8 +226,7 @@ private bool CheckTracingValues(LogEvent logEvent, KeyValuePair<string, object>
 				var value = FormatValue(kvp.Value);
 				if (!string.IsNullOrWhiteSpace(value))
 				{
-					if (logEvent.Transaction == null) logEvent.Transaction = new Transaction();
-
+					logEvent.Transaction ??= new Transaction();
 					logEvent.Transaction.Id = value;
 				}
 

src/Elasticsearch.Extensions.Logging/LogEvent.cs

@@ -17,7 +17,8 @@ public class LogEvent : Base
 		private const string ScopesPropertyName = nameof(Scopes);
 
 		/// <summary>
-		/// Custom field with the original message template, e.g. "Unexpected error processing customer {CustomerId}."
+		/// Custom field with the original template used to generate the message, with token placeholders
+		/// for inserted label values, e.g. "Unexpected error processing customer {CustomerId}."
 		/// </summary>
 		[DataMember(Name = MessageTemplatePropertyName)]
 		public string? MessageTemplate { get; set; }