Expose ITextFormatter to RenderMessage in Serilog (#449)

src/Elastic.CommonSchema.Serilog/EcsTextFormatterConfiguration.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using Elastic.CommonSchema.Serilog.Adapters;
 using Serilog.Events;
 
@@ -32,6 +33,11 @@ public interface IEcsTextFormatterConfiguration : IEcsDocumentCreationOptions
 		/// Stop certain keys to be persisted as <see cref="EcsDocument.Metadata"/> or <see cref="BaseFieldSet.Labels"/>
 		/// </summary>
 		ISet<string>? LogEventPropertiesToFilter { get;set; }
+
+		/// <summary>
+		/// Provide a <see cref="IFormatProvider"/> to <see cref="LogEvent.RenderMessage(System.IO.TextWriter,System.IFormatProvider)"/>
+		/// </summary>
+		IFormatProvider? MessageFormatProvider { get; set; }
 	}
 
 	/// <summary> Provides configuration options for <see cref="EcsTextFormatter{TEcsDocument}"/> </summary>
@@ -66,6 +72,9 @@ public class EcsTextFormatterConfiguration<TEcsDocument> : IEcsTextFormatterConf
 		/// <inheritdoc cref="IEcsTextFormatterConfiguration.LogEventPropertiesToFilter"/>
 		public ISet<string>? LogEventPropertiesToFilter { get; set; }
 
+		/// <inheritdoc cref="IEcsTextFormatterConfiguration.MessageFormatProvider"/>
+		public IFormatProvider? MessageFormatProvider { get; set; }
+
 		/// <inheritdoc cref="IEcsTextFormatterConfiguration{TEcsDocument}.MapCustom"/>
 		public Func<TEcsDocument, LogEvent, TEcsDocument>? MapCustom { get; set; }
 	}

src/Elastic.CommonSchema.Serilog/LogEventConverter.cs

@@ -49,7 +49,7 @@ public static TEcsDocument ConvertToEcs<TEcsDocument>(LogEvent logEvent, IEcsTex
 			var user = GetUser(logEvent, configuration);
 			if (user != null) ecsEvent.User = user;
 
-			ecsEvent.Message = logEvent.RenderMessage();
+			ecsEvent.Message = logEvent.RenderMessage(configuration.MessageFormatProvider);
 			ecsEvent.Log = GetLog(logEvent);
 			ecsEvent.Agent = GetAgent(logEvent) ?? DefaultAgent;
 			ecsEvent.Event = GetEvent(logEvent);