feat: add event metadata property

serilog/MetadataTextFormatter.cs

@@ -0,0 +1,155 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using Serilog.Debugging;
+using Serilog.Events;
+using Serilog.Formatting;
+using Serilog.Formatting.Json;
+using Serilog.Parsing;
+
+namespace SerilogExample
+{
+    public class MetadataTextFormatter : ITextFormatter
+    {
+        private static readonly JsonValueFormatter ValueFormatter = new JsonValueFormatter();
+
+        /// <summary>
+        /// Format the log event into the output.
+        /// </summary>
+        /// <param name="logEvent">The event to format.</param>
+        /// <param name="output">The output.</param>
+        public void Format(LogEvent logEvent, TextWriter output)
+        {
+            try
+            {
+                var buffer = new StringWriter();
+                FormatContent(logEvent, buffer);
+
+                // If formatting was successful, write to output
+                output.WriteLine(buffer.ToString());
+            }
+            catch (Exception e)
+            {
+                LogNonFormattableEvent(logEvent, e);
+            }
+        }
+
+        private void FormatContent(LogEvent logEvent, TextWriter output)
+        {
+            if (logEvent == null) throw new ArgumentNullException(nameof(logEvent));
+            if (output == null) throw new ArgumentNullException(nameof(output));
+
+            output.Write("{\"Timestamp\":\"");
+            output.Write(logEvent.Timestamp.ToString("o"));
+
+            output.Write("\",\"Level\":\"");
+            output.Write(logEvent.Level);
+
+            output.Write("\",\"MessageTemplate\":");
+            JsonValueFormatter.WriteQuotedJsonString(logEvent.MessageTemplate.Text, output);
+
+            output.Write(",\"RenderedMessage\":");
+
+            var message = logEvent.MessageTemplate.Render(logEvent.Properties);
+            JsonValueFormatter.WriteQuotedJsonString(message, output);
+
+            if (logEvent.Exception != null)
+            {
+                output.Write(",\"Exception\":");
+                JsonValueFormatter.WriteQuotedJsonString(logEvent.Exception.ToString(), output);
+            }
+
+            if (logEvent.Properties.Count != 0)
+            {
+                WriteProperties(logEvent.Properties, output);
+            }
+
+            // Better not to allocate an array in the 99.9% of cases where this is false
+            var tokensWithFormat = logEvent.MessageTemplate.Tokens
+                .OfType<PropertyToken>()
+                .Where(pt => pt.Format != null);
+
+            // ReSharper disable once PossibleMultipleEnumeration
+            if (tokensWithFormat.Any())
+            {
+                // ReSharper disable once PossibleMultipleEnumeration
+                WriteRenderings(tokensWithFormat.GroupBy(pt => pt.PropertyName), logEvent.Properties, output);
+            }
+
+            // Add a @metadata property that will be used by Logstash to separate logs from
+            // multiple applications
+            output.Write(", \"@metadata\":{\"app\":\"my-app\",\"version\":\"1.2.3\"}");
+
+            output.Write('}');
+        }
+
+        private static void WriteProperties(
+            IReadOnlyDictionary<string, LogEventPropertyValue> properties,
+            TextWriter output)
+        {
+            output.Write(",\"Properties\":{");
+
+            var precedingDelimiter = "";
+
+            foreach (var property in properties)
+            {
+                output.Write(precedingDelimiter);
+                precedingDelimiter = ",";
+
+                JsonValueFormatter.WriteQuotedJsonString(property.Key, output);
+                output.Write(':');
+                ValueFormatter.Format(property.Value, output);
+            }
+
+            output.Write('}');
+        }
+
+        private static void WriteRenderings(
+            IEnumerable<IGrouping<string, PropertyToken>> tokensWithFormat,
+            IReadOnlyDictionary<string, LogEventPropertyValue> properties,
+            TextWriter output)
+        {
+            output.Write(",\"Renderings\":{");
+
+            var rdelim = "";
+            foreach (var ptoken in tokensWithFormat)
+            {
+                output.Write(rdelim);
+                rdelim = ",";
+
+                JsonValueFormatter.WriteQuotedJsonString(ptoken.Key, output);
+                output.Write(":[");
+
+                var fdelim = "";
+                foreach (var format in ptoken)
+                {
+                    output.Write(fdelim);
+                    fdelim = ",";
+
+                    output.Write("{\"Format\":");
+                    JsonValueFormatter.WriteQuotedJsonString(format.Format, output);
+
+                    output.Write(",\"Rendering\":");
+                    var sw = new StringWriter();
+                    format.Render(properties, sw);
+                    JsonValueFormatter.WriteQuotedJsonString(sw.ToString(), output);
+                    output.Write('}');
+                }
+
+                output.Write(']');
+            }
+
+            output.Write('}');
+        }
+
+        private static void LogNonFormattableEvent(LogEvent logEvent, Exception e)
+        {
+            SelfLog.WriteLine(
+                "Event at {0} with message template {1} could not be formatted into JSON and will be dropped: {2}",
+                logEvent.Timestamp.ToString("o"),
+                logEvent.MessageTemplate.Text,
+                e);
+        }
+    }
+}

serilog/Program.cs

@@ -12,8 +12,9 @@ public class Program
         static void Main()
         {
             ILogger logger = new LoggerConfiguration()
-                .WriteTo.DurableHttpUsingFileSizeRolledBuffers(
+                .WriteTo.Http(
                     requestUri: "http://logstash:31311",
+                    textFormatter: new MetadataTextFormatter(),
                     batchFormatter: new ArrayBatchFormatter())
                 .WriteTo.Console()
                 .CreateLogger()
@@ -26,9 +27,9 @@ static void Main()
             {
                 var customer = customerGenerator.Generate();
                 var order = orderGenerator.Generate();
-                
+
                 logger.Information("{@customer} placed {@order}", customer, order);
-                
+
                 Thread.Sleep(1000);
             }
         }

serilog/serilog-example.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp5.0</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Bogus" Version="32.0.2" />