feat(logs): add log4net integration

samples/Sentry.Samples.Log4Net/Program.cs

@@ -11,7 +11,7 @@ internal class Program
     private static void Main()
     {
         // Set the user running the process the current principal
-        // Appender was configure to send the user with the event
+        // Appender was configured to send the user with the event
         AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);
 
         // The following anonymous object gets serialized and sent with log messages

samples/Sentry.Samples.Log4Net/Sentry.Samples.Log4Net.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net10.0</TargetFramework>
+    <TargetFramework>net481</TargetFramework>
     <Version>3.5.234</Version>
   </PropertyGroup>
 

src/Sentry.Log4Net/LevelMapping.cs

@@ -29,4 +29,20 @@ internal static class LevelMapping
             _ => null
         };
     }
+
+    public static SentryLogLevel? ToSentryLogLevel(this LoggingEvent loggingEvent)
+    {
+        return loggingEvent.Level switch
+        {
+            var level when level == Level.Off => null,
+            var level when level >= Level.Fatal => SentryLogLevel.Fatal,
+            var level when level >= Level.Error => SentryLogLevel.Error,
+            var level when level >= Level.Warn => SentryLogLevel.Warning,
+            var level when level >= Level.Info => SentryLogLevel.Info,
+            var level when level >= Level.Debug => SentryLogLevel.Debug,
+            var level when level >= Level.Trace => SentryLogLevel.Trace,
+            var level when level >= Level.All => SentryLogLevel.Trace,
+            _ => null,
+        };
+    }
 }

src/Sentry.Log4Net/Sentry.Log4Net.csproj

@@ -26,4 +26,10 @@
     <InternalsVisibleTo Include="Sentry.Log4Net.Tests" PublicKey="$(SentryPublicKey)" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Update="SentryAppender.Structured.cs">
+      <DependentUpon>SentryAppender.cs</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
 </Project>

src/Sentry.Log4Net/SentryAppender.Structured.cs

@@ -0,0 +1,46 @@
+namespace Sentry.Log4Net;
+
+public partial class SentryAppender
+{
+    private static void CaptureStructuredLog(IHub hub, SentryOptions options, LoggingEvent loggingEvent)
+    {
+        if (loggingEvent.ToSentryLogLevel() is not { } level)
+        {
+            return;
+        }
+
+        DateTimeOffset timestamp = new(loggingEvent.TimeStampUtc);
+        const string? template = null; // cannot get format-string from `log4net.Util.SystemStringFormat` via `LoggingEvent.MessageObject`
+        var parameters = ImmutableArray<KeyValuePair<string, object>>.Empty; // cannot get arguments from `log4net.Util.SystemStringFormat` via `LoggingEvent.MessageObject`
+
+        var message = !string.IsNullOrWhiteSpace(loggingEvent.RenderedMessage) ? loggingEvent.RenderedMessage : string.Empty;
+        var log = SentryLog.Create(hub, timestamp, level, message, template, parameters);
+
+        var scope = hub.GetScope();
+        log.SetDefaultAttributes(options, scope, Sdk);
+        log.SetOrigin("auto.log.log4net");
+
+        if (loggingEvent.LoggerName is { } loggerName)
+        {
+            log.SetAttribute("category.name", loggerName);
+        }
+
+        // GetProperties() is non-null in current log4net, but the sibling GetLoggingEventProperties guards
+        // against null, so we do too rather than rely on log4net's internals.
+        if (loggingEvent.GetProperties() is { } properties)
+        {
+            foreach (var property in properties)
+            {
+                if (property is DictionaryEntry { Key: string key, Value: { } value })
+                {
+                    if (key.Length != 0 && !key.StartsWith("log4net:", StringComparison.OrdinalIgnoreCase) && !Guid.TryParse(key, out _))
+                    {
+                        log.SetAttribute($"property.{key}", value);
+                    }
+                }
+            }
+        }
+
+        hub.Logger.CaptureLog(log);
+    }
+}

src/Sentry.Log4Net/SentryAppender.cs

@@ -5,7 +5,7 @@
 /// <summary>
 /// Sentry appender for log4net.
 /// </summary>
-public class SentryAppender : AppenderSkeleton
+public partial class SentryAppender : AppenderSkeleton
 {
     private readonly Func<string, IDisposable> _initAction;
     private volatile IDisposable? _sdkHandle;
@@ -15,6 +15,12 @@
     internal static readonly SdkVersion NameAndVersion
         = typeof(SentryAppender).Assembly.GetNameAndVersion();
 
+    private static readonly SdkVersion Sdk = new()
+    {
+        Name = SdkName,
+        Version = NameAndVersion.Version,
+    };
+
     private static readonly string ProtocolPackageName = "nuget:" + NameAndVersion.Name;
 
     private readonly IHub _hub;
@@ -88,17 +94,30 @@
 
         if (MinimumEventLevel is not null && loggingEvent.Level < MinimumEventLevel)
         {
-            var message = !string.IsNullOrWhiteSpace(loggingEvent.RenderedMessage) ? loggingEvent.RenderedMessage : string.Empty;
-            var category = loggingEvent.LoggerName;
-            var level = loggingEvent.ToBreadcrumbLevel();
-            IDictionary<string, string> data = GetLoggingEventProperties(loggingEvent)
-                .Where(kvp => kvp.Value != null)
-                .ToDictionary(kvp => kvp.Key, kvp => kvp.Value!.ToString() ?? "");
+            AddBreadcrumbFromLoggingEvent(loggingEvent);
+            return;
+        }
 
-            _hub.AddBreadcrumb(message, category, type: null, data, level ?? default);
+        CreateSentryEvent(loggingEvent, exception);
+
+        var options = _hub.GetSentryOptions();
+        if (options is not { EnableLogs: true })
+        {
             return;
         }
 
+        try
+        {
+            CaptureStructuredLog(_hub, options, loggingEvent);
+        }
+        catch (Exception ex)
+        {
+            options.DiagnosticLogger?.LogError(ex, "Failed to capture structured log. The log will be dropped.");
+        }
+    }
+
+    private void CreateSentryEvent(LoggingEvent loggingEvent, Exception? exception)
+    {
         var evt = new SentryEvent(exception)
         {
             Logger = loggingEvent.LoggerName,
@@ -139,6 +158,19 @@
         _hub.CaptureEvent(evt);
     }
 
+    private void AddBreadcrumbFromLoggingEvent(LoggingEvent loggingEvent)
+    {
+        var message = !string.IsNullOrWhiteSpace(loggingEvent.RenderedMessage) ? loggingEvent.RenderedMessage : string.Empty;
+        var category = loggingEvent.LoggerName;
+        var level = loggingEvent.ToBreadcrumbLevel();
+        IDictionary<string, string> data = GetLoggingEventProperties(loggingEvent)
+            .Where(kvp => kvp.Value != null)
+            .ToDictionary(kvp => kvp.Key, kvp => kvp.Value!.ToString() ?? "");
+
+        _hub.AddBreadcrumb(message, category, type: null, data, level ?? default);
+        return;
+    }
+
     private static IEnumerable<KeyValuePair<string, object?>> GetLoggingEventProperties(LoggingEvent loggingEvent)
     {
         var properties = loggingEvent.GetProperties();

src/Sentry/SentryLog.cs

@@ -27,6 +27,20 @@ internal SentryLog(DateTimeOffset timestamp, SentryId traceId, SentryLogLevel le
         Parameters = ImmutableArray<KeyValuePair<string, object>>.Empty;
     }
 
+    internal static SentryLog Create(IHub hub, DateTimeOffset timestamp, SentryLogLevel level, string message, string? template, ImmutableArray<KeyValuePair<string, object>> parameters)
+    {
+        hub.GetTraceIdAndSpanId(out var traceId, out var spanId);
+
+        SentryLog log = new(timestamp, traceId, level, message)
+        {
+            Template = template,
+            Parameters = parameters,
+            SpanId = spanId,
+        };
+
+        return log;
+    }
+
     /// <summary>
     /// The timestamp of the log.
     /// </summary>

test/Sentry.Log4Net.Tests/Sentry.Log4Net.Tests.csproj

@@ -19,4 +19,10 @@
     <Using Include="Sentry.Log4Net" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Update="SentryAppenderTests.Structured.cs">
+      <DependentUpon>SentryAppenderTests.cs</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
 </Project>