From 07119c8ff5a2e6ecdde293a82f62ecab97ca0381 Mon Sep 17 00:00:00 2001
From: Sipke Schoorstra <sipkeschoorstra@outlook.com>
Date: Thu, 20 Feb 2025 20:33:55 +0100
Subject: [PATCH] Add OpenTelemetry error span handling infrastructure

Introduce infrastructure for handling error spans with OpenTelemetry, including `DefaultErrorSpanHandler` and `FaultExceptionErrorSpanHandler`. Define core abstractions (`ErrorSpanHandlerBase`, `IErrorSpanHandler`) and utilities for customizing OpenTelemetry integration. This enables improved error tracing and categorization in workflows.
---
 .../Abstractions/ErrorSpanHandlerBase.cs      |  9 +++++++
 .../Contracts/IErrorSpanHandler.cs            | 10 ++++++++
 .../Extensions/ModuleExtensions.cs            | 14 +++++++++++
 .../Handlers/DefaultErrorSpanHandler.cs       | 24 +++++++++++++++++++
 .../FaultExceptionErrorSpanHandler.cs         | 19 +++++++++++++++
 .../Models/ErrorSpanContext.cs                |  9 +++++++
 6 files changed, 85 insertions(+)
 create mode 100644 src/modules/Elsa.OpenTelemetry/Abstractions/ErrorSpanHandlerBase.cs
 create mode 100644 src/modules/Elsa.OpenTelemetry/Contracts/IErrorSpanHandler.cs
 create mode 100644 src/modules/Elsa.OpenTelemetry/Extensions/ModuleExtensions.cs
 create mode 100644 src/modules/Elsa.OpenTelemetry/Handlers/DefaultErrorSpanHandler.cs
 create mode 100644 src/modules/Elsa.OpenTelemetry/Handlers/FaultExceptionErrorSpanHandler.cs
 create mode 100644 src/modules/Elsa.OpenTelemetry/Models/ErrorSpanContext.cs

diff --git a/src/modules/Elsa.OpenTelemetry/Abstractions/ErrorSpanHandlerBase.cs b/src/modules/Elsa.OpenTelemetry/Abstractions/ErrorSpanHandlerBase.cs
new file mode 100644
index 000000000..420936119
--- /dev/null
+++ b/src/modules/Elsa.OpenTelemetry/Abstractions/ErrorSpanHandlerBase.cs
@@ -0,0 +1,9 @@
+using Elsa.OpenTelemetry.Contracts;
+using Elsa.OpenTelemetry.Models;
+
+namespace Elsa.OpenTelemetry.Abstractions;
+
+public abstract class ErrorSpanHandlerBase : IErrorSpanHandler
+{
+    public abstract void Handle(ErrorSpanContext context);
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.OpenTelemetry/Contracts/IErrorSpanHandler.cs b/src/modules/Elsa.OpenTelemetry/Contracts/IErrorSpanHandler.cs
new file mode 100644
index 000000000..d15c3dee4
--- /dev/null
+++ b/src/modules/Elsa.OpenTelemetry/Contracts/IErrorSpanHandler.cs
@@ -0,0 +1,10 @@
+using Elsa.OpenTelemetry.Abstractions;
+using Elsa.OpenTelemetry.Models;
+
+namespace Elsa.OpenTelemetry.Contracts;
+
+public interface IErrorSpanHandler
+{
+    void Handle(ErrorSpanContext context);
+}
+
diff --git a/src/modules/Elsa.OpenTelemetry/Extensions/ModuleExtensions.cs b/src/modules/Elsa.OpenTelemetry/Extensions/ModuleExtensions.cs
new file mode 100644
index 000000000..25edd2794
--- /dev/null
+++ b/src/modules/Elsa.OpenTelemetry/Extensions/ModuleExtensions.cs
@@ -0,0 +1,14 @@
+using Elsa.Features.Services;
+using Elsa.OpenTelemetry.Features;
+
+// ReSharper disable once CheckNamespace
+namespace Elsa.Extensions;
+
+public static class ModuleExtensions
+{
+    public static IModule UseOpenTelemetry(this IModule configuration, Action<OpenTelemetryFeature>? configure = null)
+    {
+        configuration.Configure(configure);
+        return configuration;
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.OpenTelemetry/Handlers/DefaultErrorSpanHandler.cs b/src/modules/Elsa.OpenTelemetry/Handlers/DefaultErrorSpanHandler.cs
new file mode 100644
index 000000000..04bebef62
--- /dev/null
+++ b/src/modules/Elsa.OpenTelemetry/Handlers/DefaultErrorSpanHandler.cs
@@ -0,0 +1,24 @@
+using Elsa.OpenTelemetry.Abstractions;
+using Elsa.OpenTelemetry.Models;
+
+namespace Elsa.OpenTelemetry.Handlers;
+
+public class DefaultErrorSpanHandler : ErrorSpanHandlerBase
+{
+    public override void Handle(ErrorSpanContext context)
+    {
+        var span = context.Span;
+        var exception = context.Exception;
+        var errorMessage = string.IsNullOrWhiteSpace(exception?.Message) ? "Unknown error" : exception.Message;
+        span.SetTag("error", true);
+        span.SetTag("error.message", errorMessage);
+
+        if (exception != null)
+        {
+            span.SetTag("error.exceptionType", exception.GetType().FullName);
+
+            if (!string.IsNullOrEmpty(exception.StackTrace))
+                span.SetTag("error.stackTrace", exception.StackTrace);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.OpenTelemetry/Handlers/FaultExceptionErrorSpanHandler.cs b/src/modules/Elsa.OpenTelemetry/Handlers/FaultExceptionErrorSpanHandler.cs
new file mode 100644
index 000000000..14aa2860a
--- /dev/null
+++ b/src/modules/Elsa.OpenTelemetry/Handlers/FaultExceptionErrorSpanHandler.cs
@@ -0,0 +1,19 @@
+using Elsa.OpenTelemetry.Abstractions;
+using Elsa.OpenTelemetry.Models;
+using Elsa.Workflows.Exceptions;
+
+namespace Elsa.OpenTelemetry.Handlers;
+
+public class FaultExceptionErrorSpanHandler : ErrorSpanHandlerBase
+{
+    public override void Handle(ErrorSpanContext context)
+    {
+        if(context.Exception is not FaultException faultException)
+            return;
+        
+        var span = context.Span;
+        span.SetTag("error.code", faultException.Code);
+        span.SetTag("error.category", faultException.Category);
+        span.SetTag("error.faultType", faultException.Type);
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.OpenTelemetry/Models/ErrorSpanContext.cs b/src/modules/Elsa.OpenTelemetry/Models/ErrorSpanContext.cs
new file mode 100644
index 000000000..a364b1b68
--- /dev/null
+++ b/src/modules/Elsa.OpenTelemetry/Models/ErrorSpanContext.cs
@@ -0,0 +1,9 @@
+using System.Diagnostics;
+
+namespace Elsa.OpenTelemetry.Models;
+
+public class ErrorSpanContext(Activity span, Exception? exception)
+{
+    public Activity Span => span;
+    public Exception? Exception => exception;
+}
\ No newline at end of file