add dependency to ILambdaContext, Powertools Lambda Context fails serialization due to reflection (AOT). Create new converter and use the default one on strings only.

Author: hjgraca

libraries/src/AWS.Lambda.Powertools.Metrics/AWS.Lambda.Powertools.Metrics.csproj

@@ -10,5 +10,13 @@
     <ItemGroup>
         <ProjectReference Include="..\AWS.Lambda.Powertools.Common\AWS.Lambda.Powertools.Common.csproj" PrivateAssets="All" />
     </ItemGroup>
+    
+    <ItemGroup>
+      <Compile Remove="Serializer\StringEnumConverter.cs" />
+    </ItemGroup>
+    
+    <ItemGroup>
+      <PackageReference Include="Amazon.Lambda.Core" />
+    </ItemGroup>
 
 </Project>

libraries/src/AWS.Lambda.Powertools.Metrics/Internal/MetricsAspect.cs

@@ -17,6 +17,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using Amazon.Lambda.Core;
 using AspectInjector.Broker;
 using AWS.Lambda.Powertools.Common;
 
@@ -34,11 +35,6 @@ public class MetricsAspect
     /// </summary>
     private static bool _isColdStart;
 
-    /// <summary>
-    ///     Specify to clear Lambda Context on exit
-    /// </summary>
-    private bool _clearLambdaContext;
-
     /// <summary>
     ///     Gets the metrics instance.
     /// </summary>
@@ -100,14 +96,14 @@ public void Before(
             var nameSpace = _metricsInstance.GetNamespace();
             var service = _metricsInstance.GetService();
             Dictionary<string, string> dimensions = null;
-
-            _clearLambdaContext = PowertoolsLambdaContext.Extract(eventArgs);
-
-            if (PowertoolsLambdaContext.Instance is not null)
+            
+            var context = GetContext(eventArgs);
+            
+            if (context is not null)
             {
                 dimensions = new Dictionary<string, string>
                 {
-                    { "FunctionName", PowertoolsLambdaContext.Instance.FunctionName }
+                    { "FunctionName", context.FunctionName }
                 };
             }
 
@@ -129,8 +125,6 @@ public void Before(
     public void Exit()
     {
         _metricsInstance.Flush();
-        if (_clearLambdaContext)
-            PowertoolsLambdaContext.Clear();
     }
 
 
@@ -142,6 +136,21 @@ internal static void ResetForTest()
         _metricsInstance = null;
         _isColdStart = true;
         Metrics.ResetForTest();
-        PowertoolsLambdaContext.Clear();
+    }
+    
+    /// <summary>
+    /// Gets the Lambda context
+    /// </summary>
+    /// <param name="args"></param>
+    /// <returns></returns>
+    private static ILambdaContext GetContext(AspectEventArgs args)
+    {
+        var index = Array.FindIndex(args.Method.GetParameters(), p => p.ParameterType == typeof(ILambdaContext));
+        if (index >= 0)
+        {
+            return (ILambdaContext)args.Args[index];
+        }
+
+        return null;
     }
 }

libraries/src/AWS.Lambda.Powertools.Metrics/Model/MetricResolution.cs

@@ -1,11 +1,11 @@
-using System.Runtime.Serialization;
 using System.Text.Json.Serialization;
 
 namespace AWS.Lambda.Powertools.Metrics;
 
 /// <summary>
 /// Enum MetricResolution
 /// </summary>
+[JsonConverter(typeof(MetricResolutionJsonConverter))]
 public enum MetricResolution
 {
     /// <summary>

libraries/src/AWS.Lambda.Powertools.Metrics/Model/MetricUnit.cs

@@ -24,7 +24,7 @@ namespace AWS.Lambda.Powertools.Metrics;
 #if NET8_0_OR_GREATER
 [JsonConverter(typeof(JsonStringEnumConverter<MetricUnit>))]
 #else
-[JsonConverter(typeof(StringEnumConverter))]
+[JsonConverter(typeof(JsonStringEnumConverter))]
 #endif
 public enum MetricUnit
 {

libraries/src/AWS.Lambda.Powertools.Metrics/Serializer/MetricResolutionJsonConverter.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace AWS.Lambda.Powertools.Metrics;
+
+/// <summary>
+/// Class MetricResolutionJsonConverter.
+/// Implements the <see cref="System.Text.Json.Serialization.JsonConverter{T}" />
+/// </summary>
+/// <seealso cref="System.Text.Json.Serialization.JsonConverter{T}" />
+public class MetricResolutionJsonConverter : JsonConverter<MetricResolution>
+{
+    /// <summary>
+    /// Reads the JSON representation of the object.
+    /// </summary>
+    /// <param name="reader">The <see cref="T:Utf8JsonReader" /> to read from.</param>
+    /// <param name="typeToConvert">The <see cref="T:System.Type" /> being converted.</param>
+    /// <param name="options">The <see cref="T:Utf8JsonSerializerOptions" /> being used.</param>
+    /// <returns>The object value.</returns>
+    public override MetricResolution Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        switch (reader.TokenType)
+        {
+            case JsonTokenType.String:
+            {
+                string stringValue = reader.GetString();
+                if (int.TryParse(stringValue, out int value))
+                {
+                    return (MetricResolution)value;
+                }
+
+                break;
+            }
+            case JsonTokenType.Number:
+                return (MetricResolution)reader.GetInt32();
+        }
+
+        throw new JsonException();
+    }
+
+    /// <summary>
+    /// Writes the JSON representation of the object.
+    /// </summary>
+    /// <param name="writer">The <see cref="T:Utf8JsonWriter" /> to write to.</param>
+    /// <param name="value">The value to convert.</param>
+    /// <param name="options">The <see cref="T:Utf8JsonSerializerOptions" /> being used.</param>
+    public override void Write(Utf8JsonWriter writer, MetricResolution value, JsonSerializerOptions options)
+    {
+        writer.WriteNumberValue((int)value);
+    }
+}