Merge pull request #613 from hjgraca/fix-metrics-resolution-context

chore: Fix metrics lambda context and storage resolution

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

@@ -11,4 +11,8 @@
         <ProjectReference Include="..\AWS.Lambda.Powertools.Common\AWS.Lambda.Powertools.Common.csproj" PrivateAssets="All" />
     </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 +1,49 @@
+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)
+    {
+        if (reader.TokenType == JsonTokenType.String)
+        {
+            var stringValue = reader.GetString();
+            if (int.TryParse(stringValue, out int value))
+            {
+                return (MetricResolution)value;
+            }
+        }
+        else if (reader.TokenType == 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);
+    }
+}

libraries/tests/AWS.Lambda.Powertools.Metrics.Tests/Handlers/FunctionHandler.cs

@@ -169,8 +169,14 @@ public void HandleWithLambdaContext(ILambdaContext context)
     }
 
     [Metrics(Namespace = "ns", Service = "svc")]
-    public void HandleWithLambdaContextAndMetrics(TestLambdaContext context)
+    public void HandleColdStartNoContext()
     {
         Metrics.AddMetric("MyMetric", 1);
     }
+
+    [Metrics(Namespace = "ns", Service = "svc", CaptureColdStart = true)]
+    public void HandleWithParamAndLambdaContext(string input, ILambdaContext context)
+    {
+
+    }
 }

libraries/tests/AWS.Lambda.Powertools.Metrics.Tests/Handlers/FunctionHandlerTests.cs

@@ -88,6 +88,46 @@ public void When_LambdaContext_Should_Add_FunctioName_Dimension_CaptureColdStart
             "\"Metrics\":[{\"Name\":\"ColdStart\",\"Unit\":\"Count\"}],\"Dimensions\":[[\"FunctionName\"],[\"Service\"]]}]}",
             metricsOutput);
     }
+
+    [Fact]
+    public void When_LambdaContext_And_Parameter_Should_Add_FunctioName_Dimension_CaptureColdStart()
+    {
+        // Arrange
+        var context = new TestLambdaContext
+        {
+            FunctionName = "My Function with context"
+        };
+
+        // Act
+        _handler.HandleWithParamAndLambdaContext("Hello",context);
+        var metricsOutput = _consoleOut.ToString();
+
+        // Assert
+        Assert.Contains(
+            "\"FunctionName\":\"My Function with context\"",
+            metricsOutput);
+
+        Assert.Contains(
+            "\"Metrics\":[{\"Name\":\"ColdStart\",\"Unit\":\"Count\"}],\"Dimensions\":[[\"FunctionName\"],[\"Service\"]]}]}",
+            metricsOutput);
+    }
+
+    [Fact]
+    public void When_No_LambdaContext_Should_Not_Add_FunctioName_Dimension_CaptureColdStart()
+    {
+        // Act
+        _handler.HandleColdStartNoContext();
+        var metricsOutput = _consoleOut.ToString();
+
+        // Assert
+        Assert.DoesNotContain(
+            "\"FunctionName\"",
+            metricsOutput);
+
+        Assert.Contains(
+            "\"Metrics\":[{\"Name\":\"MyMetric\",\"Unit\":\"None\"}],\"Dimensions\":[[\"Service\"]]}]},\"Service\":\"svc\",\"MyMetric\":1}",
+            metricsOutput);
+    }
 
     public void Dispose()
     {