Handle both stream optimized and api gateway optimized

Author: reakaleek

Directory.Packages.props

@@ -12,6 +12,7 @@
   </ItemGroup>
   <!-- AWS -->
   <ItemGroup>
+    <PackageVersion Include="Amazon.Lambda.APIGatewayEvents" Version="2.7.1" />
     <PackageVersion Include="Amazon.Lambda.AspNetCoreServer.Hosting" Version="1.9.0" />
     <PackageVersion Include="Amazon.Lambda.RuntimeSupport" Version="1.13.4" />
     <PackageVersion Include="Amazon.Lambda.Core" Version="2.7.1" />

src/api/Elastic.Documentation.Api.Lambda/Elastic.Documentation.Api.Lambda.csproj

@@ -27,6 +27,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Amazon.Lambda.AspNetCoreServer.Hosting"/>
     <PackageReference Include="Elastic.OpenTelemetry" />
     <PackageReference Include="OpenTelemetry.Instrumentation.AspNetCore" />
   </ItemGroup>

src/api/Elastic.Documentation.Api.Lambda/Program.cs

@@ -2,9 +2,13 @@
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
 
+using System.Text.Json.Serialization;
+using Amazon.Lambda.APIGatewayEvents;
+using Amazon.Lambda.Serialization.SystemTextJson;
+using Elastic.Documentation.Api.Core.AskAi;
+using Elastic.Documentation.Api.Core.Search;
 using Elastic.Documentation.Api.Infrastructure;
 using Elastic.Documentation.ServiceDefaults;
-using Microsoft.Extensions.Logging;
 using OpenTelemetry;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
@@ -48,12 +52,24 @@
 	process.Refresh();
 	Console.WriteLine($"Elastic OTel configured. Memory: {process.WorkingSet64 / 1024 / 1024} MB");
 
-	// Configure Kestrel to listen on port 8080 for Lambda Web Adapter
-	// Lambda Web Adapter expects the app to run as a standard HTTP server on localhost:8080
-	_ = builder.WebHost.ConfigureKestrel(serverOptions =>
+	// If we are running in Lambda Web Adapter response_stream mode, configure Kestrel to listen on port 8080
+	// Otherwise, configure AWS Lambda hosting for API Gateway HTTP API
+	if (Environment.GetEnvironmentVariable("AWS_LWA_INVOKE_MODE") == "response_stream")
 	{
-		serverOptions.ListenLocalhost(8080);
-	});
+		// Configure Kestrel to listen on port 8080 for Lambda Web Adapter
+		// Lambda Web Adapter expects the app to run as a standard HTTP server on localhost:8080
+		_ = builder.WebHost.ConfigureKestrel(serverOptions =>
+		{
+			serverOptions.ListenLocalhost(8080);
+		});
+	}
+	else
+	{
+		// Configure AWS Lambda hosting with custom JSON serializer context for API Gateway HTTP API
+		_ = builder.Services.AddAWSLambdaHosting(LambdaEventSource.HttpApi, new SourceGeneratorLambdaJsonSerializer<LambdaJsonSerializerContext>());
+		_ = builder.WebHost.UseKestrelHttpsConfiguration();
+	}
+
 	process.Refresh();
 	Console.WriteLine($"Kestrel configured to listen on port 8080. Memory: {process.WorkingSet64 / 1024 / 1024} MB");
 
@@ -82,3 +98,10 @@
 	Console.WriteLine($"Stack trace: {ex.StackTrace}");
 	throw;
 }
+
+[JsonSerializable(typeof(APIGatewayHttpApiV2ProxyRequest))]
+[JsonSerializable(typeof(APIGatewayHttpApiV2ProxyResponse))]
+[JsonSerializable(typeof(AskAiRequest))]
+[JsonSerializable(typeof(SearchRequest))]
+[JsonSerializable(typeof(SearchResponse))]
+internal sealed partial class LambdaJsonSerializerContext : JsonSerializerContext;