#1571 Add annotations support for executable assemblies

Docs/lambda-annotations-design.md

@@ -330,7 +330,69 @@ public class LambdaFunctions
 }
 ```
 
+## Auto Generate Main
 
+A `LambdaGlobalProperties` attribute is available to set global settings that annotations framework uses when generated code at compile time. This simplifies the programming model when using custom runtimes or native ahead of time (AOT) compilation. It removes the need to manually bootstrap the Lambda runtime.
+
+To auto-generate the `static Main` method, first ensure the `OutputType` in your `csproj` file is set to `exe`.
+```xml
+<PropertyGroup>
+    <!--Removed for brevity..-->
+    <OutputType>exe</OutputType>
+</PropertyGroup>
+```
+
+Once the output type is set to executable, add the `LambdaGlobalProperties` assembly attribute and set the `GenerateMain` property to true. You can also configure the `Runtime` in the generated CloudFormation template.
+
+```c#
+[assembly: LambdaGlobalProperties(GenerateMain = true, Runtime = "provided.al2")]
+```
+
+### Behind The Scenes
+
+Assuming the below Lambda function handler:
+
+```c#
+public class Greeter
+{
+    [LambdaFunction(ResourceName = "GreeterSayHello", MemorySize = 1024, PackageType = LambdaPackageType.Image)]
+    [HttpApi(LambdaHttpMethod.Get, "/Greeter/SayHello", Version = HttpApiVersion.V1)]
+    public void SayHello([FromQuery(Name = "names")]IEnumerable<string> firstNames, APIGatewayProxyRequest request, ILambdaContext context)
+    {
+        context.Logger.LogLine($"Request {JsonSerializer.Serialize(request)}");
+
+        if (firstNames == null)
+        {
+            return;
+        }
+
+        foreach (var firstName in firstNames)
+        {
+            Console.WriteLine($"Hello {firstName}");
+        }
+    }
+}
+```
+
+The generated `static Main` method would look like the below. To allow for multiple Lambda functions in the same executable an Environment variable is used to determine which handler is executed. When using the `GenerateMain` attribute, ensure you also set the `ANNOTATIONS_HANDLER` environment variable on the deployed resource.
+
+The auto-generated CloudFormation template will include this as a default. 
+
+```c#
+public class GeneratedProgram
+{
+    private static async Task Main(string[] args)
+    {
+        switch (Environment.GetEnvironmentVariable("ANNOTATIONS_HANDLER"))
+        {
+            case "ToUpper":
+                Func<string, string> toupper_handler = new TestServerlessApp.Sub1.Functions_ToUpper_Generated().ToUpper;
+                await Amazon.Lambda.RuntimeSupport.LambdaBootstrapBuilder.Create(toupper_handler, new Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer()).Build().RunAsync();
+                break;
+        }
+    }
+}
+```
 
 ## Lambda .NET Attributes
 
@@ -368,3 +430,9 @@ Here is a preliminary list of .NET attributes that will tell the source generato
     * Map method parameter to HTTP request body. If parameter is a complex type then request body will be assumed to be JSON and deserialized into the type.
 * FromServices
     * Map method parameter to registered service in IServiceProvider
+
+### Global Attributes    
+* GenerateMain
+    * Generates a `static Program` class and a `static Main` method that bootstraps the Lambda runtime. Simplifies the programming model when building on a custom runtime or using native ahead of time (AOT) compilation.
+* Runtime
+    * Set the runtime in the generated CloudFormation template. Set to either `dotnet6` or `provided.al2`

Libraries/Amazon.Lambda.Annotations.slnf

@@ -2,13 +2,15 @@
   "solution": {
     "path": "Libraries.sln",
     "projects": [
-      "src\\Amazon.Lambda.APIGatewayEvents\\Amazon.Lambda.APIGatewayEvents.csproj",
       "src\\Amazon.Lambda.Annotations.SourceGenerator\\Amazon.Lambda.Annotations.SourceGenerator.csproj",
       "src\\Amazon.Lambda.Annotations\\Amazon.Lambda.Annotations.csproj",
+      "src\\Amazon.Lambda.APIGatewayEvents\\Amazon.Lambda.APIGatewayEvents.csproj",
+      "src\\Amazon.Lambda.RuntimeSupport\\Amazon.Lambda.RuntimeSupport.csproj",
       "src\\Amazon.Lambda.Core\\Amazon.Lambda.Core.csproj",
       "src\\Amazon.Lambda.Serialization.SystemTextJson\\Amazon.Lambda.Serialization.SystemTextJson.csproj",
       "test\\Amazon.Lambda.Annotations.SourceGenerators.Tests\\Amazon.Lambda.Annotations.SourceGenerators.Tests.csproj",
       "test\\TestServerlessApp.IntegrationTests\\TestServerlessApp.IntegrationTests.csproj",
+      "test\\TestExecutableServerlessApp\\TestExecutableServerlessApp.csproj",
       "test\\TestServerlessApp\\TestServerlessApp.csproj"
     ]
   }

Libraries/Libraries.sln

@@ -130,6 +130,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Amazon.Lambda.LexV2Events",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CustomRuntimeAspNetCoreMinimalApiCustomSerializerTest", "test\Amazon.Lambda.RuntimeSupport.Tests\CustomRuntimeAspNetCoreMinimalApiCustomSerializerTest\CustomRuntimeAspNetCoreMinimalApiCustomSerializerTest.csproj", "{0BD83939-458C-4EF5-8663-7098AD1200F2}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestExecutableServerlessApp", "test\TestExecutableServerlessApp\TestExecutableServerlessApp.csproj", "{DD378063-C54A-44C7-9A6F-32A6A1AE94B3}"
+EndProject
 Global
 	GlobalSection(SharedMSBuildProjectFiles) = preSolution
 		test\EventsTests.Shared\EventsTests.Shared.projitems*{44e9d925-b61d-4234-97b7-61424c963ba6}*SharedItemsImports = 5
@@ -353,6 +355,10 @@ Global
 		{0BD83939-458C-4EF5-8663-7098AD1200F2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{0BD83939-458C-4EF5-8663-7098AD1200F2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{0BD83939-458C-4EF5-8663-7098AD1200F2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DD378063-C54A-44C7-9A6F-32A6A1AE94B3}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DD378063-C54A-44C7-9A6F-32A6A1AE94B3}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DD378063-C54A-44C7-9A6F-32A6A1AE94B3}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DD378063-C54A-44C7-9A6F-32A6A1AE94B3}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -415,6 +421,7 @@ Global
 		{BF85932E-2DFF-41CD-8090-A672468B8FBB} = {AAB54E74-20B1-42ED-BC3D-CE9F7BC7FD12}
 		{3C6AABF5-0372-41E0-874F-DF18ECCC7FB6} = {AAB54E74-20B1-42ED-BC3D-CE9F7BC7FD12}
 		{0BD83939-458C-4EF5-8663-7098AD1200F2} = {B5BD0336-7D08-492C-8489-42C987E29B39}
+		{DD378063-C54A-44C7-9A6F-32A6A1AE94B3} = {1DE4EE60-45BA-4EF7-BE00-B9EB861E4C69}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {503678A4-B8D1-4486-8915-405A3E9CF0EB}

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Amazon.Lambda.Annotations.SourceGenerator.csproj

@@ -56,6 +56,10 @@
       <Generator>TextTemplatingFilePreprocessor</Generator>
       <LastGenOutput>NoEventMethodBody.cs</LastGenOutput>
     </None>
+    <None Update="Templates\ExecutableAssembly.tt">
+      <Generator>TextTemplatingFilePreprocessor</Generator>
+      <LastGenOutput>ExecutableAssembly.cs</LastGenOutput>
+    </None>
   </ItemGroup>
 
   <ItemGroup>
@@ -84,6 +88,11 @@
       <AutoGen>True</AutoGen>
       <DependentUpon>NoEventMethodBody.tt</DependentUpon>
     </Compile>
+    <Compile Update="Templates\ExecutableAssembly.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>ExecutableAssembly.tt</DependentUpon>
+    </Compile>
   </ItemGroup>
 
   <ItemGroup>

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs

@@ -44,6 +44,20 @@ public static class DiagnosticDescriptors
             category: "AWSLambdaCSharpGenerator",
             DiagnosticSeverity.Error,
             isEnabledByDefault: true);
+
+        public static readonly DiagnosticDescriptor ExecutableWithNoFunctions = new DiagnosticDescriptor(id: "AWSLambda0104",
+            title: "Executable output with no LambdaFunction annotations",
+            messageFormat: "Your project is configured to output an executable and generate a static Main method, but you have not configured any methods with the 'LambdaFunction' attribute.",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
+
+        public static readonly DiagnosticDescriptor MainMethodExists = new DiagnosticDescriptor(id: "AWSLambda0104",
+            title: "static Main method exists",
+            messageFormat: "Failed to generate Main method for LambdaGenerateMainAttribute because project already contains Main method. Existing Main methods must be removed when using LambdaGenerateMainAttribute attribute.",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
 
         public static readonly DiagnosticDescriptor HttpResultsOnNonApiFunction = new DiagnosticDescriptor(id: "AWSLambda0105",
             title: $"Invalid return type {nameof(IHttpResult)}",
@@ -87,5 +101,21 @@ public static class DiagnosticDescriptors
            category: "AWSLambdaCSharpGenerator",
            DiagnosticSeverity.Error,
            isEnabledByDefault: true);
+
+        public static readonly DiagnosticDescriptor SetOutputTypeExecutable = new DiagnosticDescriptor(id: "AWSLambda0111",
+            title: "Output Type is not an executable",
+            messageFormat: "AssemblyAttribute Amazon.Lambda.Annotations.LambdaGlobalPropertiesAttribute is configured to generate a static main method " + 
+                           "but the assembly itself is not configured to output an executable. Set the 'OutputType' property in the .csproj file to be 'exe'.",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
+
+        public static readonly DiagnosticDescriptor InvalidRuntimeSelection = new DiagnosticDescriptor(id: "AWSLambda0112",
+            title: "Invalid runtime selection",
+            messageFormat: "The runtime selected in the Amazon.Lambda.Annotations.LambdaGlobalPropertiesAttribute is not a supported value " + 
+                           "It should be set to either 'dotnet6' or 'provided.al2'.",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
     }
 }