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Add [ScheduleEvent] annotation attribute and source generator support
- ScheduleEventAttribute with Schedule (rate/cron), ResourceName, Description, Input, Enabled - ScheduleEventAttributeBuilder for Roslyn AttributeData parsing - Source generator wiring (TypeFullNames, SyntaxReceiver, EventTypeBuilder, AttributeModelBuilder) - CloudFormationWriter ProcessScheduleAttribute (SAM Schedule event rule) - LambdaFunctionValidator ValidateScheduleEvents - DiagnosticDescriptors InvalidScheduleEventAttribute - ScheduleEventAttributeTests (attribute unit tests) - ScheduleEventsTests (CloudFormation writer tests) - E2E source generator snapshot tests - Integration test (ScheduleEventRule) - Sample function (ScheduledProcessing) - .autover change file - README documentation
1 parent e06cfdd commit b1c1d26

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+1002
-3
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‎.autover/changes/add-scheduleevent-annotation.json‎

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@@ -0,0 +1,11 @@
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{
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"Projects": [
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{
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"Name": "Amazon.Lambda.Annotations",
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"Type": "Minor",
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"ChangelogMessages": [
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"Added [ScheduleEvent] annotation attribute for declaratively configuring schedule-triggered Lambda functions with support for rate and cron expressions, description, input, and enabled state."
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]
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}
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]
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}

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

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@@ -281,5 +281,12 @@ public static class DiagnosticDescriptors
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category: "AWSLambdaCSharpGenerator",
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DiagnosticSeverity.Error,
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isEnabledByDefault: true);
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public static readonly DiagnosticDescriptor InvalidScheduleEventAttribute = new DiagnosticDescriptor(id: "AWSLambda0132",
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title: "Invalid ScheduleEventAttribute",
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messageFormat: "Invalid ScheduleEventAttribute encountered: {0}",
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category: "AWSLambdaCSharpGenerator",
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DiagnosticSeverity.Error,
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isEnabledByDefault: true);
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}
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}

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/Attributes/AttributeModelBuilder.cs‎

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@@ -1,5 +1,6 @@
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using System;
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using Amazon.Lambda.Annotations.ALB;
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using Amazon.Lambda.Annotations.Schedule;
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using Amazon.Lambda.Annotations.APIGateway;
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using Amazon.Lambda.Annotations.S3;
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using Amazon.Lambda.Annotations.SQS;
@@ -101,6 +102,15 @@ public static AttributeModel Build(AttributeData att, GeneratorExecutionContext
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Type = TypeModelBuilder.Build(att.AttributeClass, context)
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};
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}
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else if (att.AttributeClass.Equals(context.Compilation.GetTypeByMetadataName(TypeFullNames.ScheduleEventAttribute), SymbolEqualityComparer.Default))
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{
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var data = ScheduleEventAttributeBuilder.Build(att);
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model = new AttributeModel<ScheduleEventAttribute>
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{
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Data = data,
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Type = TypeModelBuilder.Build(att.AttributeClass, context)
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};
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}
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else if (att.AttributeClass.Equals(context.Compilation.GetTypeByMetadataName(TypeFullNames.HttpApiAuthorizerAttribute), SymbolEqualityComparer.Default))
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{
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var data = HttpApiAuthorizerAttributeBuilder.Build(att);

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/Attributes/ScheduleEventAttributeBuilder.cs‎

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using Amazon.Lambda.Annotations.Schedule;
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using Microsoft.CodeAnalysis;
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using System;
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namespace Amazon.Lambda.Annotations.SourceGenerator.Models.Attributes
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{
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/// <summary>
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/// Builder for <see cref="ScheduleEventAttribute"/>.
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/// </summary>
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public class ScheduleEventAttributeBuilder
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{
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public static ScheduleEventAttribute Build(AttributeData att)
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{
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if (att.ConstructorArguments.Length != 1)
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{
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throw new NotSupportedException($"{TypeFullNames.ScheduleEventAttribute} must have constructor with 1 argument.");
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}
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var schedule = att.ConstructorArguments[0].Value as string;
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var data = new ScheduleEventAttribute(schedule);
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foreach (var pair in att.NamedArguments)
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{
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if (pair.Key == nameof(data.ResourceName) && pair.Value.Value is string resourceName)
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{
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data.ResourceName = resourceName;
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}
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else if (pair.Key == nameof(data.Description) && pair.Value.Value is string description)
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{
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data.Description = description;
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}
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else if (pair.Key == nameof(data.Input) && pair.Value.Value is string input)
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{
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data.Input = input;
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}
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else if (pair.Key == nameof(data.Enabled) && pair.Value.Value is bool enabled)
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{
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data.Enabled = enabled;
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}
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}
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return data;
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}
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}
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}

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/EventTypeBuilder.cs‎

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@@ -30,6 +30,10 @@ public static HashSet<EventType> Build(IMethodSymbol lambdaMethodSymbol,
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{
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events.Add(EventType.S3);
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}
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else if (attribute.AttributeClass.ToDisplayString() == TypeFullNames.ScheduleEventAttribute)
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{
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events.Add(EventType.Schedule);
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}
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else if (attribute.AttributeClass.ToDisplayString() == TypeFullNames.HttpApiAuthorizerAttribute
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|| attribute.AttributeClass.ToDisplayString() == TypeFullNames.RestApiAuthorizerAttribute)
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{

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/SyntaxReceiver.cs‎

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@@ -23,7 +23,8 @@ internal class SyntaxReceiver : ISyntaxContextReceiver
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{ "RestApiAttribute", "RestApi" },
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{ "SQSEventAttribute", "SQSEvent" },
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{ "ALBApiAttribute", "ALBApi" },
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{ "S3EventAttribute", "S3Event" }
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{ "S3EventAttribute", "S3Event" },
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{ "ScheduleEventAttribute", "ScheduleEvent" }
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};
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public List<MethodDeclarationSyntax> LambdaMethods { get; } = new List<MethodDeclarationSyntax>();

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/TypeFullNames.cs‎

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@@ -56,6 +56,9 @@ public static class TypeFullNames
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public const string S3Event = "Amazon.Lambda.S3Events.S3Event";
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public const string S3EventAttribute = "Amazon.Lambda.Annotations.S3.S3EventAttribute";
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public const string ScheduledEvent = "Amazon.Lambda.CloudWatchEvents.ScheduledEvents.ScheduledEvent";
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public const string ScheduleEventAttribute = "Amazon.Lambda.Annotations.Schedule.ScheduleEventAttribute";
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public const string LambdaSerializerAttribute = "Amazon.Lambda.Core.LambdaSerializerAttribute";
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public const string DefaultLambdaSerializer = "Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer";
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@@ -84,7 +87,8 @@ public static class TypeFullNames
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HttpApiAttribute,
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SQSEventAttribute,
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ALBApiAttribute,
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S3EventAttribute
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S3EventAttribute,
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ScheduleEventAttribute
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};
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}
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}

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Validation/LambdaFunctionValidator.cs‎

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using Amazon.Lambda.Annotations.SourceGenerator.Extensions;
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using Amazon.Lambda.Annotations.SourceGenerator.Models;
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using Amazon.Lambda.Annotations.SourceGenerator.Models.Attributes;
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using Amazon.Lambda.Annotations.Schedule;
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using Amazon.Lambda.Annotations.SQS;
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using Microsoft.CodeAnalysis;
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using System.Collections.Generic;
@@ -61,6 +62,7 @@ internal static bool ValidateFunction(GeneratorExecutionContext context, IMethod
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// Validate Events
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ValidateApiGatewayEvents(lambdaFunctionModel, methodLocation, diagnostics);
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ValidateSqsEvents(lambdaFunctionModel, methodLocation, diagnostics);
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ValidateScheduleEvents(lambdaFunctionModel, methodLocation, diagnostics);
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ValidateAlbEvents(lambdaFunctionModel, methodLocation, diagnostics);
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ValidateS3Events(lambdaFunctionModel, methodLocation, diagnostics);
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}
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}
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// Check for references to "Amazon.Lambda.CloudWatchEvents" if the Lambda method is annotated with ScheduleEvent attribute.
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if (lambdaMethodSymbol.HasAttribute(context, TypeFullNames.ScheduleEventAttribute))
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{
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if (context.Compilation.ReferencedAssemblyNames.FirstOrDefault(x => x.Name == "Amazon.Lambda.CloudWatchEvents") == null)
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{
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diagnosticReporter.Report(Diagnostic.Create(DiagnosticDescriptors.MissingDependencies, methodLocation, "Amazon.Lambda.CloudWatchEvents"));
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return false;
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}
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}
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return true;
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}
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}
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}
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private static void ValidateScheduleEvents(LambdaFunctionModel lambdaFunctionModel, Location methodLocation, List<Diagnostic> diagnostics)
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{
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if (!lambdaFunctionModel.LambdaMethod.Events.Contains(EventType.Schedule))
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{
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return;
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}
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foreach (var att in lambdaFunctionModel.Attributes)
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{
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if (att.Type.FullName != TypeFullNames.ScheduleEventAttribute)
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continue;
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var scheduleEventAttribute = ((AttributeModel<ScheduleEventAttribute>)att).Data;
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var validationErrors = scheduleEventAttribute.Validate();
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validationErrors.ForEach(errorMessage => diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.InvalidScheduleEventAttribute, methodLocation, errorMessage)));
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}
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// Validate method parameters
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var parameters = lambdaFunctionModel.LambdaMethod.Parameters;
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if (parameters.Count > 2 ||
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(parameters.Count >= 1 && parameters[0].Type.FullName != TypeFullNames.ScheduledEvent) ||
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(parameters.Count == 2 && parameters[1].Type.FullName != TypeFullNames.ILambdaContext))
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{
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var errorMessage = $"When using the {nameof(ScheduleEventAttribute)}, the Lambda method can accept at most 2 parameters. " +
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$"The first parameter must be of type {TypeFullNames.ScheduledEvent}. " +
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$"The second parameter is optional and must be of type {TypeFullNames.ILambdaContext}.";
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diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.InvalidLambdaMethodSignature, methodLocation, errorMessage));
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}
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// Validate return type - must be void or Task
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if (!lambdaFunctionModel.LambdaMethod.ReturnsVoid && !lambdaFunctionModel.LambdaMethod.ReturnsVoidTask)
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{
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var errorMessage = $"When using the {nameof(ScheduleEventAttribute)}, the Lambda method can return either void or {TypeFullNames.Task}";
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diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.InvalidLambdaMethodSignature, methodLocation, errorMessage));
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}
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}
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private static bool ReportDiagnostics(DiagnosticReporter diagnosticReporter, List<Diagnostic> diagnostics)
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{
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var isValid = true;

‎Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Writers/CloudFormationWriter.cs‎

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using Amazon.Lambda.Annotations.SourceGenerator.Diagnostics;
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using Amazon.Lambda.Annotations.SourceGenerator.FileIO;
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using Amazon.Lambda.Annotations.SourceGenerator.Models;
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using Amazon.Lambda.Annotations.Schedule;
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using Amazon.Lambda.Annotations.SourceGenerator.Models.Attributes;
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using Amazon.Lambda.Annotations.S3;
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using Amazon.Lambda.Annotations.SQS;
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eventName = ProcessS3Attribute(lambdaFunction, s3AttributeModel.Data, currentSyncedEventProperties);
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currentSyncedEvents.Add(eventName);
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break;
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case AttributeModel<ScheduleEventAttribute> scheduleAttributeModel:
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eventName = ProcessScheduleAttribute(lambdaFunction, scheduleAttributeModel.Data, currentSyncedEventProperties);
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currentSyncedEvents.Add(eventName);
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break;
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}
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}
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return att.ResourceName;
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}
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/// <summary>
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/// Writes all properties associated with <see cref="ScheduleEventAttribute"/> to the serverless template.
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/// </summary>
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private string ProcessScheduleAttribute(ILambdaFunctionSerializable lambdaFunction, ScheduleEventAttribute att, Dictionary<string, List<string>> syncedEventProperties)
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{
621+
var eventName = att.ResourceName;
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var eventPath = $"Resources.{lambdaFunction.ResourceName}.Properties.Events.{eventName}";
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_templateWriter.SetToken($"{eventPath}.Type", "Schedule");
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// Schedule expression
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SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "Schedule", att.Schedule);
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// Description
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if (att.IsDescriptionSet)
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{
632+
SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "Description", att.Description);
633+
}
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// Input
636+
if (att.IsInputSet)
637+
{
638+
SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "Input", att.Input);
639+
}
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// Enabled
642+
if (att.IsEnabledSet)
643+
{
644+
SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "Enabled", att.Enabled);
645+
}
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647+
return att.ResourceName;
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}
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/// <summary>
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/// Writes all properties associated with <see cref="S3EventAttribute"/> to the serverless template.
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/// </summary>

‎Libraries/src/Amazon.Lambda.Annotations/README.md‎

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- [Amazon API Gateway example](#amazon-api-gateway-example)
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- [Amazon S3 example](#amazon-s3-example)
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- [SQS Event Example](#sqs-event-example)
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- [Schedule Event Example](#schedule-event-example)
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- [Application Load Balancer (ALB) Example](#application-load-balancer-alb-example)
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- [Custom Lambda Authorizer Example](#custom-lambda-authorizer-example)
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- [HTTP API Authorizer](#http-api-authorizer)
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Then your Lambda function references `@MyListener` in the `ALBApi` attribute.
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## Schedule Event Example
1078+
This example shows how to use the `ScheduleEvent` attribute to trigger a Lambda function on a schedule using EventBridge.
1079+
1080+
The `ScheduleEvent` attribute contains the following properties:
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* **Schedule** (Required) - The schedule expression. Supports `rate()` and `cron()` expressions (e.g. `rate(5 minutes)`, `cron(0 12 * * ? *)`).
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* **ResourceName** (Optional) - The CloudFormation resource name for the schedule event.
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* **Description** (Optional) - A description for the schedule rule.
1084+
* **Input** (Optional) - A JSON string to pass as input to the Lambda function.
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* **Enabled** (Optional) - If false, the schedule rule is disabled. Default is true.
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1087+
```csharp
1088+
[LambdaFunction(ResourceName = "ScheduledHandler", Policies = "AWSLambdaBasicExecutionRole")]
1089+
[ScheduleEvent("rate(5 minutes)", ResourceName = "FiveMinuteSchedule", Description = "Runs every 5 minutes")]
1090+
public void HandleSchedule(ScheduledEvent evnt, ILambdaContext lambdaContext)
1091+
{
1092+
lambdaContext.Logger.Log($"Scheduled event received at {evnt.Time}");
1093+
}
1094+
```
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## Custom Lambda Authorizer Example
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10781098
Lambda Annotations supports defining custom Lambda authorizers using attributes. Custom authorizers let you control access to your API Gateway endpoints by running a Lambda function that validates tokens or request parameters before the target function is invoked. The source generator automatically wires up the authorizer resources and references in the CloudFormation template.
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* Marks a Lambda function as a REST API (API Gateway V1) custom authorizer. The authorizer name is automatically derived from the method name. Other functions reference it via `RestApi.Authorizer` using `nameof()`. Use the `Type` property to choose between `Token` and `Request` authorizer types.
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* SQSEvent
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* Sets up event source mapping between the Lambda function and SQS queues. The SQS queue ARN is required to be set on the attribute. If users want to pass a reference to an existing SQS queue resource defined in their CloudFormation template, they can pass the SQS queue resource name prefixed with the '@' symbol.
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* ScheduleEvent
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* Triggers the Lambda function on a schedule using EventBridge. Supports rate and cron expressions.
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* ALBApi
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* Configures the Lambda function to be called from an Application Load Balancer. The listener ARN (or `@ResourceName` template reference), path pattern, and priority are required. The source generator creates standalone CloudFormation resources (TargetGroup, ListenerRule, Lambda Permission) rather than SAM event types.
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