added a Java example for an API Gateway with proxy resources to HTTP backend APIs

java/http-proxy-apigateway/.gitignore

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+.classpath.txt
+target
+.classpath
+.project
+.idea
+.settings
+.vscode
+*.iml
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out
+

java/http-proxy-apigateway/README.md

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+# HTTP Proxy APIGateway
+
+<!--BEGIN STABILITY BANNER-->
+
+---
+![Stability: Stable](https://img.shields.io/badge/stability-Stable-success.svg?style=for-the-badge)
+> **This is a stable example. It should successfully build out of the box**
+>
+> This example is built on Construct Libraries marked "Stable" and does not have any infrastructure prerequisites to build.
+---
+
+<!--END STABILITY BANNER-->
+
+This example creates an API Gateway with proxy resources for 2 HTTP backends.
+This is useful for scenarios when incoming requests must be routed to one or more backend API hosts.
+An HTTP proxy integration enables direct interactions between clients and backends without any intervention from the API Gateway after the API method is set up.
+
+> For more information on using HTTP proxy integrations with the APIGateway check out this [AWS tutorial](https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-create-api-as-simple-proxy-for-http.html).
+
+> For demonstration purposes this CDK example deploys a solution that routes to a couple of test HTTP APIs.
+> The 2 test HTTP APIs are implemented using lambdas exposed through function URLs.
+> This example can be modified though, if you prefer to use your own HTTP backend APIs.
+> To do that you can modify the `createHTTPTestAPIs` method in the [`HttpProxyApiGatewayStack`](src/main/java/com/myorg/HttpProxyApiGatewayStack.java) class to return a list of `ProxyResourceParameters` corresponding to your own resources.
+
+## Build
+
+To build this example, you need to be in this example's root directory. Then run the following:
+
+```bash
+  npm install -g aws-cdk
+  npm install
+  cdk synth
+```
+
+This will install the necessary CDK, then this example's dependencies, and then build the CloudFormation template. The resulting CloudFormation template will be in the `cdk.out` directory.
+
+## Deploy
+
+Run `cdk deploy`.
+This will deploy / redeploy the Stack to AWS.
+After the CDK deployment is successful, 2 URL examples will be available in the terminal console:
+
+- One for the `HttpProxyApiGatewayStack.HelloFunctionResourceExample` output
+- One for the `HttpProxyApiGatewayStack.ByeFunctionResourceExample` output
+
+At this point, you can copy each of the 2 URLs and paste them in the address bar of a browser to invoke the 2 APIs.
+Also note that both URLs have the same host (the DNS of the new API Gateway created).
+
+## Useful commands
+
+* `mvn package`     compile and run tests
+* `cdk ls`          list all stacks in the app
+* `cdk synth`       emits the synthesized CloudFormation template
+* `cdk deploy`      deploy this stack to your default AWS account/region
+* `cdk diff`        compare deployed stack with current state
+* `cdk docs`        open CDK documentation

java/http-proxy-apigateway/cdk.json

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+{
+  "app": "mvn -e -q compile exec:java",
+  "watch": {
+    "include": [
+      "**"
+    ],
+    "exclude": [
+      "README.md",
+      "cdk*.json",
+      "target",
+      "pom.xml",
+      "src/test"
+    ]
+  },
+  "context": {
+    "@aws-cdk/aws-lambda:recognizeLayerVersion": true,
+    "@aws-cdk/core:checkSecretUsage": true,
+    "@aws-cdk/core:target-partitions": [
+      "aws",
+      "aws-cn"
+    ],
+    "@aws-cdk-containers/ecs-service-extensions:enableDefaultLogDriver": true,
+    "@aws-cdk/aws-ec2:uniqueImdsv2TemplateName": true,
+    "@aws-cdk/aws-ecs:arnFormatIncludesClusterName": true,
+    "@aws-cdk/aws-iam:minimizePolicies": true,
+    "@aws-cdk/core:validateSnapshotRemovalPolicy": true,
+    "@aws-cdk/aws-codepipeline:crossAccountKeyAliasStackSafeResourceName": true,
+    "@aws-cdk/aws-s3:createDefaultLoggingPolicy": true,
+    "@aws-cdk/aws-sns-subscriptions:restrictSqsDescryption": true,
+    "@aws-cdk/aws-apigateway:disableCloudWatchRole": true,
+    "@aws-cdk/core:enablePartitionLiterals": true,
+    "@aws-cdk/aws-events:eventsTargetQueueSameAccount": true,
+    "@aws-cdk/aws-ecs:disableExplicitDeploymentControllerForCircuitBreaker": true,
+    "@aws-cdk/aws-iam:importedRoleStackSafeDefaultPolicyName": true,
+    "@aws-cdk/aws-s3:serverAccessLogsUseBucketPolicy": true,
+    "@aws-cdk/aws-route53-patters:useCertificate": true,
+    "@aws-cdk/customresources:installLatestAwsSdkDefault": false,
+    "@aws-cdk/aws-rds:databaseProxyUniqueResourceName": true,
+    "@aws-cdk/aws-codedeploy:removeAlarmsFromDeploymentGroup": true,
+    "@aws-cdk/aws-apigateway:authorizerChangeDeploymentLogicalId": true,
+    "@aws-cdk/aws-ec2:launchTemplateDefaultUserData": true,
+    "@aws-cdk/aws-secretsmanager:useAttachedSecretResourcePolicyForSecretTargetAttachments": true,
+    "@aws-cdk/aws-redshift:columnId": true,
+    "@aws-cdk/aws-stepfunctions-tasks:enableEmrServicePolicyV2": true,
+    "@aws-cdk/aws-ec2:restrictDefaultSecurityGroup": true,
+    "@aws-cdk/aws-apigateway:requestValidatorUniqueId": true,
+    "@aws-cdk/aws-kms:aliasNameRef": true,
+    "@aws-cdk/aws-autoscaling:generateLaunchTemplateInsteadOfLaunchConfig": true,
+    "@aws-cdk/core:includePrefixInUniqueNameGeneration": true,
+    "@aws-cdk/aws-efs:denyAnonymousAccess": true,
+    "@aws-cdk/aws-opensearchservice:enableOpensearchMultiAzWithStandby": true,
+    "@aws-cdk/aws-lambda-nodejs:useLatestRuntimeVersion": true,
+    "@aws-cdk/aws-efs:mountTargetOrderInsensitiveLogicalId": true,
+    "@aws-cdk/aws-rds:auroraClusterChangeScopeOfInstanceParameterGroupWithEachParameters": true,
+    "@aws-cdk/aws-appsync:useArnForSourceApiAssociationIdentifier": true,
+    "@aws-cdk/aws-rds:preventRenderingDeprecatedCredentials": true,
+    "@aws-cdk/aws-codepipeline-actions:useNewDefaultBranchForCodeCommitSource": true,
+    "@aws-cdk/aws-cloudwatch-actions:changeLambdaPermissionLogicalIdForLambdaAction": true,
+    "@aws-cdk/aws-codepipeline:crossAccountKeysDefaultValueToFalse": true,
+    "@aws-cdk/aws-codepipeline:defaultPipelineTypeToV2": true,
+    "@aws-cdk/aws-kms:reduceCrossAccountRegionPolicyScope": true,
+    "@aws-cdk/aws-eks:nodegroupNameAttribute": true,
+    "@aws-cdk/aws-ec2:ebsDefaultGp3Volume": true,
+    "@aws-cdk/aws-ecs:removeDefaultDeploymentAlarm": true,
+    "@aws-cdk/custom-resources:logApiResponseDataPropertyTrueDefault": false,
+    "@aws-cdk/aws-s3:keepNotificationInImportedBucket": false,
+    "@aws-cdk/aws-ecs:reduceEc2FargateCloudWatchPermissions": true,
+    "@aws-cdk/aws-dynamodb:resourcePolicyPerReplica": true,
+    "@aws-cdk/aws-ec2:ec2SumTimeoutEnabled": true,
+    "@aws-cdk/aws-appsync:appSyncGraphQLAPIScopeLambdaPermission": true,
+    "@aws-cdk/aws-rds:setCorrectValueForDatabaseInstanceReadReplicaInstanceResourceId": true,
+    "@aws-cdk/core:cfnIncludeRejectComplexResourceUpdateCreatePolicyIntrinsics": true,
+    "@aws-cdk/aws-lambda-nodejs:sdkV3ExcludeSmithyPackages": true,
+    "@aws-cdk/aws-stepfunctions-tasks:fixRunEcsTaskPolicy": true
+  }
+}

java/http-proxy-apigateway/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+         xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.myorg</groupId>
+    <artifactId>http-proxy-apigateway</artifactId>
+    <version>0.1</version>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <cdk.version>2.171.1</cdk.version>
+        <constructs.version>[10.0.0,11.0.0)</constructs.version>
+        <junit.version>5.7.1</junit.version>
+        <maven.compiler.target>22</maven.compiler.target>
+        <maven.compiler.source>22</maven.compiler.source>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.11.0</version>
+                <configuration>
+                    <release>17</release>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <mainClass>com.myorg.HttpProxyApiGatewayApp</mainClass>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <!-- AWS Cloud Development Kit -->
+        <dependency>
+            <groupId>software.amazon.awscdk</groupId>
+            <artifactId>aws-cdk-lib</artifactId>
+            <version>${cdk.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>software.constructs</groupId>
+            <artifactId>constructs</artifactId>
+            <version>${constructs.version}</version>
+        </dependency>
+
+        <dependency>
+          <groupId>org.junit.jupiter</groupId>
+          <artifactId>junit-jupiter</artifactId>
+          <version>${junit.version}</version>
+          <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

java/http-proxy-apigateway/src/main/java/com/myorg/HttpProxyApiGatewayApp.java

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+package com.myorg;
+
+import software.amazon.awscdk.App;
+import software.amazon.awscdk.StackProps;
+
+public class HttpProxyApiGatewayApp {
+  public static void main(final String[] args) {
+    var app = new App();
+    var stackProps = StackProps.builder()
+      .stackName("HttpProxyApiGatewayStack")
+      .build();
+    new HttpProxyApiGatewayStack(app, "HttpProxyApiGatewayStack", stackProps);
+    app.synth();
+  }
+}

java/http-proxy-apigateway/src/main/java/com/myorg/HttpProxyApiGatewayStack.java

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+package com.myorg;
+
+import software.amazon.awscdk.CfnOutput;
+import software.amazon.awscdk.RemovalPolicy;
+import software.amazon.awscdk.Stack;
+import software.amazon.awscdk.StackProps;
+import software.amazon.awscdk.services.apigateway.*;
+import software.amazon.awscdk.services.lambda.*;
+import software.constructs.Construct;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import static software.amazon.awscdk.services.apigatewayv2.HttpMethod.ANY;
+import static software.amazon.awscdk.services.lambda.Runtime.PYTHON_3_12;
+
+public class HttpProxyApiGatewayStack extends Stack {
+
+  public record ProxyResourceParameters(String resourceId, String baseUrl, String httpMethod, String exampleRequest) {
+
+  }
+
+  private final RestApi restApi;
+
+  public HttpProxyApiGatewayStack(final Construct scope, final String id, final StackProps props) {
+    super(scope, id, props);
+    restApi = RestApi.Builder.create(this, "RestApi")
+      .restApiName("RestApi")
+      .cloudWatchRole(true)
+      .cloudWatchRoleRemovalPolicy(RemovalPolicy.DESTROY)
+      .endpointTypes(List.of(EndpointType.EDGE))
+      .build();
+    createHTTPTestAPIs().forEach(this::createProxyResource);
+  }
+
+  private List<ProxyResourceParameters> createHTTPTestAPIs() {
+    return Map.of(
+        "HelloFunction", "/hello?from=AWS",
+        "ByeFunction", "/bye?from=AWS"
+      ).entrySet().stream()
+      .map(functionEntry -> {
+        var functionName = functionEntry.getKey();
+        var parameters = functionEntry.getValue();
+        var function = Function.Builder.create(this, functionName)
+          .functionName(functionName)
+          .code(InlineCode.fromInline(getInlineCode("src/main/resources/lambdas/" + functionName + ".py")))
+          .handler("index.handler")
+          .runtime(PYTHON_3_12)
+          .build();
+        var lambdaFunctionAlias = Alias.Builder.create(this, functionName + "ProdAlias")
+          .aliasName("Prod")
+          .version(function.getCurrentVersion())
+          .build();
+        var functionURL = FunctionUrl.Builder.create(this, functionName + "Url")
+          .function(lambdaFunctionAlias)
+          .authType(FunctionUrlAuthType.NONE)
+          .invokeMode(InvokeMode.BUFFERED)
+          .cors(
+            FunctionUrlCorsOptions.builder()
+              .allowedOrigins(List.of("*"))
+              .allowedMethods(List.of(HttpMethod.GET))
+              .allowedHeaders(List.of("*"))
+              .build()
+          )
+          .build();
+        return new ProxyResourceParameters(functionName + "Resource", functionURL.getUrl(), ANY.name(), parameters);
+      }).collect(ArrayList::new, List::add, List::addAll);
+  }
+
+  private void createProxyResource(ProxyResourceParameters proxyResourceParameters) {
+    var parentProxyResource = restApi.getRoot().addResource(proxyResourceParameters.resourceId);
+    var proxyResource = ProxyResource.Builder.create(this, proxyResourceParameters.resourceId + "ProxyResource")
+      .parent(parentProxyResource)
+      .anyMethod(false)
+      .build();
+    var integrationOptions = IntegrationOptions.builder()
+      .requestParameters(
+        Map.of(
+          "integration.request.path.proxy", "method.request.path.proxy"
+        )
+      )
+      .build();
+    var httpIntegrationProps = HttpIntegrationProps.builder()
+      .proxy(true)
+      .httpMethod(proxyResourceParameters.httpMethod)
+      .options(integrationOptions)
+      .build();
+    var methodOptions = MethodOptions.builder()
+      .requestParameters(
+        Map.of(
+          "method.request.path.proxy", true
+        )
+      )
+      .build();
+    var httpIntegration = new HttpIntegration(proxyResourceParameters.baseUrl + "{proxy}", httpIntegrationProps);
+    proxyResource.addMethod(proxyResourceParameters.httpMethod, httpIntegration, methodOptions);
+    var proxyResourceUrl = restApi.urlForPath(proxyResource.getPath());
+    CfnOutput.Builder.create(this, proxyResourceParameters.resourceId + "ProxyUrl")
+      .value(proxyResourceUrl)
+      .build();
+    CfnOutput.Builder.create(this, proxyResourceParameters.resourceId + "Example")
+      .value(proxyResourceUrl.replace("/{proxy+}", proxyResourceParameters.exampleRequest))
+      .build();
+  }
+
+  private String getInlineCode(String path) {
+    try {
+      return new String(Files.readAllBytes(Path.of(path)));
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+}

java/http-proxy-apigateway/src/main/resources/lambdas/ByeFunction.py

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+import json
+def handler(event, context):
+    fromValue = event.get('queryStringParameters', {}).get('from', 'Lambda')
+    return {
+        'statusCode': 200,
+        'body': json.dumps('Bye from ' + fromValue + '!')
+    }

java/http-proxy-apigateway/src/main/resources/lambdas/HelloFunction.py

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+import json
+def handler(event, context):
+    fromValue = event.get('queryStringParameters', {}).get('from', 'Lambda')
+    return {
+        'statusCode': 200,
+        'body': json.dumps('Hello from ' + fromValue + '!')
+    }