feat:add a multi rule ALB sample with host and path based routing (#257)

* add a multi rule ALB sample with a combination of host and path based routing
* Update java/alb-multi-rule-response/README.md

java/alb-multi-rule-response/.gitignore

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

java/alb-multi-rule-response/README.md

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+<!--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 examples does is built on Construct Libraries marked "Stable" and does not have any infrastructure prerequisites to build.
+
+---
+<!--END STABILITY BANNER-->
+
+# ALB using a combination of host and path based routing with Java AWS-CDK 
+The ALB is backed by an EC2 instance acting as frontend client and built-in ALB response rules that simulates mobile and application api
+
+## Testing the responses
+### testing mobile produciton api
+``` bash 
+curl -H "Host: mobile.mydomain.com" [ALB-DNS-FQDN]/production
+```
+Resonse received
+```json
+{"status":"succes","apiversion":"prod_mobile_v1"}
+```
+
+### Testing frontend production api
+``` bash 
+curl -H "Host: api.mydomain.com" [ALB-DNS-FQDN]/production
+```
+
+```json
+{"status":"succes","apiversion":"prod_api_v1"}
+```
+
+## List of ALB rules
+![alt text](imgs/screenshot.png "screenshot of resulting rule")
+
+
+It is a Maven-based project, so you can open this directory with any Maven-compatible Java IDE, and you should be able to build and run tests from your IDE.
+
+You should explore the contents of this template. It demonstrates a CDK app to create a multi-rule ALB, based on path and host headers.  
+More information on ALB and Path routing is available here https://docs.aws.amazon.com/elasticloadbalancing/latest/application/tutorial-load-balancer-routing.html
+
+The cdk.json file tells the CDK Toolkit how to execute your app. This example relies on maven to do that.
+
+## 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
+
+Enjoy!

java/alb-multi-rule-response/cdk.json

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+{
+  "app": "mvn -e -q exec:java"
+}

java/alb-multi-rule-response/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>albcdkproject</artifactId>
+    <version>0.1</version>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>1.6.0</version>
+                <configuration>
+                    <mainClass>com.myorg.ALBProjectApp</mainClass>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <!-- AWS Cloud Development Kit -->
+        <dependency>
+            <groupId>software.amazon.awscdk</groupId>
+            <artifactId>core</artifactId>
+            <version>[1.26.0, 2)</version>
+        </dependency>
+
+        <dependency>
+            <groupId>software.amazon.awscdk</groupId>
+            <artifactId>elasticloadbalancingv2</artifactId>
+            <version>[1.26.0, 2)</version>
+        </dependency>
+        <dependency>
+            <groupId>software.amazon.awscdk</groupId>
+            <artifactId>ec2</artifactId>
+            <version>[1.26.0, 2)</version>
+        </dependency>
+        <dependency>
+            <groupId>software.amazon.awscdk</groupId>
+            <artifactId>autoscaling</artifactId>
+            <version>[1.26.0,2)</version>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/junit/junit -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

java/alb-multi-rule-response/src/main/java/com/myorg/ALBProjectApp.java

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+package com.myorg;
+
+import software.amazon.awscdk.core.App;
+import software.amazon.awscdk.core.Environment;
+import software.amazon.awscdk.core.StackProps;
+
+public class ALBProjectApp {
+  public static void main(final String[] args) {
+    App app = new App();
+
+    new ALBProjectStack(
+        app, "ALBProjectStack", StackProps.builder().env(Environment.builder().build()).build());
+    app.synth();
+  }
+}

java/alb-multi-rule-response/src/main/java/com/myorg/ALBProjectStack.java

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+package com.myorg;
+
+import com.myorg.utils.PropertyLoader;
+import java.util.ArrayList;
+import java.util.List;
+import software.amazon.awscdk.core.Construct;
+import software.amazon.awscdk.core.Stack;
+import software.amazon.awscdk.core.StackProps;
+import software.amazon.awscdk.services.autoscaling.AutoScalingGroup;
+import software.amazon.awscdk.services.ec2.AmazonLinuxImage;
+import software.amazon.awscdk.services.ec2.InstanceClass;
+import software.amazon.awscdk.services.ec2.InstanceSize;
+import software.amazon.awscdk.services.ec2.InstanceType;
+import software.amazon.awscdk.services.ec2.Vpc;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ApplicationListener;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ApplicationListenerRule;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ApplicationLoadBalancer;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ApplicationProtocol;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ApplicationTargetGroup;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ApplicationTargetGroupProps;
+import software.amazon.awscdk.services.elasticloadbalancingv2.ContentType;
+import software.amazon.awscdk.services.elasticloadbalancingv2.FixedResponse;
+import software.amazon.awscdk.services.elasticloadbalancingv2.IApplicationLoadBalancerTarget;
+import software.amazon.awscdk.services.elasticloadbalancingv2.IApplicationTargetGroup;
+import software.amazon.awscdk.services.elasticloadbalancingv2.TargetType;
+
+public class ALBProjectStack extends Stack {
+
+  public ALBProjectStack(final Construct scope, final String id) {
+    this(scope, id, null);
+  }
+
+  public ALBProjectStack(final Construct scope, final String id, final StackProps props) {
+    super(scope, id, props);
+
+    // property loader
+    PropertyLoader propertyLoad = new PropertyLoader();
+
+    // create ALB and all anciliarry services
+    Vpc vpc = Vpc.Builder.create(this, "VPC").build();
+    AutoScalingGroup asg =
+        AutoScalingGroup.Builder.create(this, "ASG")
+            .vpc(vpc)
+            .instanceType(InstanceType.of(InstanceClass.BURSTABLE2, InstanceSize.MICRO))
+            .userData(propertyLoad.getUserData())
+            .machineImage(new AmazonLinuxImage())
+            .build();
+
+    ApplicationLoadBalancer lb =
+        ApplicationLoadBalancer.Builder.create(this, "LB")
+            .vpc(vpc)
+            .internetFacing(Boolean.TRUE)
+            .loadBalancerName("myalb")
+            .build();
+
+    List<IApplicationLoadBalancerTarget> targets = new ArrayList<IApplicationLoadBalancerTarget>();
+    targets.add(asg);
+
+    ApplicationTargetGroup webTargetGroup =
+        new ApplicationTargetGroup(
+            this,
+            "MyTargetGroup",
+            ApplicationTargetGroupProps.builder()
+                .vpc(vpc)
+                .targetType(TargetType.INSTANCE)
+                .targets(targets)
+                .port(80)
+                .protocol(ApplicationProtocol.HTTP)
+                .build());
+
+    List<IApplicationTargetGroup> targetGroups = new ArrayList<IApplicationTargetGroup>();
+    targetGroups.add(webTargetGroup);
+
+    // default listener
+    ApplicationListener http =
+        ApplicationListener.Builder.create(this, "HTTP")
+            .port(80)
+            .protocol(ApplicationProtocol.HTTP)
+            .open(true)
+            .loadBalancer(lb)
+            .defaultTargetGroups(targetGroups)
+            .build();
+
+    // adding application listern rules
+    ApplicationListenerRule alrProdApi =
+        ApplicationListenerRule.Builder.create(this, "prodApi")
+            .pathPattern("/production")
+            .priority(1)
+            .listener(http)
+            .hostHeader(propertyLoad.getRestAPIHostHeader())
+            .build();
+
+    ApplicationListenerRule alrProdM =
+        ApplicationListenerRule.Builder.create(this, "prodMobile")
+            .pathPattern("/production")
+            .priority(2)
+            .listener(http)
+            .hostHeader(propertyLoad.getRestMobileHostHeader())
+            .build();
+
+    ApplicationListenerRule alrSandboxApi =
+        ApplicationListenerRule.Builder.create(this, "sandboxApi")
+            .pathPattern("/sandbox")
+            .priority(3)
+            .listener(http)
+            .hostHeader(propertyLoad.getRestAPIHostHeader())
+            .build();
+
+    ApplicationListenerRule alrSandboxM =
+        ApplicationListenerRule.Builder.create(this, "sandboxMobile")
+            .pathPattern("/sandbox")
+            .priority(4)
+            .listener(http)
+            .hostHeader(propertyLoad.getRestMobileHostHeader())
+            .build();
+
+    // adding fixed responses
+    alrProdApi.addFixedResponse(
+        FixedResponse.builder()
+            .statusCode("200")
+            .contentType(ContentType.APPLICATION_JSON)
+            .messageBody(propertyLoad.getProdApiMessageBody())
+            .build());
+
+    alrProdM.addFixedResponse(
+        FixedResponse.builder()
+            .statusCode("200")
+            .contentType(ContentType.APPLICATION_JSON)
+            .messageBody(propertyLoad.getProdMobileMessageBody())
+            .build());
+
+    alrSandboxApi.addFixedResponse(
+        FixedResponse.builder()
+            .statusCode("200")
+            .contentType(ContentType.APPLICATION_JSON)
+            .messageBody(propertyLoad.getSandboxApiMessageBody())
+            .build());
+
+    alrSandboxM.addFixedResponse(
+        FixedResponse.builder()
+            .statusCode("200")
+            .contentType(ContentType.APPLICATION_JSON)
+            .messageBody(propertyLoad.getSandboxMobileMessageBody())
+            .build());
+  }
+}

java/alb-multi-rule-response/src/main/java/com/myorg/utils/PropertyLoader.java

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+package com.myorg.utils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Properties;
+import software.amazon.awscdk.services.ec2.UserData;
+
+public class PropertyLoader {
+
+  private final UserData userData;
+  private String prodMobileMessageBody;
+  private String prodApiMessageBody;
+  private String sandboxApiMessageBody;
+  private String sandboxMobileMessageBody;
+  private String restAPIHostHeader;
+  private String restMobileHostHeader;
+
+  public PropertyLoader() {
+    userData = UserData.forLinux();
+    load();
+  }
+
+  public UserData getUserData() {
+    return userData;
+  }
+
+  public String getProdMobileMessageBody() {
+    return prodMobileMessageBody;
+  }
+
+  public String getProdApiMessageBody() {
+    return prodApiMessageBody;
+  }
+
+  public String getSandboxApiMessageBody() {
+    return sandboxApiMessageBody;
+  }
+
+  public String getSandboxMobileMessageBody() {
+    return sandboxMobileMessageBody;
+  }
+
+  public String getRestAPIHostHeader() {
+    return restAPIHostHeader;
+  }
+
+  public String getRestMobileHostHeader() {
+    return restMobileHostHeader;
+  }
+
+  private void load() {
+    // start loading data from the properties files
+    try (InputStream input =
+        PropertyLoader.class.getClassLoader().getResourceAsStream("mydata.properties")) {
+
+      Properties prop = new Properties();
+      if (input == null) {
+        System.out.println("unable to find mydata.properties");
+        return;
+      }
+
+      // get the values from the properties file
+      prop.load(input);
+
+      // start populating values
+      prodMobileMessageBody = prop.getProperty("response.prodMobileV1");
+      prodApiMessageBody = prop.getProperty("response.prodApiV1");
+      sandboxApiMessageBody = prop.getProperty("response.sandboxApiV1");
+      sandboxMobileMessageBody = prop.getProperty("response.sandboxMobileV1");
+      restAPIHostHeader = prop.getProperty("rest.api");
+      restMobileHostHeader = prop.getProperty("rest.mobile");
+
+      String[] cmds = prop.getProperty("userData.commands").split("\n");
+      if (cmds.length > 0) {
+        for (String cmd : cmds) {
+          userData.addCommands(cmd);
+        }
+      }
+    } catch (IOException ex) {
+      ex.printStackTrace();
+    }
+  }
+}