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Create Java cfn-response equivalent (aws-powertools#558)
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Introduces Java implementation of cfn-response module based on NodeJS design.
Put the sole class in a separate powertools-cloudformation Maven module.
100% code coverage

Addresses aws-powertools#558
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Joe Wolf committed Oct 22, 2021
1 parent 6d7a3a1 commit 2f1636a
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6 changes: 6 additions & 0 deletions pom.xml
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<module>powertools-parameters</module>
<module>powertools-validation</module>
<module>powertools-test-suite</module>
<module>powertools-cloudformation</module>
</modules>

<scm>
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<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>http-client-spi</artifactId>
<version>${aws.sdk.version}</version>
</dependency>
<dependency>
<groupId>io.burt</groupId>
<artifactId>jmespath-jackson</artifactId>
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89 changes: 89 additions & 0 deletions powertools-cloudformation/pom.xml
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<artifactId>powertools-cloudformation</artifactId>
<packaging>jar</packaging>

<parent>
<artifactId>powertools-parent</artifactId>
<groupId>software.amazon.lambda</groupId>
<version>1.7.3</version>
</parent>

<name>AWS Lambda Powertools Java library Cloudformation</name>
<description>
A suite of utilities for AWS Lambda Functions that makes tracing with AWS X-Ray, structured logging and creating
custom metrics asynchronously easier.
</description>
<url>https://aws.amazon.com/lambda/</url>
<issueManagement>
<system>GitHub Issues</system>
<url>https://github.com/awslabs/aws-lambda-powertools-java/issues</url>
</issueManagement>
<scm>
<url>https://github.com/awslabs/aws-lambda-powertools-java.git</url>
</scm>
<developers>
<developer>
<name>AWS Lambda Powertools team</name>
<organization>Amazon Web Services</organization>
<organizationUrl>https://aws.amazon.com/</organizationUrl>
</developer>
</developers>

<distributionManagement>
<snapshotRepository>
<id>ossrh</id>
<url>https://aws.oss.sonatype.org/content/repositories/snapshots</url>
</snapshotRepository>
</distributionManagement>

<dependencies>
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>http-client-spi</artifactId>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-core</artifactId>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-events</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
</dependency>

<!-- Test dependencies -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>

</project>
249 changes: 249 additions & 0 deletions ...rc/main/java/software/amazon/lambda/powertools/cloudformation/CloudFormationResponse.java
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package software.amazon.lambda.powertools.cloudformation;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.events.CloudFormationCustomResourceEvent;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategies;
import software.amazon.awssdk.http.Header;
import software.amazon.awssdk.http.HttpExecuteRequest;
import software.amazon.awssdk.http.HttpExecuteResponse;
import software.amazon.awssdk.http.SdkHttpClient;
import software.amazon.awssdk.http.SdkHttpMethod;
import software.amazon.awssdk.http.SdkHttpRequest;
import software.amazon.awssdk.utils.StringInputStream;

import java.io.IOException;
import java.net.URI;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
* Client for sending responses to AWS CloudFormation custom resources by way of a response URL, which is an Amazon S3
* pre-signed URL.
* <p>
* See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-lambda-function-code-cfnresponsemodule.html
*/
public class CloudFormationResponse {

/**
* Indicates if the function invoking send had successfully completed.
*/
public enum ResponseStatus {
SUCCESS, FAILED
}

/**
* Representation of the payload to be sent to the event target URL.
*/
@SuppressWarnings("unused")
static class ResponseBody {
private final String status;
private final String reason;
private final String physicalResourceId;
private final String stackId;
private final String requestId;
private final String logicalResourceId;
private final boolean noEcho;
private final Object data;

ResponseBody(CloudFormationCustomResourceEvent event,
Context context,
ResponseStatus responseStatus,
Object responseData,
String physicalResourceId,
boolean noEcho) {
requireNonNull(event, "CloudFormationCustomResourceEvent");
requireNonNull(context, "Context");
this.physicalResourceId = physicalResourceId != null ? physicalResourceId : context.getLogStreamName();
this.reason = "See the details in CloudWatch Log Stream: " + context.getLogStreamName();
this.status = responseStatus == null ? ResponseStatus.SUCCESS.name() : responseStatus.name();
this.stackId = event.getStackId();
this.requestId = event.getRequestId();
this.logicalResourceId = event.getLogicalResourceId();
this.noEcho = noEcho;
this.data = responseData;
}

public String getStatus() {
return status;
}

public String getReason() {
return reason;
}

public String getPhysicalResourceId() {
return physicalResourceId;
}

public String getStackId() {
return stackId;
}

public String getRequestId() {
return requestId;
}

public String getLogicalResourceId() {
return logicalResourceId;
}

public boolean isNoEcho() {
return noEcho;
}

public Object getData() {
return data;
}
}

/*
* Replace with java.util.Objects::requireNonNull when dropping JDK 8 support.
*/
private static <T> T requireNonNull(T arg, String argName) {
if (arg == null) {
throw new NullPointerException(argName + " cannot be null.");
}
return arg;
}

private final SdkHttpClient client;
private final ObjectMapper mapper;

/**
* Creates a new CloudFormationResponse that uses the provided HTTP client and default JSON serialization format.
*
* @param client HTTP client to use for sending requests; cannot be null
*/
public CloudFormationResponse(SdkHttpClient client) {
this(client, new ObjectMapper()
.setPropertyNamingStrategy(new PropertyNamingStrategies.UpperCamelCaseStrategy()));
}

/**
* Creates a new CloudFormationResponse that uses the provided HTTP client and the JSON serialization mapper object.
*
* @param client HTTP client to use for sending requests; cannot be null
* @param mapper for serializing response data; cannot be null
*/
protected CloudFormationResponse(SdkHttpClient client, ObjectMapper mapper) {
this.client = requireNonNull(client, "SdkHttpClient");
this.mapper = requireNonNull(mapper, "ObjectMapper");
}

/**
* Forwards a request containing a custom payload to the target resource specified by the event. The payload is
* formed from the event and context data.
*
* @param event custom CF resource event
* @param context used to specify when the function and any callbacks have completed execution, or to
* access information from within the Lambda execution environment.
* @param status whether the function successfully completed
* @return the response object
* @throws IOException when unable to generate or send the request
*/
public HttpExecuteResponse send(CloudFormationCustomResourceEvent event,
Context context,
ResponseStatus status) throws IOException {
return send(event, context, status, null);
}

/**
* Forwards a request containing a custom payload to the target resource specified by the event. The payload is
* formed from the event, status, and context data.
*
* @param event custom CF resource event
* @param context used to specify when the function and any callbacks have completed execution, or to
* access information from within the Lambda execution environment.
* @param status whether the function successfully completed
* @param responseData response data, e.g. a list of name-value pairs. May be null.
* @return the response object
* @throws IOException when unable to generate or send the request
*/
public HttpExecuteResponse send(CloudFormationCustomResourceEvent event,
Context context,
ResponseStatus status,
Object responseData) throws IOException {
return send(event, context, status, responseData, null);
}

/**
* Forwards a request containing a custom payload to the target resource specified by the event. The payload is
* formed from the event, status, response, and context data.
*
* @param event custom CF resource event
* @param context used to specify when the function and any callbacks have completed execution, or to
* access information from within the Lambda execution environment.
* @param status whether the function successfully completed
* @param responseData response data, e.g. a list of name-value pairs. May be null.
* @param physicalResourceId Optional. The unique identifier of the custom resource that invoked the function. By
* default, the module uses the name of the Amazon CloudWatch Logs log stream that's
* associated with the Lambda function.
* @return the response object
* @throws IOException when unable to generate or send the request
*/
public HttpExecuteResponse send(CloudFormationCustomResourceEvent event,
Context context,
ResponseStatus status,
Object responseData,
String physicalResourceId) throws IOException {
return send(event, context, status, responseData, physicalResourceId, false);
}

/**
* Forwards a request containing a custom payload to the target resource specified by the event. The payload is
* formed from the event, status, response, and context data.
*
* @param event custom CF resource event
* @param context used to specify when the function and any callbacks have completed execution, or to
* access information from within the Lambda execution environment.
* @param status whether the function successfully completed
* @param responseData response data, e.g. a list of name-value pairs. May be null.
* @param physicalResourceId Optional. The unique identifier of the custom resource that invoked the function. By
* default, the module uses the name of the Amazon CloudWatch Logs log stream that's
* associated with the Lambda function.
* @param noEcho Optional. Indicates whether to mask the output of the custom resource when it's
* retrieved by using the Fn::GetAtt function. If set to true, all returned values are
* masked with asterisks (*****), except for information stored in the locations specified
* below. By default, this value is false.
* @return the response object
* @throws IOException when unable to generate or send the request
*/
public HttpExecuteResponse send(CloudFormationCustomResourceEvent event,
Context context,
ResponseStatus status,
Object responseData,
String physicalResourceId,
boolean noEcho) throws IOException {
ResponseBody body = new ResponseBody(event, context, status, responseData, physicalResourceId, noEcho);
URI uri = URI.create(event.getResponseUrl());

// no need to explicitly close in-memory stream
StringInputStream stream = new StringInputStream(mapper.writeValueAsString(body));
SdkHttpRequest request = SdkHttpRequest.builder()
.uri(uri)
.method(SdkHttpMethod.PUT)
.headers(headers(stream.available()))
.build();
HttpExecuteRequest httpExecuteRequest = HttpExecuteRequest.builder()
.request(request)
.contentStreamProvider(() -> stream)
.build();
return client.prepareRequest(httpExecuteRequest).call();
}

/**
* Generates HTTP headers to be supplied in the CloudFormation request.
*
* @param contentLength the length of the payload
* @return HTTP headers
*/
protected Map<String, List<String>> headers(int contentLength) {
Map<String, List<String>> headers = new HashMap<>();
headers.put(Header.CONTENT_TYPE, Collections.emptyList()); // intentionally empty
headers.put(Header.CONTENT_LENGTH, Collections.singletonList(Integer.toString(contentLength)));
return headers;
}
}
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