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Allows Java applications written for a servlet container to run in AWS Lambda
/*
* Copyright 2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
* with the License. A copy of the License is located at
*
* http://aws.amazon.com/apache2.0/
*
* or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
* OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
*/
package com.amazonaws.serverless.proxy.internal;
import com.amazonaws.serverless.exceptions.ContainerInitializationException;
import com.amazonaws.serverless.proxy.LogFormatter;
import com.amazonaws.serverless.proxy.internal.servlet.ApacheCombinedServletLogFormatter;
import com.amazonaws.serverless.proxy.model.ContainerConfig;
import com.amazonaws.serverless.proxy.ExceptionHandler;
import com.amazonaws.serverless.proxy.RequestReader;
import com.amazonaws.serverless.proxy.ResponseWriter;
import com.amazonaws.serverless.proxy.SecurityContextWriter;
import com.amazonaws.services.lambda.runtime.Context;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.fasterxml.jackson.databind.ObjectWriter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.ws.rs.core.SecurityContext;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.concurrent.CountDownLatch;
/**
* Abstract class that declares the basic methods and objects for implementations of LambdaContainerHandler.
*
* @param The expected request object. This is the model class that the event JSON is de-serialized to
* @param The expected Lambda function response object. Responses from the container will be written to this model object
* @param The request type for the wrapped Java container
* @param The response or response writer type for the wrapped Java container
*/
public abstract class LambdaContainerHandler {
//-------------------------------------------------------------
// Constants
//-------------------------------------------------------------
public static final String SERVER_INFO = "aws-serverless-java-container";
//-------------------------------------------------------------
// Variables - Private
//-------------------------------------------------------------
private RequestReader requestReader;
private ResponseWriter responseWriter;
private SecurityContextWriter securityContextWriter;
private ExceptionHandler exceptionHandler;
private Class requestTypeClass;
private Class responseTypeClass;
protected Context lambdaContext;
private LogFormatter logFormatter;
private Logger log = LoggerFactory.getLogger(LambdaContainerHandler.class);
private ObjectReader objectReader;
private ObjectWriter objectWriter;
//-------------------------------------------------------------
// Variables - Private - Static
//-------------------------------------------------------------
private static ContainerConfig config = ContainerConfig.defaultConfig();
private static ObjectMapper objectMapper = new ObjectMapper();
//-------------------------------------------------------------
// Constructors
//-------------------------------------------------------------
protected LambdaContainerHandler(Class requestClass,
Class responseClass,
RequestReader requestReader,
ResponseWriter responseWriter,
SecurityContextWriter securityContextWriter,
ExceptionHandler exceptionHandler) {
log.info("Starting Lambda Container Handler");
requestTypeClass = requestClass;
responseTypeClass = responseClass;
this.requestReader = requestReader;
this.responseWriter = responseWriter;
this.securityContextWriter = securityContextWriter;
this.exceptionHandler = exceptionHandler;
objectReader = getObjectMapper().readerFor(requestTypeClass);
objectWriter = getObjectMapper().writerFor(responseTypeClass);
}
//-------------------------------------------------------------
// Methods - Abstract
//-------------------------------------------------------------
protected abstract ContainerResponseType getContainerResponse(ContainerRequestType request, CountDownLatch latch);
protected abstract void handleRequest(ContainerRequestType containerRequest, ContainerResponseType containerResponse, Context lambdaContext)
throws Exception;
public abstract void initialize()
throws ContainerInitializationException;
//-------------------------------------------------------------
// Methods - Public
//-------------------------------------------------------------
public static ObjectMapper getObjectMapper() {
return objectMapper;
}
/**
* Configures the library to strip a base path from incoming requests before passing them on to the wrapped
* framework. This was added in response to issue #34 (https://github.com/awslabs/aws-serverless-java-container/issues/34).
* When creating a base path mapping for custom domain names in API Gateway we want to be able to strip the base path
* from the request - the underlying service may not recognize this path.
* @param basePath The base path to be stripped from the request
*/
public void stripBasePath(String basePath) {
config.setStripBasePath(true);
config.setServiceBasePath(basePath);
}
/**
* Sets the formatter used to log request data in CloudWatch. By default this is set to use an Apache
* combined log format based on the servlet request and response object {@link ApacheCombinedServletLogFormatter}.
* @param formatter The log formatter object
*/
public void setLogFormatter(LogFormatter formatter) {
this.logFormatter = formatter;
}
/**
* Proxies requests to the underlying container given the incoming Lambda request. This method returns a populated
* return object for the Lambda function.
*
* @param request The incoming Lambda request
* @param context The execution context for the Lambda function
* @return A valid response type
*/
public ResponseType proxy(RequestType request, Context context) {
lambdaContext = context;
try {
SecurityContext securityContext = securityContextWriter.writeSecurityContext(request, context);
CountDownLatch latch = new CountDownLatch(1);
ContainerRequestType containerRequest = requestReader.readRequest(request, securityContext, context, config);
ContainerResponseType containerResponse = getContainerResponse(containerRequest, latch);
handleRequest(containerRequest, containerResponse, context);
latch.await();
if (logFormatter != null) {
log.info(SecurityUtils.crlf(logFormatter.format(containerRequest, containerResponse, securityContext)));
}
return responseWriter.writeResponse(containerResponse, context);
} catch (Exception e) {
log.error("Error while handling request", e);
return exceptionHandler.handle(e);
}
}
/**
* Handles Lambda RequestStreamHandler method. The method uses an ObjectMapper
* to transform the incoming input stream into the given {@link RequestType} and then calls the
* {@link #proxy(Object, Context)} method to handle the request. The output from the proxy method is
* written on the given output stream.
* @param input Lambda's incoming input stream
* @param output Lambda's response output stream
* @param context Lambda's context object
* @throws IOException If an error occurs during the stream processing
*/
public void proxyStream(InputStream input, OutputStream output, Context context)
throws IOException {
try {
RequestType request = objectReader.readValue(input);
ResponseType resp = proxy(request, context);
objectWriter.writeValue(output, resp);
} catch (JsonParseException e) {
log.error("Error while parsing request object stream", e);
getObjectMapper().writeValue(output, exceptionHandler.handle(e));
} catch (JsonMappingException e) {
log.error("Error while mapping object to RequestType class", e);
getObjectMapper().writeValue(output, exceptionHandler.handle(e));
}
}
//-------------------------------------------------------------
// Methods - Getter/Setter
//-------------------------------------------------------------
/**
* Returns the current container configuration object.
* @return The container configuration object
*/
public static ContainerConfig getContainerConfig() {
return config;
}
}