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The AWS Java SDK for AWS Lambda module holds the client classes that are used for communicating with AWS Lambda Service
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/*
* Copyright 2015-2024 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.services.lambda.invoke;
import com.amazonaws.services.lambda.AWSLambda;
import com.amazonaws.services.lambda.AWSLambdaAsyncClientBuilder;
import com.amazonaws.services.lambda.model.InvocationType;
import com.amazonaws.services.lambda.model.InvokeRequest;
import com.amazonaws.services.lambda.model.InvokeResult;
import com.amazonaws.services.lambda.model.LogType;
import com.amazonaws.util.Base64;
import com.amazonaws.util.BinaryUtils;
import com.amazonaws.util.StringUtils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.nio.ByteBuffer;
/**
* A factory for objects that implement a user-supplied interface by invoking a remote Lambda
* function.
*
*
* public class Request {
* // Standard POJO stuff here modeling the input your Lambda function
* // expects.
* }
*
* public class Result {
* // More standard POJO stuff here modeling the output your Lambda
* // function produces.
* }
*
* public interface LambdaFunctions {
*
* @LambdaFunction
* Result doSomeStuff(Request request);
* }
* LambdaFunctions functions = LambdaInvokerFactory.builder()
* .lambdaClient(AWSLambdaSyncClientBuilder.standard()
* .withCredentials(new ProfileCredentialsProvider("myprofile"))
* .build())
* .build(LambdaFunctions.class);
* Request request = new Request(...);
* Result result = functions.doSomeStuff(request);
*
*/
public final class LambdaInvokerFactory {
static final ObjectMapper DEFAULT_MAPPER = new ObjectMapper()
.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
/**
* Creates a new Lambda invoker implementing the given interface and wrapping the given {@code AWSLambda} client.
*
* @param interfaceClass the interface to implement
* @param awsLambda the lambda client to use for making remote calls
* @deprecated Use {@link LambdaInvokerFactory#builder()} to configure invoker factory.
*/
@Deprecated
public static T build(Class interfaceClass, AWSLambda awsLambda) {
return build(interfaceClass, awsLambda, new LambdaInvokerFactoryConfig());
}
/**
* Creates a new Lambda invoker implementing the given interface and wrapping the given {@code AWSLambda} client.
*
* @param interfaceClass the interface to implement
* @param awsLambda the lambda client to use for making remote calls
* @param config configuration for the LambdaInvokerFactory
* @deprecated Use {@link LambdaInvokerFactory#builder()} to configure invoker factory.
*/
@Deprecated
public static T build(Class interfaceClass, AWSLambda awsLambda, LambdaInvokerFactoryConfig config) {
final Object proxy = Proxy.newProxyInstance(interfaceClass.getClassLoader(),
new Class[]{interfaceClass},
new LambdaInvocationHandler(interfaceClass, awsLambda, config));
return interfaceClass.cast(proxy);
}
/**
* @return An instance of {@link Builder} to configure an invoker factory and build proxies for
* invoking remote lambda functions.
*/
public static Builder builder() {
return new Builder();
}
public static class Builder {
private LambdaFunctionNameResolver functionNameResolver;
private String functionAlias;
private String functionVersion;
private AWSLambda lambda;
private ObjectMapper objectMapper;
/**
* Sets a new Function name resolver to override the default behavior.
*
* @param functionNameResolver Implementation of {@link LambdaFunctionNameResolver}
* @return The current object for method chaining.
*/
public Builder lambdaFunctionNameResolver(
LambdaFunctionNameResolver functionNameResolver) {
this.functionNameResolver = functionNameResolver;
return this;
}
private LambdaFunctionNameResolver resolveFunctionNameResolver() {
return functionNameResolver == null ? new DefaultLambdaFunctionNameResolver() :
functionNameResolver;
}
/**
* Sets the ObjectMapper used to (de-)serialize payload if you do not wish to use the default mapper.
* (see {@link ObjectMapper} for configuration options)
*
* The FAIL_ON_UNKNOWN_PROPERTIES property MUST be disabled for any custom object mapper so that
* the response unmarshalling is forward compatible with any new fields your Lambda function may return but might
* not be modeled.
*
* @return This current object for method chaining.
*/
public Builder objectMapper(ObjectMapper objectMapper) {
if (objectMapper.isEnabled(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)) {
throw new IllegalArgumentException("FAIL_ON_UNKNOWN_PROPERTIES must be disabled on any custom ObjectMapper used");
}
this.objectMapper = objectMapper;
return this;
}
private ObjectMapper resolveObjectMapper() {
return null != this.objectMapper ? this.objectMapper : DEFAULT_MAPPER;
}
/**
* Sets the function alias to invoke. See Versioning
* & Aliases for more information on aliases.
*
* @return This current object for method chaining.
*/
public Builder functionAlias(String functionAlias) {
this.functionAlias = functionAlias;
return this;
}
/**
* Sets the function version to invoke. See Versioning
* & Aliases for more information on function versions.
*
* @return This current object for method chaining.
*/
public Builder functionVersion(String functionVersion) {
this.functionVersion = functionVersion;
return this;
}
/**
* Sets the client to use to call AWS Lambda. If not set a default client is used (see {@link
* AWSLambdaAsyncClientBuilder#defaultClient()}).
*
* @param lambda Client instance to use.
* @return This current object for method chaining.
*/
public Builder lambdaClient(AWSLambda lambda) {
this.lambda = lambda;
return this;
}
private AWSLambda resolveLambdaClient() {
return lambda == null ? AWSLambdaAsyncClientBuilder.defaultClient() : lambda;
}
/**
* Build a remote proxy of the given interface to make calls to AWS Lambda.
*
* @param interfaceClass Interface class to proxy.
* @param Interface type.
* @return This current object for method chaining.
*/
public T build(Class interfaceClass) {
return LambdaInvokerFactory.build(interfaceClass, resolveLambdaClient(), getConfiguration());
}
private LambdaInvokerFactoryConfig getConfiguration() {
return new LambdaInvokerFactoryConfig(resolveFunctionNameResolver(), resolveObjectMapper(),
functionAlias, functionVersion);
}
}
private LambdaInvokerFactory() {
}
private static class LambdaInvocationHandler implements InvocationHandler {
private final AWSLambda awsLambda;
private final Log log;
private final LambdaInvokerFactoryConfig config;
private final ObjectMapper mapper;
public LambdaInvocationHandler(Class interfaceClass, AWSLambda awsLambda, LambdaInvokerFactoryConfig config) {
this.awsLambda = awsLambda;
this.log = LogFactory.getLog(interfaceClass);
this.config = config;
this.mapper = config.getObjectMapper();
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (method.getName().equals("toString")) {
return this.toString();
} else if (method.getName().equals("hashCode")) {
return this.hashCode();
}
LambdaFunction annotation = validateInterfaceMethod(method, args);
InvokeRequest invokeRequest = buildInvokeRequest(method, annotation, args == null ? null : args[0]);
InvokeResult invokeResult = awsLambda.invoke(invokeRequest);
return processInvokeResult(method, invokeResult);
}
/**
* Verifies that the given method is annotated appropriately.
*/
private LambdaFunction validateInterfaceMethod(Method method, Object[] args) {
LambdaFunction annotation = method.getAnnotation(LambdaFunction.class);
if (annotation == null) {
throw new LambdaSerializationException("No LambdaFunction annotation for method " + method.getName());
}
if (annotation.invocationType() != InvocationType.RequestResponse && annotation.logType() != LogType.None) {
throw new LambdaSerializationException("InvocationType must be RequestResponse if LogType " + "is set");
}
if (args != null && args.length > 1) {
throw new LambdaSerializationException("LambdaFunctions take either 0 or 1 arguments");
}
return annotation;
}
/**
* Builds an InvokeRequest from the given method, its {@code LambdaFunction} annotation, and
* the input parameter (if any).
*/
private InvokeRequest buildInvokeRequest(Method method, LambdaFunction annotation, Object input) {
InvokeRequest invokeRequest = new InvokeRequest();
String functionName = config.getLambdaFunctionNameResolver().getFunctionName(method, annotation, config);
invokeRequest.setFunctionName(functionName);
if (hasQualifier()) {
invokeRequest.setQualifier(getQualifier());
}
invokeRequest.setInvocationType(annotation.invocationType());
invokeRequest.setLogType(annotation.logType());
if (input != null) {
try {
String payload = mapper.writer().writeValueAsString(input);
if (log.isDebugEnabled()) {
log.debug("Serialized request object to '" + payload + "'");
}
invokeRequest.setPayload(payload);
} catch (JsonProcessingException ex) {
throw new LambdaSerializationException("Failed to serialize request object to JSON", ex);
}
}
return invokeRequest;
}
private boolean hasQualifier() {
return getQualifier() != null;
}
private String getQualifier() {
return config.getFunctionAlias() == null ? config.getFunctionVersion() :
config.getFunctionAlias();
}
/**
* Process the result of invoking a remote function. If the response includes server-side
* logs, dump them into our logs; if it includes a server-side error indication, parse it
* into a corresponding {@code Exception} type, otherwise parse the result payload into a
* Java object suitable for returning from this method.
*/
private Object processInvokeResult(Method method, InvokeResult invokeResult) throws Throwable {
if (invokeResult.getLogResult() != null && log.isInfoEnabled()) {
try {
String decoded = new String(Base64.decode(invokeResult.getLogResult()), StringUtils.UTF8);
log.info(method.getName() + " log:\n\t" + decoded.replaceAll("\n", "\n\t"));
} catch (Exception ex) {
log.warn("Error decoding log result '" + invokeResult.getLogResult() + "'", ex);
}
}
String functionError = invokeResult.getFunctionError();
if (functionError == null) {
// Success.
return getObjectFromPayload(method, invokeResult);
} else {
throw getExceptionFromPayload(method, invokeResult);
}
}
/**
* Reads a Java object suitable for returning from the given method from the payload of the
* given {@code InvokeResult} (or returns {@code null} if the method has no return value or
* the response contains no payload).
*
* @throws LambdaSerializationException
* on error deserializing
*/
private Object getObjectFromPayload(Method method, InvokeResult invokeResult) {
try {
return getObjectFromPayload(method.getGenericReturnType(), invokeResult.getPayload());
} catch (IOException ex) {
throw new LambdaSerializationException("Failed to parse Lambda function result", ex);
}
}
/**
* Unmarshall the exception from the response payload. The invoker factory supports unmarshalling into custom exceptions
* that are declared on the method signature (in the interface the invoker factory proxies).
*
* @param method Method being proxied
* @param invokeResult Result from AWS Lambda.
* @return Exception to throw back to the caller. May either be a custom exception declared in the interface, a generic
* exception unmarshalled from the payload, or a very generic exception if we can't unmarshall the payload.
*/
private Throwable getExceptionFromPayload(Method method, InvokeResult invokeResult) {
try {
LambdaFunctionException error = getObjectFromPayload(LambdaFunctionException.class, invokeResult.getPayload());
error.setFunctionError(invokeResult.getFunctionError());
error.fillInStackTrace(method.getDeclaringClass());
return getExceptionToThrow(method, error);
} catch (Exception ex) {
log.warn("Error parsing exception information from response payload", ex);
return new LambdaFunctionException("Unexpected error executing Lambda function",
invokeResult.getFunctionError());
}
}
/**
* Get the correct exception to throw back to the caller.
*
* @param method Interface method we are proxying
* @param error Unmarshalled error payload
* @return A custom exception if the error matches any thrown by the interface method or the original {@link
* LambdaFunctionException} if none matches.
*/
private Throwable getExceptionToThrow(Method method, LambdaFunctionException error) {
final String type = error.getType();
final Constructor constructor = findConstructor(findCustomExceptionClass(method, type));
if (constructor != null) {
try {
final Throwable toReturn = (Throwable) constructor.newInstance(error.getMessage());
toReturn.setStackTrace(error.getStackTrace());
return toReturn;
} catch (Exception ex) {
log.warn("Error constructing custom exception", ex);
}
}
return error;
}
/**
* Search the method throws clause to find an exception that matches the error type.
*
* @param method We only consider exception types that are explicitly declared in the interface for the proxied method.
* @param type Error type returned by AWS Lambda.
* @return Custom exception class to create or null to use default exception.
*/
private Class findCustomExceptionClass(Method method, String type) {
if (type != null) {
for (Class exceptionType : method.getExceptionTypes()) {
if (exceptionType.getName().equals(type) || exceptionType.getSimpleName().equals(type)) {
return exceptionType;
}
}
}
return null;
}
/**
* For custom exceptions we expect to find a accessible constructor that takes a String parameter (for the error message)
*
* @param type Exception class
* @return Applicable constructor or null if not found.
*/
private Constructor findConstructor(Class type) {
if (type == null) {
return null;
}
for (Constructor constructor : type.getConstructors()) {
Class[] params = constructor.getParameterTypes();
if (params != null && params.length == 1 && String.class.equals(params[0])) {
return constructor;
}
}
return null;
}
private T getObjectFromPayload(Class type, ByteBuffer payload) throws IOException {
return type.cast(getObjectFromPayload((Type) type, payload));
}
private Object getObjectFromPayload(Type type, ByteBuffer payload) throws IOException {
if (type == void.class || payload.remaining() == 0) {
return null;
}
JavaType javaType = mapper.getTypeFactory().constructType(type);
return mapper.reader(javaType).readValue(BinaryUtils.copyAllBytesFrom(payload));
}
}
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