サーバーレスをJavaで組むためのSpring Cloud Function入門 / Introduction to Spring Cloud Function to build serverless in Java

by Y. Sakamoto

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「働きがいのある会社(GPTW)」ランキング(従業員25～99人部門) 1位を 3回受賞１位１位１位

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 19 AWS Lambdaの例 https://docs.aws.amazon.com/ja_jp/lambda/latest/dg/get-started-step4-optional.html より引用 public class Hello { public String myHandler(int myCount, Context context) { LambdaLogger logger = context.getLogger(); logger.log("received : " + myCount); return String.valueOf(myCount); } }

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 20 Azure Functionsの例 https://docs.microsoft.com/ja-jp/azure/azure-functions/functions-reference-java より引用 public class Function { public String echo(@HttpTrigger(name = "req", methods = {"post"}, authLevel = AuthorizationLevel.ANONYMOUS) String req, ExecutionContext context) { return String.format(req); } }

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public class Function { public String echo(@HttpTrigger(name = "req", methods = {"post"}, authLevel = AuthorizationLevel.ANONYMOUS) String req, ExecutionContext context) { return String.format(req); } } Copyright © Acroquest Technology Co., Ltd. All rights reserved. 21 Azure Functionsの例 https://docs.microsoft.com/ja-jp/azure/azure-functions/functions-reference-java より引用 java.util.Functionと同じ名前はやめようこれはいったい・・・型が合ってない

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 24 AWS Lambdaの例 public String myHandler(int myCount, Context context) { public String echo(@HttpTrigger(name = "req", methods = {"post"}, authLevel = AuthorizationLevel.ANONYMOUS) String req, ExecutionContext context) { Azure Functionsの例

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 32 Spring Cloud Function 業務ロジック (Function) AWS 基盤 Azure 基盤クラウドに依存しない関数定義 Open whisk 基盤 AWS Adapter Azure Adapter Openwhisk Adapter クラウド依存部分を吸収

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 48 @SpringBootApplication public class Application { public static void main(String... args) { SpringApplication.run(Application.class, args); } } メインクラス（ローカル起動用）普通のSpringBoot アプリと同じ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 49 @Component("echo") public class EchoFunction implements Function, Flux> { @Override public Flux apply(Flux requestParam) { return requestParam.map( param -> new EchoResponse(param.getMessage())); } } java.util.Functionを実装 Supplier/ConsumerもOK reactor.core.publisher.Flux 業務ロジック

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 51 AWS Lambda 基盤 SpringBootApiGateway RequestHandler EchoFunction API Gateway Lambda Spring Cloud Function SQSの場合は SpringBootRequestHandler 業務ロジック

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class EchoFunctionTest { @Test void echo() { EchoFunction echoFunction = new EchoFunction(); EchoRequest echoRequest = new EchoRequest(); echoRequest.setMessage("foo"); EchoResponse echoResponse = echoFunction.apply(echoRequest); assertThat(echoResponse.getMessage()).isEqualTo("foo"); } } Copyright © Acroquest Technology Co., Ltd. All rights reserved. 53 1. Springを使わない場合

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 54 class EchoFunctionTest { @Test void echoWithSpring() { System.setProperty("function.name", "echo"); try (SpringBootApiGatewayRequestHandler requestHandler = new SpringBootApiGatewayRequestHandler(Application.class)) { APIGatewayProxyRequestEvent requestEvent = new APIGatewayProxyRequestEvent().withBody("{¥"message¥":¥"foo¥"}"); APIGatewayProxyResponseEvent responseEvent = (APIGatewayProxyResponseEvent) requestHandler.handleRequest( requestEvent, null); assertThat(responseEvent.getBody()).isEqualTo("{¥"message¥":¥"foo¥"}"); } } } 呼び出す関数を指定 (デフォルトはfunction) 2. Springを使う場合 (API Gateway)

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 56 @SpringBootApplication public class Application { public static void main(String... args) { SpringApplication.run(Application.class); } @Bean WebClient webClient() { return WebClient.create(); } } SpringのWebClientを使ってみる SpringBootアプリと同じく Bean定義

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 57 SpringのWebClientを使ってみる @Component("dispatch") public class DispatchFunction implements Function, Flux> { private final WebClient webClient; private final Environment environment; public DispatchFunction(WebClient webClient, Environment environment) { this.webClient = webClient; this.environment = environment; } @Override public Flux apply(Flux requestParam) { String uri = environment.getProperty("app.echo.uri"); return requestParam.flatMap(param -> webClient .post().uri(uri).body(BodyInserters.fromObject(param)) .retrieve().bodyToMono(EchoResponse.class)); } } SpringBootアプリと同じく Autowired

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 59 Componentを自前で登録する @SpringBootApplication public class Application implements ApplicationContextInitializer { public static void main(String... args) { SpringApplication.run(Application.class, args); } Function echo() { return new EchoFunction(); } @Override public void initialize(GenericApplicationContext context) { context.registerBean("echo", FunctionRegistration.class, () -> new FunctionRegistration<>(echo()) .type(FunctionType.from(EchoRequest.class).to(EchoResponse.class))); } } class EchoFunctionからは @Componentを削除しておく Functionを1つずつ登録

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 61 spring.cloud.function: compile: upper: type: function inputType: dto.Message outputType: dto.Message lambda: message -> new dto.Message(message.getText().toUpperCase()) Bean名 supplier/function/consumer application.yml FunctionをLambda式で記述

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spring.cloud.function: compile: textGenerator: type: supplier outputType: Flux lambda: () -> Flux.fromIterable(List.of(new dto.Message("hoge"), new dto.Message("fuga"), new dto.Message("piyo"))) upper: type: function inputType: dto.Message outputType: dto.Message lambda: message -> new dto.Message(message.getText().toUpperCase()) decorator: type: function inputType: dto.Message outputType: dto.Message lambda: message -> new dto.Message("[" + message.getText() + "]") Copyright © Acroquest Technology Co., Ltd. All rights reserved. 63 application.yml printer: type: consumer inputType: dto.Message lambda: System.out::println task: supplier: textGenerator function: upper|decorator consumer: printer supplier/function/consumerと関連付ける「|」を使って複数のFunctionをつなげる

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 72 public Object handleRequest( E event, Context context) { initialize(); Object input = convertEvent(event); Publisher output = apply(extract(input)); return result(input, output); } SpringBootRequestHandler エントリーポイント初期化 →親クラスの SpringFunctionInitializerへ関数呼び出し

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 73 protected void initialize() { if (!this.initialized.compareAndSet( false, true)) { return; } logger.info("Initializing: " + this.configurationClass); SpringApplication builder = springApplication(); this.context = builder.run(); context.getAutowireCapableBeanFactory() .autowireBean(this); String name = context.getEnvironment() .getProperty("function.name"); if (name == null) { name = "function"; } if (this.catalog == null) { if (context.containsBean(name)) { this.function = getAndInstrumentFromContext(name); } } else { SpringFunctionInitializer SpringBoot 初期化呼び出すFunction名の取得

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 75 public Object handleRequest( E event, Context context) { initialize(); Object input = convertEvent(event); Publisher output = apply(extract(input)); return result(input, output); } protected Object convertEvent(E event) { return event; } private Flux extract(Object input) { if (input instanceof Collection) { return Flux.fromIterable((Iterable) input); } return Flux.just(input); } private Object result( Object input, Publisher output) { List result = new ArrayList<>(); for (Object value : Flux.from(output).toIterable()) { result.add(convertOutput(value)); } if (isSingleValue(input) && result.size() == 1) { return result.get(0); } return result; } SpringBootRequestHandler コレクションから Fluxに変換 Fluxからリストに変換

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@Override protected Object convertEvent(KinesisEvent event) { List payloads = deserializePayloads(event.getRecords()); if (functionAcceptsMessage()) { return wrapInMessages(payloads); } else { return payloads; } } Copyright © Acroquest Technology Co., Ltd. All rights reserved. 77 SpringBootKinesisEventHandler レコードのリストを取得 →Flux化 SpringBootRequestHandlerのサブクラス

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 79 SpringFunctionInitializer SpringBootRequestHandler SpringBootApiGateway RequestHandler SpringBootKinesisEventHandler SpringApplication FunctionalSpringApplication 継承依存手抜きクラス図

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. 81 1. Spring Cloud Functionで、ロジックを「Function」という形で抽象化して扱える 2. Reactorが使える、ただし効果の有無は注意 3. お宅訪問重要！ https://github.com/phonypianist/spring-cloud-function-example サンプルコードはここに置きました。

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