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<title>9. Serverless Platform Adapters</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="multi_spring-cloud-function.html" title="Spring Cloud Function"><link rel="up" href="multi_spring-cloud-function.html" title="Spring Cloud Function"><link rel="prev" href="multi__dynamic_compilation.html" title="8. Dynamic Compilation"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">9. Serverless Platform Adapters</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__dynamic_compilation.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> </td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="_serverless_platform_adapters" href="#_serverless_platform_adapters"></a>9. Serverless Platform Adapters</h1></div></div></div><p>As well as being able to run as a standalone process, a Spring Cloud
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Function application can be adapted to run one of the existing
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serverless platforms. In the project there are adapters for
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<a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-aws" target="_top">AWS
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Lambda</a>,
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<a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-azure" target="_top">Azure</a>,
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and
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<a class="link" href="https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk" target="_top">Apache
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OpenWhisk</a>. The <a class="link" href="https://github.com/fnproject/fn" target="_top">Oracle Fn platform</a>
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has its own Spring Cloud Function adapter. And
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<a class="link" href="https://projectriff.io" target="_top">Riff</a> supports Java functions and its
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<a class="link" href="https://github.com/projectriff/java-function-invoker" target="_top">Java Function
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Invoker</a> acts natively is an adapter for Spring Cloud Function jars.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_aws_lambda" href="#_aws_lambda"></a>9.1 AWS Lambda</h2></div></div></div><p>The <a class="link" href="https://aws.amazon.com/" target="_top">AWS</a> adapter takes a Spring Cloud Function app and converts it to a form that can run in AWS Lambda.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_introduction_2" href="#_introduction_2"></a>9.1.1 Introduction</h3></div></div></div><p>The adapter has a couple of generic request handlers that you can use. The most generic is <code class="literal">SpringBootStreamHandler</code>, which uses a Jackson <code class="literal">ObjectMapper</code> provided by Spring Boot to serialize and deserialize the objects in the function. There is also a <code class="literal">SpringBootRequestHandler</code> which you can extend, and provide the input and output types as type parameters (enabling AWS to inspect the class and do the JSON conversions itself).</p><p>If your app has more than one <code class="literal">@Bean</code> of type <code class="literal">Function</code> etc. then you can choose the one to use by configuring <code class="literal">function.name</code> (e.g. as <code class="literal">FUNCTION_NAME</code> environment variable in AWS). The functions are extracted from the Spring Cloud <code class="literal">FunctionCatalog</code> (searching first for <code class="literal">Function</code> then <code class="literal">Consumer</code> and finally <code class="literal">Supplier</code>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_notes_on_jar_layout" href="#_notes_on_jar_layout"></a>9.1.2 Notes on JAR Layout</h3></div></div></div><p>You don’t need the Spring Cloud Function Web or Stream adapter at runtime in Lambda, so you might need to exclude those before you create the JAR you send to AWS. A Lambda application has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample). The sample app creates 2 jar files, one with an <code class="literal">aws</code> classifier for deploying in Lambda, and one executable (thin) jar that includes <code class="literal">spring-cloud-function-web</code> at runtime. Spring Cloud Function will try and locate a "main class" for you from the JAR file manifest, using the <code class="literal">Start-Class</code> attribute (which will be added for you by the Spring Boot tooling if you use the starter parent). If there is no <code class="literal">Start-Class</code> in your manifest you can use an environment variable <code class="literal">MAIN_CLASS</code> when you deploy the function to AWS.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_upload" href="#_upload"></a>9.1.3 Upload</h3></div></div></div><p>Build the sample under <code class="literal">spring-cloud-function-samples/function-sample-aws</code> and upload the <code class="literal">-aws</code> jar file to Lambda. The handler can be <code class="literal">example.Handler</code> or <code class="literal">org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler</code> (FQN of the class, <span class="emphasis"><em>not</em></span> a method reference, although Lambda does accept method references).</p><pre class="screen">./mvnw -U clean package</pre><p>Using the AWS command line tools it looks like this:</p><pre class="screen">aws lambda create-function --function-name Uppercase --role arn:aws:iam::[USERID]:role/service-role/[ROLE] --zip-file fileb://function-sample-aws/target/function-sample-aws-1.0.0.RELEASE-aws.jar --handler org.springframework.cloud.function.adapter.aws.SpringBootStreamHandler --description "Spring Cloud Function Adapter Example" --runtime java8 --region us-east-1 --timeout 30 --memory-size 1024 --publish</pre><p>The input type for the function in the AWS sample is a Foo with a single property called "value". So you would need this to test it:</p><pre class="screen">{
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"value": "test"
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}</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_platfom_specific_features" href="#_platfom_specific_features"></a>9.1.4 Platfom Specific Features</h3></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a name="_http_and_api_gateway" href="#_http_and_api_gateway"></a>HTTP and API Gateway</h4></div></div></div><p>AWS has some platform-specific data types, including batching of messages, which is much more efficient than processing each one individually. To make use of these types you can write a function that depends on those types. Or you can rely on Spring to extract the data from the AWS types and convert it to a Spring <code class="literal">Message</code>. To do this you tell AWS that the function is of a specific generic handler type (depending on the AWS service) and provide a bean of type <code class="literal">Function<Message<S>,Message<T>></code>, where <code class="literal">S</code> and <code class="literal">T</code> are your business data types. If there is more than one bean of type <code class="literal">Function</code> you may also need to configure the Spring Boot property <code class="literal">function.name</code> to be the name of the target bean (e.g. use <code class="literal">FUNCTION_NAME</code> as an environment variable).</p><p>The supported AWS services and generic handler types are listed below:</p><div class="informaltable"><table style="border-collapse: collapse;border-top: 0.5pt solid ; border-bottom: 0.5pt solid ; border-left: 0.5pt solid ; border-right: 0.5pt solid ; "><colgroup><col class="col_1"><col class="col_2"><col class="col_3"><col class="col_4"></colgroup><thead><tr><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Service</th><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">AWS Types</th><th style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top">Generic Handler</th><th style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </th></tr></thead><tbody><tr><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p>API Gateway</p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">APIGatewayProxyRequestEvent</code>, <code class="literal">APIGatewayProxyResponseEvent</code></p></td><td style="border-right: 0.5pt solid ; border-bottom: 0.5pt solid ; " align="left" valign="top"><p><code class="literal">org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler</code></p></td><td style="border-bottom: 0.5pt solid ; " align="left" valign="top"> </td></tr><tr><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>Kinesis</p></td><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>KinesisEvent</p></td><td style="border-right: 0.5pt solid ; " align="left" valign="top"><p>org.springframework.cloud.function.adapter.aws.SpringBootKinesisEventHandler</p></td><td style="" align="left" valign="top"> </td></tr></tbody></table></div><p>For example, to deploy behind an API Gateway, use <code class="literal">--handler org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler</code> in your AWS command line (in via the UI) and define a <code class="literal">@Bean</code> of type <code class="literal">Function<Message<Foo>,Message<Bar>></code> where <code class="literal">Foo</code> and <code class="literal">Bar</code> are POJO types (the data will be marshalled and unmarshalled by AWS using Jackson).</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_azure_functions" href="#_azure_functions"></a>9.2 Azure Functions</h2></div></div></div><p>The <a class="link" href="https://azure.microsoft.com" target="_top">Azure</a> adapter bootstraps a Spring Cloud Function context and channels function calls from the Azure framework into the user functions, using Spring Boot configuration where necessary. Azure Functions has quite a unique, but invasive programming model, involving annotations in user code that are specific to the platform. The Spring Cloud Function Azure adapter trades the convenience of these annotations for portability of the function implementations. Instead of using the annotations you have to write some JSON by hand (at least for now) to guide the platform to call the right methods in the adapter.</p><p>This project provides an adapter layer for a Spring Cloud Function application onto Azure.
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You can write an app with a single <code class="literal">@Bean</code> of type <code class="literal">Function</code> and it will be deployable in Azure if you get the JAR file laid out right.</p><p>The adapter has a generic HTTP request handler that you can use optionally.
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There is a <code class="literal">AzureSpringBootRequestHandler</code> which you must extend, and provide the input and output types as type parameters (enabling Azure to inspect the class and do the JSON conversions itself).</p><p>If your app has more than one <code class="literal">@Bean</code> of type <code class="literal">Function</code> etc. then you can choose the one to use by configuring <code class="literal">function.name</code>.
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The functions are extracted from the Spring Cloud <code class="literal">FunctionCatalog</code>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_notes_on_jar_layout_2" href="#_notes_on_jar_layout_2"></a>9.2.1 Notes on JAR Layout</h3></div></div></div><p>You don’t need the Spring Cloud Function Web at runtime in Azure, so you need to exclude this before you create the JAR you deploy to Azure.
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A function application on Azure has to be shaded, but a Spring Boot standalone application does not, so you can run the same app using 2 separate jars (as per the sample here).
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The sample app creates the shaded jar file, with an <code class="literal">azure</code> classifier for deploying in Azure.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_json_configuration" href="#_json_configuration"></a>9.2.2 JSON Configuration</h3></div></div></div><p>The Azure tooling needs to find some JSON configuration files to tell it how to deploy and integrate the function (e.g. which Java class to use as the entry point, and which triggers to use). Those files can be created with the Maven plugin for a non-Spring function, but the tooling doesn’t work yet with the adapter in its current form. There is an example <code class="literal">function.json</code> in the sample which hooks the function up as an HTTP endpoint:</p><pre class="screen">{
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"scriptFile" : "../function-sample-azure-1.0.0.RELEASE-azure.jar",
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"entryPoint" : "example.FooHandler.execute",
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"bindings" : [ {
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"type" : "httpTrigger",
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"name" : "foo",
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"direction" : "in",
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"authLevel" : "anonymous",
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"methods" : [ "get", "post" ]
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}, {
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"type" : "http",
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"name" : "$return",
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"direction" : "out"
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} ],
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"disabled" : false
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}</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_build" href="#_build"></a>9.2.3 Build</h3></div></div></div><pre class="screen">./mvnw -U clean package</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_running_the_sample" href="#_running_the_sample"></a>9.2.4 Running the sample</h3></div></div></div><p>You can run the sample locally, just like the other Spring Cloud Function samples:</p><p></p><p></p><p>and <code class="literal">curl -H "Content-Type: text/plain" localhost:8080/function -d '{"value": "hello foobar"}'</code>.</p><p>You will need the <code class="literal">az</code> CLI app and some node.js fu (see <a class="link" href="https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven" target="_top">https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-first-java-maven</a> for more detail). To deploy the function on Azure runtime:</p><pre class="screen">$ az login
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$ mvn azure-functions:deploy</pre><p>On another terminal try this: <code class="literal">curl <a class="link" href="https://<azure-function-url-from-the-log>/api/uppercase" target="_top">https://<azure-function-url-from-the-log>/api/uppercase</a> -d '{"value": "hello foobar!"}'</code>. Please ensure that you use the right URL for the function above. Alternatively you can test the function in the Azure Dashboard UI (click on the function name, go to the right hand side and click "Test" and to the bottom right, "Run").</p><p>The input type for the function in the Azure sample is a Foo with a single property called "value". So you need this to test it with something like below:</p><pre class="screen">{
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"value": "foobar"
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}</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_apache_openwhisk" href="#_apache_openwhisk"></a>9.3 Apache Openwhisk</h2></div></div></div><p>The <a class="link" href="https://openwhisk.apache.org/" target="_top">OpenWhisk</a> adapter is in the form of an executable jar that can be used in a a docker image to be deployed to Openwhisk. The platform works in request-response mode, listening on port 8080 on a specific endpoint, so the adapter is a simple Spring MVC application.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_quick_start" href="#_quick_start"></a>9.3.1 Quick Start</h3></div></div></div><p>Implement a POF (be sure to use the <code class="literal">functions</code> package):</p><pre class="screen">package functions;
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import java.util.function.Function;
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public class Uppercase implements Function<String, String> {
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public String apply(String input) {
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return input.toUpperCase();
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}
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}</pre><p>Install it into your local Maven repository:</p><pre class="screen">./mvnw clean install</pre><p>Create a <code class="literal">function.properties</code> file that provides its Maven coordinates. For example:</p><pre class="screen">dependencies.function: com.example:pof:0.0.1-SNAPSHOT</pre><p>Copy the openwhisk runner JAR to the working directory (same directory as the properties file):</p><pre class="screen">cp spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk/target/spring-cloud-function-adapter-openwhisk-1.0.0.RELEASE.jar runner.jar</pre><p>Generate a m2 repo from the <code class="literal">--thin.dryrun</code> of the runner JAR with the above properties file:</p><pre class="screen">java -jar -Dthin.root=m2 runner.jar --thin.name=function --thin.dryrun</pre><p>Use the following Dockerfile:</p><pre class="screen">FROM openjdk:8-jdk-alpine
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VOLUME /tmp
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COPY m2 /m2
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ADD runner.jar .
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ADD function.properties .
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ENV JAVA_OPTS=""
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ENTRYPOINT [ "java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "runner.jar", "--thin.root=/m2", "--thin.name=function", "--function.name=uppercase"]
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EXPOSE 8080</pre><div class="blockquote"><blockquote class="blockquote"><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>you could use a Spring Cloud Function app, instead of just a jar with a POF in it, in which case you would have to change the way the app runs in the container so that it picks up the main class as a source file. For example, you could change the <code class="literal">ENTRYPOINT</code> above and add <code class="literal">--spring.main.sources=com.example.SampleApplication</code>.</p></td></tr></table></div></blockquote></div><p>Build the Docker image:</p><pre class="screen">docker build -t [username/appname] .</pre><p>Push the Docker image:</p><pre class="screen">docker push [username/appname]</pre><p>Use the OpenWhisk CLI (e.g. after <code class="literal">vagrant ssh</code>) to create the action:</p><pre class="screen">wsk action create example --docker [username/appname]</pre><p>Invoke the action:</p><pre class="screen">wsk action invoke example --result --param payload foo
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{
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"result": "FOO"
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}</pre></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__dynamic_compilation.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top">8. Dynamic Compilation </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-function.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html> |