Spring Cloud Function in Azure

This article outlines the deployment of Spring Cloud Function as a Java Function to Azure Functions, from validation and setup to testing and deployment.

Vignesh Prabhu

Feb. 02, 21 · Tutorial

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This article covers the usage of Spring Cloud Function as a Java Function and deployment to Azure Functions.

Prerequisites

JDK, version 8+.
Apache Maven, version 3 or higher.
Azure Account (free trial would suffice as well).
Azure CLI.
Azure Functions Core Tools.

Validating the Local Environment Setup

Verify Apache Maven version:

    PowerShell
   
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mvn -V

Verify Azure CLI:

    PowerShell
   
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az --version

Verify Azure Function Core tools:

    PowerShell
   
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func -v

Code Setup

Create an empty maven project. Use the below pom.xml and build the project.

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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>
    <groupId>com.demo</groupId>
    <artifactId>demo-springcloud-function</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>Helloworld Spring Function on Azure</name>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <azure.functions.java.library.version>1.4.0</azure.functions.java.library.version>
        <azure.functions.maven.plugin.version>1.3.1</azure.functions.maven.plugin.version>
        <functionResourceGroup>sample-resource-group</functionResourceGroup>
        <functionAppName>helloworld-spring-function</functionAppName>
        <functionAppRegion>westeurope</functionAppRegion>
        <stagingDirectory>${project.build.directory}/azure-functions/${functionAppName}</stagingDirectory>
        <start-class>com.demo.HelloworldApplication</start-class>
        <spring.boot.wrapper.version>1.0.26.RELEASE</spring.boot.wrapper.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-function-adapter-azure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-function-webflux</artifactId>
            <scope>provided</scope>
        </dependency>
        <!-- Test -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>5.7.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.gatling.highcharts</groupId>
            <artifactId>gatling-charts-highcharts</artifactId>
            <version>3.5.0</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-function-dependencies</artifactId>
                <version>3.1.0</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.microsoft.azure.functions</groupId>
                <artifactId>azure-functions-java-library</artifactId>
                <version>${azure.functions.java.library.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
<build>
    <plugins>
        <plugin>
            <groupId>com.microsoft.azure</groupId>
            <artifactId>azure-functions-maven-plugin</artifactId>
            <configuration>
                <appName>${functionAppName}</appName>
                <resourceGroup>${functionResourceGroup}</resourceGroup>
                <appServicePlanName>azure-functions-app-service-plan</appServicePlanName>
                <region>${functionAppRegion}</region>
                <runtime>
                    <os>windows</os>
                </runtime>
                <appSettings>
                    <property>
                        <name>FUNCTIONS_EXTENSION_VERSION</name>
                        <value>~3</value>
                    </property>
                </appSettings>
            </configuration>
            <executions>
                <execution>
                    <id>package-functions</id>
                    <goals>
                        <goal>package</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-resources-plugin</artifactId>
            <executions>
                <execution>
                    <id>copy-resources</id>
                    <phase>package</phase>
                    <goals>
                        <goal>copy-resources</goal>
                    </goals>
                    <configuration>
                        <overwrite>true</overwrite>
                        <outputDirectory>${stagingDirectory}</outputDirectory>
                        <resources>
                            <resource>
                                <directory>${project.basedir}</directory>
                                <includes>
                                    <include>host.json</include>
                                    <include>local.settings.json</include>
                                </includes>
                            </resource>
                        </resources>
                    </configuration>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <executions>
                <execution>
                    <id>copy-dependencies</id>
                    <phase>prepare-package</phase>
                    <goals>
                        <goal>copy-dependencies</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${stagingDirectory}/lib</outputDirectory>
                        <overWriteReleases>false</overWriteReleases>
                        <overWriteSnapshots>false</overWriteSnapshots>
                        <overWriteIfNewer>true</overWriteIfNewer>
                        <includeScope>runtime</includeScope>
                        <excludeArtifactIds>azure-functions-java-library</excludeArtifactIds>
                    </configuration>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <artifactId>maven-clean-plugin</artifactId>
            <version>3.1.0</version>
            <configuration>
                <filesets>
                    <fileset>
                        <directory>obj</directory>
                    </fileset>
                </filesets>
            </configuration>
        </plugin>
    </plugins>
</build>
</project>

      

     

Customize below properties in the pom.xml file as per your application.

<functionAppName> — name of your Azure Function

<functionAppRegion> — name of the Azure region where your Function will be deployed

<functionResourceGroup> — name of the Azure resource group which will be used

In the Project base directory create the following configuration files required by the Azure Functions.

host.json

    JSON
   
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{
  "version": "2.0",
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[1.*, 2.0.0)"
  } 
}

local.settings.json

    JSON
   
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{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "",
    "FUNCTIONS_WORKER_RUNTIME": "java"
  },
  "Host": {
    "LocalHttpPort": 8091,
    "CORS": "*",
    "CORSCredentials": false
  }
}

Create below Model Classes.

Employee.java

    Java
   
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package com.demo.model;
import jdk.nashorn.internal.objects.annotations.Getter;
public class Employee {
    private String name;
    public Employee(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

EmployeeGreeting.java

    Java
   
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package com.demo.model;
public class EmployeeGreeting {
    private String message;
    public EmployeeGreeting(String message) {
        this.message = message;
    }
    public String getMessage() {
        return message;
    }
    public void setMessage(String message) {
        this.message = message;
    }
}

Create the Springboot Application

The welcomeEmployee() function returns a java.util.function.Function and is a Spring bean. It is important that the Azure Functions that we create next will have the same name.

welcomeEmployee

    Java
   
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package com.demo;
import com.demo.model.Employee;
import com.demo.model.EmployeeGreeting;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import java.util.function.Function;
@SpringBootApplication
public class HelloworldApplication {
    public static void main(String[] args) throws Exception {
        SpringApplication.run(HelloworldApplication.class, args);
    }
    @Bean
    public Function<Employee, EmployeeGreeting> welcomeEmployee() {
        return employee -> new EmployeeGreeting("Hello, We welcome you , " + employee.getName());
    }
}

Create the Azure Function

The Java class which is an Azure Function extends the AzureSpringBootRequestHandler, does the link between Azure Functions and Spring Cloud Function. This is what provides the handleRequest() method that is used in its execute() method.
The name of the function, defined with @FunctionName("welcomeEmployee") annotation, is the same as the Spring bean we have configured in the previous step, welcomeEmployee

    Java
   
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package com.demo;
import com.demo.model.Employee;
import com.demo.model.EmployeeGreeting;
import com.microsoft.azure.functions.*;
import com.microsoft.azure.functions.annotation.AuthorizationLevel;
import com.microsoft.azure.functions.annotation.FunctionName;
import com.microsoft.azure.functions.annotation.HttpTrigger;
import org.springframework.cloud.function.adapter.azure.AzureSpringBootRequestHandler;
import java.util.Optional;
public class HelloWorldHandler extends AzureSpringBootRequestHandler<Employee, EmployeeGreeting> {
    @FunctionName("welcomeEmployee")
    public HttpResponseMessage execute(
            @HttpTrigger(name = "request", methods = {HttpMethod.GET, HttpMethod.POST},authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<Employee>> request,ExecutionContext context) {
       
        return request
                .createResponseBuilder(HttpStatus.OK)
                .body(handleRequest(request.getBody().get(), context))
                .header("Content-Type", "application/json")
                .build();
    }
}

Local Testing

Package the application:

    PowerShell
   
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mvn clean package

Run the project locally:

    PowerShell
   
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mvn azure-functions:run

Below will be the output in the console on successful startup:

Successful output in the console

Test the setup using Postman:

Verify setup in Postman

Deployment to Azure Function

In the command line, run the below command and login to the Azure account.

    PowerShell
   
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az login

Deploy to Azure function using below command:

    PowerShell
   
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mvn azure-functions:deploy

Expected console output after above command

Verify the deployment by logging into the Azure Portal:

Azure portal homepage

Test the Azure function by using Postman:

Use Postman to test Azure function

azure Spring Cloud Spring Framework

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