GH-555 Add missing maven resource support to function deployer

Resolves #555

docs/src/main/asciidoc/spring-cloud-function.adoc

@@ -353,7 +353,12 @@ The standard entry point is to add `spring-cloud-function-deployer` to the class
 ```
 
 
-At a minimum the user has to provide a `spring.cloud.function.location` which is a URL or resource location for the archive containing the functions. It can optionally use a `maven:` prefix to locate the artifact via a dependency lookup (see `FunctionProperties` for complete details). A Spring Boot application is bootstrapped from the jar file, using the `MANIFEST.MF` to locate a start class, so that a standard Spring Boot fat jar works well, for example. If the target jar can be launched successfully then the result is a function registered in the main application's `FunctionCatalog`. The registered function can be applied by code in the main application, even though it was created in an isolated class loader (by deault).
+At a minimum the user has to provide a `spring.cloud.function.location` which is a URL or resource location for the archive containing 
+the functions. It can optionally use a `maven:` prefix to locate the artifact via a dependency lookup (see `FunctionProperties` 
+for complete details). A Spring Boot application is bootstrapped from the jar file, using the `MANIFEST.MF` to locate a start class, so 
+that a standard Spring Boot fat jar works well, for example. If the target jar can be launched successfully then the result is a function 
+registered in the main application's `FunctionCatalog`. The registered function can be applied by code in the main application, even though 
+it was created in an isolated class loader (by deault).
 
 Here is the example of deploying a JAR which contains an 'uppercase' function and invoking it .
 
@@ -373,6 +378,39 @@ public class DeployFunctionDemo {
 }
 ```
 
+And here is the example using Maven URI (taken from one of the tests in `FunctionDeployerTests`):
+
+```java
+@SpringBootApplication
+public class DeployFunctionDemo {
+
+	public static void main(String[] args) {
+		String[] args = new String[] {
+				"--spring.cloud.function.location=maven://oz.demo:demo-uppercase:0.0.1-SNAPSHOT",
+				"--spring.cloud.function.function-class=oz.demo.uppercase.MyFunction" };
+
+		ApplicationContext context = SpringApplication.run(DeployerApplication.class, args);
+		FunctionCatalog catalog = context.getBean(FunctionCatalog.class);
+		Function<String, String> function = catalog.lookup("myFunction");
+
+		assertThat(function.apply("bob")).isEqualTo("BOB");
+	}
+}
+```
+
+Keep in mind that Maven resource such as local and remote repositories, user, password and more are resolved using default MavenProperties which 
+effectively use local defaults and will work for majority of cases. However if you need to customize you can simply provide a bean of type 
+`MavenProperties` where you can set additional properties (see example below).
+
+```java
+@Bean
+public MavenProperties mavenProperties() {
+	MavenProperties properties = new MavenProperties();
+	properties.setLocalRepository("target/it/");
+	return properties;
+}
+```
+
 === Supported Packaging Scenarios 
 
 Currently Spring Cloud Function supports several packaging scenarios to give you the most flexibility when it comes to deploying functions.

spring-cloud-function-deployer/mavenrepo/oz/demo/demo-stream/0.0.1-SNAPSHOT/demo-stream-0.0.1-SNAPSHOT.pom

@@ -0,0 +1,107 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.3.0.RELEASE</version>
+<!--         <version>2.2.6.RELEASE</version> -->
+        <relativePath /> 
+    </parent>
+    <groupId>oz.demo</groupId>
+    <artifactId>demo-stream</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>demo-stream</name>
+    <description>Demo project for Spring Boot</description>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <spring-cloud.version>Hoxton.SR5</spring-cloud.version>
+    </properties>
+
+    <dependencies>
+<!--         <dependency> -->
+<!--             <groupId>org.springframework.boot</groupId> -->
+<!--             <artifactId>spring-boot-starter-web</artifactId> -->
+<!--         </dependency> -->
+        
+<!--         <dependency>  -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-starter-function-web</artifactId> -->
+<!--             <version>3.1.0-SNAPSHOT</version> -->
+<!--         </dependency> -->
+<!--          <dependency>  -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-function-rsocket</artifactId> -->
+<!--             <version>3.1.0-SNAPSHOT</version> -->
+<!--         </dependency> -->
+<!--         <dependency>  -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-function-web</artifactId> -->
+<!--             <version>3.1.0-SNAPSHOT</version> -->
+<!--         </dependency> -->
+<!--         <dependency>  -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-function-web</artifactId> -->
+<!--             <version>3.1.0-SNAPSHOT</version> -->
+<!--         </dependency> -->
+<!--        <dependency> -->
+<!--     		<groupId>org.json</groupId> -->
+<!--     		<artifactId>json</artifactId> -->
+<!--     		<version>20190722</version> -->
+<!-- 		</dependency> -->
+<!-- 		<dependency> -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-function-web</artifactId> -->
+<!--         </dependency> -->
+  
+<!--         <dependency> -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-stream</artifactId> -->
+<!--             <version>3.1.0-SNAPSHOT</version> -->
+<!--         </dependency> -->
+<!--         <dependency> -->
+<!--             <groupId>org.springframework.cloud</groupId> -->
+<!--             <artifactId>spring-cloud-stream-binder-rabbit</artifactId> -->
+<!--              <version>3.1.0-SNAPSHOT</version> -->
+<!--         </dependency> -->
+      
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.junit.vintage</groupId>
+                    <artifactId>junit-vintage-engine</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+    </dependencies>
+
+ 
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.springframework.cloud</groupId>
+                <artifactId>spring-cloud-dependencies</artifactId>
+                <version>${spring-cloud.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+<!--     <build> -->
+<!--         <plugins> -->
+<!--             <plugin> -->
+<!--                 <groupId>org.springframework.boot</groupId> -->
+<!--                 <artifactId>spring-boot-maven-plugin</artifactId> -->
+<!--             </plugin> -->
+<!--         </plugins> -->
+<!--     </build> -->
+
+</project>

spring-cloud-function-deployer/mavenrepo/oz/demo/demo-stream/0.0.1-SNAPSHOT/maven-metadata-local.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<metadata modelVersion="1.1.0">
+  <groupId>oz.demo</groupId>
+  <artifactId>demo-stream</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <versioning>
+    <snapshot>
+      <localCopy>true</localCopy>
+    </snapshot>
+    <lastUpdated>20200721131233</lastUpdated>
+    <snapshotVersions>
+      <snapshotVersion>
+        <extension>jar</extension>
+        <value>0.0.1-SNAPSHOT</value>
+        <updated>20200721131233</updated>
+      </snapshotVersion>
+      <snapshotVersion>
+        <extension>pom</extension>
+        <value>0.0.1-SNAPSHOT</value>
+        <updated>20200721131233</updated>
+      </snapshotVersion>
+    </snapshotVersions>
+  </versioning>
+</metadata>

spring-cloud-function-deployer/mavenrepo/oz/demo/demo-stream/maven-metadata-local.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<metadata>
+  <groupId>oz.demo</groupId>
+  <artifactId>demo-stream</artifactId>
+  <versioning>
+    <versions>
+      <version>0.0.1-SNAPSHOT</version>
+    </versions>
+    <lastUpdated>20200721131233</lastUpdated>
+  </versioning>
+</metadata>

spring-cloud-function-deployer/pom.xml

@@ -30,6 +30,11 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-function-context</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-deployer-resource-maven</artifactId>
+			<version>2.4.0-M1</version>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

spring-cloud-function-deployer/src/main/java/org/springframework/cloud/function/deployer/FunctionDeployerConfiguration.java

@@ -33,6 +33,8 @@ import org.springframework.boot.env.EnvironmentPostProcessor;
 import org.springframework.boot.loader.archive.Archive;
 import org.springframework.boot.loader.archive.ExplodedArchive;
 import org.springframework.boot.loader.archive.JarFileArchive;
+import org.springframework.cloud.deployer.resource.maven.MavenProperties;
+import org.springframework.cloud.deployer.resource.maven.MavenResourceLoader;
 import org.springframework.cloud.function.context.FunctionProperties;
 import org.springframework.cloud.function.context.FunctionRegistry;
 import org.springframework.context.SmartLifecycle;
@@ -42,6 +44,8 @@ import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertiesPropertySource;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -64,13 +68,23 @@ public class FunctionDeployerConfiguration {
 
 	@Bean
 	SmartLifecycle functionArchiveDeployer(FunctionDeployerProperties functionProperties,
-			FunctionRegistry functionRegistry, ApplicationArguments arguments) {
+			FunctionRegistry functionRegistry, ApplicationArguments arguments, @Nullable MavenProperties mavenProperties) {
 
 		ApplicationArguments updatedArguments = this.updateArguments(arguments);
 
 		Archive archive = null;
 		try {
-			File file = new File(functionProperties.getLocation());
+			File file;
+			String location = functionProperties.getLocation();
+			Assert.hasText(location, "`spring.cloud.function.location` property must be defined.");
+			if (location.startsWith("maven://")) {
+				MavenResourceLoader resourceLoader = new MavenResourceLoader(mavenProperties);
+				file = resourceLoader.getResource(location).getFile();
+			}
+			else {
+				file = new File(location);
+			}
+
 			if (!file.exists()) {
 				throw new IllegalStateException("Failed to create archive: " + functionProperties.getLocation() + " does not exist");
 			}

spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/deployer/FunctionDeployerTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.function.deployer;
 
+
+
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
@@ -29,11 +31,14 @@ import reactor.util.function.Tuples;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cloud.deployer.resource.maven.MavenProperties;
 import org.springframework.cloud.function.context.FunctionCatalog;
 import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.support.MessageBuilder;
 
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -48,6 +53,19 @@ public class FunctionDeployerTests {
 		System.clearProperty("spring.cloud.function.definition");
 	}
 
+	@Test
+	public void testWithMavenConfiguration() throws Exception {
+		String[] args = new String[] {
+				"--spring.cloud.function.location=maven://oz.demo:demo-stream:0.0.1-SNAPSHOT",
+				"--spring.cloud.function.function-class=oz.demo.demostream.MyFunction" };
+
+		ApplicationContext context = SpringApplication.run(DeployerApplication.class, args);
+		FunctionCatalog catalog = context.getBean(FunctionCatalog.class);
+		Function<String, String> function = catalog.lookup("myFunction");
+
+		assertThat(function.apply("bob")).isEqualTo("BOB");
+	}
+
 	/*
 	 * Target function `class UpperCaseFunction implements Function<String, String>`
 	 * Main/Start class present, no Spring configuration
@@ -376,5 +394,11 @@ public class FunctionDeployerTests {
 
 	@SpringBootApplication(proxyBeanMethods = false)
 	private static class DeployerApplication {
+		@Bean
+		public MavenProperties mavenProperties() {
+			MavenProperties properties = new MavenProperties();
+			properties.setLocalRepository("mavenrepo/");
+			return properties;
+		}
 	}
 }