Add support for configuring Aether via settings.xml

Previously, Aether's configuration was largely hard-coded making it
impossible to configure a mirror, provide credentials for accessing
a repository, etc.

This commit adds support for configuring Aether via Maven's
settings.xml file. The support is optional and must be enabled by
grabbing spring-boot-maven-settings in an init script. The Aether
instance that's used when running the application will then be
configured using settings.xml. The settings file is expected to be
found in ${user.home}/.m2/settings.xml.

The configuration of the following items is currently supported:

 - Offline
 - Proxies
 - Mirrors
 - Server authentication
 - Local repository location

If the support is not enabled, settings.xml does not exist, or
settings.xml does not configure certain things then sensible defaults
are applied.

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/GroovyCompiler.java

@@ -22,6 +22,7 @@ import groovy.lang.GroovyClassLoader.ClassCollector;
 import java.io.File;
 import java.io.IOException;
 import java.lang.reflect.Field;
+import java.net.URL;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -42,11 +43,9 @@ import org.codehaus.groovy.control.customizers.CompilationCustomizer;
 import org.codehaus.groovy.control.customizers.ImportCustomizer;
 import org.codehaus.groovy.transform.ASTTransformation;
 import org.codehaus.groovy.transform.ASTTransformationVisitor;
-import org.eclipse.aether.repository.RemoteRepository;
-import org.eclipse.aether.repository.RepositoryPolicy;
 import org.springframework.boot.cli.compiler.grape.AetherGrapeEngine;
+import org.springframework.boot.cli.compiler.grape.AetherGrapeEngineFactory;
 import org.springframework.boot.cli.compiler.grape.GrapeEngineInstaller;
-import org.springframework.boot.cli.compiler.grape.RepositoryConfiguration;
 import org.springframework.boot.cli.compiler.transformation.DependencyAutoConfigurationTransformation;
 import org.springframework.boot.cli.compiler.transformation.GroovyBeansTransformation;
 import org.springframework.boot.cli.compiler.transformation.ResolveDependencyCoordinatesTransformation;
@@ -92,15 +91,17 @@ public class GroovyCompiler {
 		this.loader = createLoader(configuration);
 
 		this.coordinatesResolver = new PropertiesArtifactCoordinatesResolver(this.loader);
-		GrapeEngineInstaller.install(new AetherGrapeEngine(this.loader,
-				createRepositories(configuration.getRepositoryConfiguration())));
+
+		AetherGrapeEngine grapeEngine = AetherGrapeEngineFactory.create(this.loader,
+				configuration.getRepositoryConfiguration());
+
+		GrapeEngineInstaller.install(grapeEngine);
 
 		this.loader.getConfiguration().addCompilationCustomizers(
 				new CompilerAutoConfigureCustomizer());
 		if (configuration.isAutoconfigure()) {
-			this.compilerAutoConfigurations = ServiceLoader.load(
-					CompilerAutoConfiguration.class,
-					GroovyCompiler.class.getClassLoader());
+			this.compilerAutoConfigurations = ServiceLoader
+					.load(CompilerAutoConfiguration.class);
 		}
 		else {
 			this.compilerAutoConfigurations = Collections.emptySet();
@@ -122,31 +123,29 @@ public class GroovyCompiler {
 
 	private ExtendedGroovyClassLoader createLoader(
 			GroovyCompilerConfiguration configuration) {
+
 		ExtendedGroovyClassLoader loader = new ExtendedGroovyClassLoader(
 				configuration.getScope());
+
+		for (URL url : getExistingUrls()) {
+			loader.addURL(url);
+		}
+
 		for (String classpath : configuration.getClasspath()) {
 			loader.addClasspath(classpath);
 		}
+
 		return loader;
 	}
 
-	private List<RemoteRepository> createRepositories(
-			List<RepositoryConfiguration> repositoryConfigurations) {
-		List<RemoteRepository> repositories = new ArrayList<RemoteRepository>(
-				repositoryConfigurations.size());
-		for (RepositoryConfiguration repositoryConfiguration : repositoryConfigurations) {
-			RemoteRepository.Builder builder = new RemoteRepository.Builder(
-					repositoryConfiguration.getName(), "default", repositoryConfiguration
-							.getUri().toASCIIString());
-
-			if (!repositoryConfiguration.getSnapshotsEnabled()) {
-				builder.setSnapshotPolicy(new RepositoryPolicy(false,
-						RepositoryPolicy.UPDATE_POLICY_NEVER,
-						RepositoryPolicy.CHECKSUM_POLICY_IGNORE));
-			}
-			repositories.add(builder.build());
+	private URL[] getExistingUrls() {
+		ClassLoader tccl = Thread.currentThread().getContextClassLoader();
+		if (tccl instanceof ExtendedGroovyClassLoader) {
+			return ((ExtendedGroovyClassLoader) tccl).getURLs();
+		}
+		else {
+			return new URL[0];
 		}
-		return repositories;
 	}
 
 	public void addCompilationCustomizers(CompilationCustomizer... customizers) {

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/AetherGrapeEngine.java

@@ -29,34 +29,20 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
-import org.apache.maven.repository.internal.MavenRepositorySystemUtils;
 import org.eclipse.aether.DefaultRepositorySystemSession;
 import org.eclipse.aether.RepositorySystem;
-import org.eclipse.aether.RepositorySystemSession;
 import org.eclipse.aether.artifact.Artifact;
 import org.eclipse.aether.artifact.DefaultArtifact;
 import org.eclipse.aether.collection.CollectRequest;
-import org.eclipse.aether.connector.basic.BasicRepositoryConnectorFactory;
 import org.eclipse.aether.graph.Dependency;
 import org.eclipse.aether.graph.Exclusion;
-import org.eclipse.aether.impl.DefaultServiceLocator;
-import org.eclipse.aether.internal.impl.DefaultRepositorySystem;
-import org.eclipse.aether.repository.LocalRepository;
-import org.eclipse.aether.repository.LocalRepositoryManager;
-import org.eclipse.aether.repository.ProxySelector;
 import org.eclipse.aether.repository.RemoteRepository;
 import org.eclipse.aether.resolution.ArtifactResolutionException;
 import org.eclipse.aether.resolution.ArtifactResult;
 import org.eclipse.aether.resolution.DependencyRequest;
 import org.eclipse.aether.resolution.DependencyResult;
-import org.eclipse.aether.spi.connector.RepositoryConnectorFactory;
-import org.eclipse.aether.spi.connector.transport.TransporterFactory;
-import org.eclipse.aether.spi.locator.ServiceLocator;
-import org.eclipse.aether.transport.file.FileTransporterFactory;
-import org.eclipse.aether.transport.http.HttpTransporterFactory;
 import org.eclipse.aether.util.artifact.JavaScopes;
 import org.eclipse.aether.util.filter.DependencyFilterUtils;
-import org.springframework.util.StringUtils;
 
 /**
  * A {@link GrapeEngine} implementation that uses <a
@@ -76,25 +62,20 @@ public class AetherGrapeEngine implements GrapeEngine {
 
 	private final GroovyClassLoader classLoader;
 
-	private final RepositorySystemSession session;
+	private final DefaultRepositorySystemSession session;
 
 	private final RepositorySystem repositorySystem;
 
 	private final List<RemoteRepository> repositories;
 
-	private ProxySelector proxySelector = new JreProxySelector();
-
 	public AetherGrapeEngine(GroovyClassLoader classLoader,
+			RepositorySystem repositorySystem,
+			DefaultRepositorySystemSession repositorySystemSession,
 			List<RemoteRepository> remoteRepositories) {
 		this.classLoader = classLoader;
-		this.repositorySystem = createServiceLocator().getService(RepositorySystem.class);
-		DefaultRepositorySystemSession session = MavenRepositorySystemUtils.newSession();
-		LocalRepository localRepository = new LocalRepository(getM2RepoDirectory());
-		LocalRepositoryManager localRepositoryManager = this.repositorySystem
-				.newLocalRepositoryManager(session, localRepository);
-		session.setLocalRepositoryManager(localRepositoryManager);
-		session.setProxySelector(this.proxySelector);
-		this.session = session;
+		this.repositorySystem = repositorySystem;
+		this.session = repositorySystemSession;
+
 		this.repositories = new ArrayList<RemoteRepository>();
 		List<RemoteRepository> remotes = new ArrayList<RemoteRepository>(
 				remoteRepositories);
@@ -102,37 +83,8 @@ public class AetherGrapeEngine implements GrapeEngine {
 		for (RemoteRepository repository : remotes) {
 			addRepository(repository);
 		}
-		this.progressReporter = getProgressReporter(session);
-	}
 
-	private ServiceLocator createServiceLocator() {
-		DefaultServiceLocator locator = MavenRepositorySystemUtils.newServiceLocator();
-		locator.addService(RepositorySystem.class, DefaultRepositorySystem.class);
-		locator.addService(RepositoryConnectorFactory.class,
-				BasicRepositoryConnectorFactory.class);
-		locator.addService(TransporterFactory.class, HttpTransporterFactory.class);
-		locator.addService(TransporterFactory.class, FileTransporterFactory.class);
-		return locator;
-	}
-
-	private File getM2RepoDirectory() {
-		return new File(getM2HomeDirectory(), "repository");
-	}
-
-	private File getM2HomeDirectory() {
-		String grapeRoot = System.getProperty("grape.root");
-		if (StringUtils.hasLength(grapeRoot)) {
-			return new File(grapeRoot);
-		}
-		return getDefaultM2HomeDirectory();
-	}
-
-	private File getDefaultM2HomeDirectory() {
-		String mavenRoot = System.getProperty("maven.home");
-		if (StringUtils.hasLength(mavenRoot)) {
-			return new File(mavenRoot);
-		}
-		return new File(System.getProperty("user.home"), ".m2");
+		this.progressReporter = getProgressReporter(this.session);
 	}
 
 	private ProgressReporter getProgressReporter(DefaultRepositorySystemSession session) {
@@ -268,7 +220,7 @@ public class AetherGrapeEngine implements GrapeEngine {
 		}
 		if (repository.getProxy() == null) {
 			RemoteRepository.Builder builder = new RemoteRepository.Builder(repository);
-			builder.setProxy(this.proxySelector.getProxy(repository));
+			builder.setProxy(this.session.getProxySelector().getProxy(repository));
 			repository = builder.build();
 		}
 		this.repositories.add(0, repository);

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/AetherGrapeEngineFactory.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 org.springframework.boot.cli.compiler.grape;
+
+import groovy.lang.GroovyClassLoader;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.ServiceLoader;
+
+import org.apache.maven.repository.internal.MavenRepositorySystemUtils;
+import org.eclipse.aether.DefaultRepositorySystemSession;
+import org.eclipse.aether.RepositorySystem;
+import org.eclipse.aether.connector.basic.BasicRepositoryConnectorFactory;
+import org.eclipse.aether.impl.DefaultServiceLocator;
+import org.eclipse.aether.internal.impl.DefaultRepositorySystem;
+import org.eclipse.aether.repository.RemoteRepository;
+import org.eclipse.aether.repository.RepositoryPolicy;
+import org.eclipse.aether.spi.connector.RepositoryConnectorFactory;
+import org.eclipse.aether.spi.connector.transport.TransporterFactory;
+import org.eclipse.aether.spi.locator.ServiceLocator;
+import org.eclipse.aether.transport.file.FileTransporterFactory;
+import org.eclipse.aether.transport.http.HttpTransporterFactory;
+
+/**
+ * Utility class to create a pre-configured {@link AetherGrapeEngine}.
+ * 
+ * @author Andy Wilkinson
+ */
+public abstract class AetherGrapeEngineFactory {
+
+	public static AetherGrapeEngine create(GroovyClassLoader classLoader,
+			List<RepositoryConfiguration> repositoryConfigurations) {
+
+		RepositorySystem repositorySystem = createServiceLocator().getService(
+				RepositorySystem.class);
+
+		DefaultRepositorySystemSession repositorySystemSession = MavenRepositorySystemUtils
+				.newSession();
+
+		ServiceLoader<RepositorySystemSessionAutoConfiguration> autoConfigurations = ServiceLoader
+				.load(RepositorySystemSessionAutoConfiguration.class);
+
+		for (RepositorySystemSessionAutoConfiguration autoConfiguration : autoConfigurations) {
+			autoConfiguration.apply(repositorySystemSession, repositorySystem);
+		}
+
+		new DefaultRepositorySystemSessionAutoConfiguration().apply(
+				repositorySystemSession, repositorySystem);
+
+		return new AetherGrapeEngine(classLoader, repositorySystem,
+				repositorySystemSession, createRepositories(repositoryConfigurations));
+	}
+
+	private static ServiceLocator createServiceLocator() {
+		DefaultServiceLocator locator = MavenRepositorySystemUtils.newServiceLocator();
+		locator.addService(RepositorySystem.class, DefaultRepositorySystem.class);
+		locator.addService(RepositoryConnectorFactory.class,
+				BasicRepositoryConnectorFactory.class);
+		locator.addService(TransporterFactory.class, HttpTransporterFactory.class);
+		locator.addService(TransporterFactory.class, FileTransporterFactory.class);
+		return locator;
+	}
+
+	private static List<RemoteRepository> createRepositories(
+			List<RepositoryConfiguration> repositoryConfigurations) {
+		List<RemoteRepository> repositories = new ArrayList<RemoteRepository>(
+				repositoryConfigurations.size());
+		for (RepositoryConfiguration repositoryConfiguration : repositoryConfigurations) {
+			RemoteRepository.Builder builder = new RemoteRepository.Builder(
+					repositoryConfiguration.getName(), "default", repositoryConfiguration
+							.getUri().toASCIIString());
+
+			if (!repositoryConfiguration.getSnapshotsEnabled()) {
+				builder.setSnapshotPolicy(new RepositoryPolicy(false,
+						RepositoryPolicy.UPDATE_POLICY_NEVER,
+						RepositoryPolicy.CHECKSUM_POLICY_IGNORE));
+			}
+			repositories.add(builder.build());
+		}
+		return repositories;
+	}
+}

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/DefaultRepositorySystemSessionAutoConfiguration.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 org.springframework.boot.cli.compiler.grape;
+
+import java.io.File;
+
+import org.eclipse.aether.DefaultRepositorySystemSession;
+import org.eclipse.aether.RepositorySystem;
+import org.eclipse.aether.repository.LocalRepository;
+import org.eclipse.aether.repository.LocalRepositoryManager;
+import org.springframework.util.StringUtils;
+
+/**
+ * A {@link RepositorySystemSessionAutoConfiguration} that, in the absence of any
+ * configuration, applies sensible defaults.
+ * 
+ * @author Andy Wilkinson
+ */
+public class DefaultRepositorySystemSessionAutoConfiguration implements
+		RepositorySystemSessionAutoConfiguration {
+
+	@Override
+	public void apply(DefaultRepositorySystemSession session,
+			RepositorySystem repositorySystem) {
+
+		if (session.getLocalRepositoryManager() == null) {
+			LocalRepository localRepository = new LocalRepository(getM2RepoDirectory());
+			LocalRepositoryManager localRepositoryManager = repositorySystem
+					.newLocalRepositoryManager(session, localRepository);
+			session.setLocalRepositoryManager(localRepositoryManager);
+		}
+
+		if (session.getProxySelector() == null) {
+			session.setProxySelector(new JreProxySelector());
+		}
+	}
+
+	private File getM2RepoDirectory() {
+		return new File(getM2HomeDirectory(), "repository");
+	}
+
+	private File getM2HomeDirectory() {
+		String grapeRoot = System.getProperty("grape.root");
+		if (StringUtils.hasLength(grapeRoot)) {
+			return new File(grapeRoot);
+		}
+		return getDefaultM2HomeDirectory();
+	}
+
+	private File getDefaultM2HomeDirectory() {
+		String mavenRoot = System.getProperty("maven.home");
+		if (StringUtils.hasLength(mavenRoot)) {
+			return new File(mavenRoot);
+		}
+		return new File(System.getProperty("user.home"), ".m2");
+	}
+}

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/RepositorySystemSessionAutoConfiguration.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 org.springframework.boot.cli.compiler.grape;
+
+import org.eclipse.aether.DefaultRepositorySystemSession;
+import org.eclipse.aether.RepositorySystem;
+
+/**
+ * Strategy that can be used to apply some auto-configuration during the installation of
+ * an {@link AetherGrapeEngine}.
+ * 
+ * @author Andy Wilkinson
+ */
+public interface RepositorySystemSessionAutoConfiguration {
+
+	/**
+	 * Apply the configuration
+	 */
+	void apply(DefaultRepositorySystemSession session, RepositorySystem repositorySystem);
+
+}