Make it easier to just use Boot’s dependency management with Gradle

Closes gh-11059

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/managing-dependencies.adoc

@@ -39,6 +39,48 @@ be done with care.
 
 
 
+[[managing-dependencies-using-in-isolation]]
+=== Using Spring Boot's dependency management in isolation
+
+Spring Boot's dependency management can be used in a project without applying Spring
+Boot's plugin to that project. The `SpringBootPlugin` class provides a `BOM_COORDINATES`
+constant that can be used to import the bom without having to know its group ID,
+artifact ID, or version.
+
+First, configure the project to depend on the Spring Boot plugin but do not apply it:
+
+ifeval::["{version-type}" == "RELEASE"]
+----
+include::../gradle/managing-dependencies/depend-on-plugin-release.gradle[]
+----
+endif::[]
+ifeval::["{version-type}" == "MILESTONE"]
+[source,groovy,indent=0,subs="verbatim,attributes"]
+----
+include::../gradle/managing-dependencies/depend-on-plugin-milestone.gradle[]
+----
+endif::[]
+ifeval::["{version-type}" == "SNAPSHOT"]
+[source,groovy,indent=0,subs="verbatim,attributes"]
+----
+include::../gradle/managing-dependencies/depend-on-plugin-snapshot.gradle[]
+----
+endif::[]
+
+The Spring Boot plugin's dependency on the dependency management plugin means that you
+can use the dependency management plugin without having to declare a dependency on it.
+This also means that you will automatically use the same version of the dependency
+management plugin as Spring Boot uses.
+
+Apply the dependency management plugin and then configure it to import Spring Boot's bom:
+
+[source,groovy,indent=0,subs="verbatim,attributes"]
+----
+include::../gradle/managing-dependencies/configure-bom.gradle[tags=configure-bom]
+----
+
+
+
 [[managing-dependencies-learning-more]]
 === Learning more
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/getting-started/apply-plugin-snapshot.gradle

@@ -4,7 +4,7 @@ buildscript {
 	}
 
 	dependencies {
-		classpath files(pluginClasspath.split(','))
+		classpath 'org.springframework.boot:spring-boot-gradle-plugin:{version}'
 	}
 }
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/managing-dependencies/configure-bom.gradle

@@ -0,0 +1,35 @@
+buildscript {
+	dependencies {
+		classpath files(pluginClasspath.split(','))
+	}
+}
+
+plugins {
+	id 'java'
+}
+
+apply plugin: 'io.spring.dependency-management'
+
+dependencyManagement {
+	resolutionStrategy {
+		eachDependency {
+			if (it.requested.group == 'org.springframework.boot') {
+				it.useVersion project.bootVersion
+			}
+		}
+	}
+}
+
+repositories {
+	mavenLocal()
+}
+
+// tag::configure-bom[]
+apply plugin: 'io.spring.dependency-management'
+
+dependencyManagement {
+	imports {
+		mavenBom org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES
+	}
+}
+// end::configure-bom[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/managing-dependencies/depend-on-plugin-milestone.gradle

@@ -0,0 +1,9 @@
+buildscript {
+	repositories {
+		maven { url 'https://repo.spring.io/libs-milestone' }
+	}
+
+	dependencies {
+		classpath 'org.springframework.boot:spring-boot-gradle-plugin:{version}'
+	}
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/managing-dependencies/depend-on-plugin-release.gradle

@@ -0,0 +1,3 @@
+plugins {
+	id 'org.springframework.boot' version '{version}' apply false
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/gradle/managing-dependencies/depend-on-plugin-snapshot.gradle

@@ -0,0 +1,9 @@
+buildscript {
+	repositories {
+		maven { url 'https://repo.spring.io/libs-snapshot' }
+	}
+
+	dependencies {
+		classpath 'org.springframework.boot:spring-boot-gradle-plugin:{version}'
+	}
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/DependencyManagementPluginAction.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -16,14 +16,6 @@
 
 package org.springframework.boot.gradle.plugin;
 
-import java.io.File;
-import java.io.IOException;
-import java.net.JarURLConnection;
-import java.net.URL;
-import java.net.URLConnection;
-import java.util.jar.Attributes;
-import java.util.jar.JarFile;
-
 import io.spring.gradle.dependencymanagement.DependencyManagementPlugin;
 import io.spring.gradle.dependencymanagement.dsl.DependencyManagementExtension;
 import org.gradle.api.Action;
@@ -38,15 +30,11 @@ import org.gradle.api.Project;
  */
 final class DependencyManagementPluginAction implements PluginApplicationAction {
 
-	private static final String SPRING_BOOT_VERSION = determineSpringBootVersion();
-
-	private static final String SPRING_BOOT_BOM = "org.springframework.boot:spring-boot-dependencies:"
-			+ SPRING_BOOT_VERSION;
-
 	@Override
 	public void execute(Project project) {
 		project.getExtensions().findByType(DependencyManagementExtension.class)
-				.imports((importsHandler) -> importsHandler.mavenBom(SPRING_BOOT_BOM));
+				.imports((importsHandler) -> importsHandler
+						.mavenBom(SpringBootPlugin.BOM_COORDINATES));
 	}
 
 	@Override
@@ -54,32 +42,4 @@ final class DependencyManagementPluginAction implements PluginApplicationAction
 		return DependencyManagementPlugin.class;
 	}
 
-	private static String determineSpringBootVersion() {
-		String implementationVersion = DependencyManagementPluginAction.class.getPackage()
-				.getImplementationVersion();
-		if (implementationVersion != null) {
-			return implementationVersion;
-		}
-		URL codeSourceLocation = DependencyManagementPluginAction.class
-				.getProtectionDomain().getCodeSource().getLocation();
-		try {
-			URLConnection connection = codeSourceLocation.openConnection();
-			if (connection instanceof JarURLConnection) {
-				return getImplementationVersion(
-						((JarURLConnection) connection).getJarFile());
-			}
-			try (JarFile jarFile = new JarFile(new File(codeSourceLocation.toURI()))) {
-				return getImplementationVersion(jarFile);
-			}
-		}
-		catch (Exception ex) {
-			return null;
-		}
-	}
-
-	private static String getImplementationVersion(JarFile jarFile) throws IOException {
-		return jarFile.getManifest().getMainAttributes()
-				.getValue(Attributes.Name.IMPLEMENTATION_VERSION);
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/SpringBootPlugin.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -16,8 +16,15 @@
 
 package org.springframework.boot.gradle.plugin;
 
+import java.io.File;
+import java.io.IOException;
+import java.net.JarURLConnection;
+import java.net.URL;
+import java.net.URLConnection;
 import java.util.Arrays;
 import java.util.List;
+import java.util.jar.Attributes;
+import java.util.jar.JarFile;
 
 import org.gradle.api.GradleException;
 import org.gradle.api.Plugin;
@@ -38,6 +45,8 @@ import org.springframework.boot.gradle.tasks.bundling.BootWar;
  */
 public class SpringBootPlugin implements Plugin<Project> {
 
+	private static final String SPRING_BOOT_VERSION = determineSpringBootVersion();
+
 	/**
 	 * The name of the {@link Configuration} that contains Spring Boot archives.
 	 * @since 2.0.0
@@ -58,6 +67,13 @@ public class SpringBootPlugin implements Plugin<Project> {
 	 */
 	public static final String BOOT_WAR_TASK_NAME = "bootWar";
 
+	/**
+	 * The coordinates {@code (group:name:version)} of the
+	 * {@code spring-boot-dependencies} bom.
+	 */
+	public static final String BOM_COORDINATES = "org.springframework.boot:spring-boot-dependencies:"
+			+ SPRING_BOOT_VERSION;
+
 	@Override
 	public void apply(Project project) {
 		verifyGradleVersion();
@@ -110,4 +126,32 @@ public class SpringBootPlugin implements Plugin<Project> {
 				(buildResult) -> unresolvedDependenciesAnalyzer.buildFinished(project));
 	}
 
+	private static String determineSpringBootVersion() {
+		String implementationVersion = DependencyManagementPluginAction.class.getPackage()
+				.getImplementationVersion();
+		if (implementationVersion != null) {
+			return implementationVersion;
+		}
+		URL codeSourceLocation = DependencyManagementPluginAction.class
+				.getProtectionDomain().getCodeSource().getLocation();
+		try {
+			URLConnection connection = codeSourceLocation.openConnection();
+			if (connection instanceof JarURLConnection) {
+				return getImplementationVersion(
+						((JarURLConnection) connection).getJarFile());
+			}
+			try (JarFile jarFile = new JarFile(new File(codeSourceLocation.toURI()))) {
+				return getImplementationVersion(jarFile);
+			}
+		}
+		catch (Exception ex) {
+			return null;
+		}
+	}
+
+	private static String getImplementationVersion(JarFile jarFile) throws IOException {
+		return jarFile.getManifest().getMainAttributes()
+				.getValue(Attributes.Name.IMPLEMENTATION_VERSION);
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/ManagingDependenciesDocumentationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -47,4 +47,12 @@ public class ManagingDependenciesDocumentationTests {
 				.build("slf4jVersion").getOutput()).contains("1.7.20");
 	}
 
+	@Test
+	public void dependencyManagementInIsolation() {
+		assertThat(this.gradleBuild
+				.script("src/main/gradle/managing-dependencies/configure-bom.gradle")
+				.build("dependencyManagement").getOutput())
+						.contains("org.springframework.boot:spring-boot-starter ");
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/plugin/OnlyDependencyManagementIntegrationTests.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2012-2018 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.gradle.plugin;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.boot.gradle.junit.GradleCompatibilitySuite;
+import org.springframework.boot.gradle.testkit.GradleBuild;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for configuring a project to only use Spring Boot's dependency
+ * management.
+ *
+ * @author Andy Wilkinson
+ */
+@RunWith(GradleCompatibilitySuite.class)
+public class OnlyDependencyManagementIntegrationTests {
+
+	@Rule
+	public GradleBuild gradleBuild;
+
+	@Test
+	public void dependencyManagementCanBeConfiguredUsingCoordinatesConstant() {
+		assertThat(this.gradleBuild.build("dependencyManagement").getOutput())
+				.contains("org.springframework.boot:spring-boot-starter ");
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/OnlyDependencyManagementIntegrationTests.gradle

@@ -0,0 +1,25 @@
+buildscript {
+	dependencies {
+		classpath files(pluginClasspath.split(','))
+	}
+}
+
+apply plugin: 'io.spring.dependency-management'
+apply plugin: 'java'
+
+repositories {
+	mavenLocal()
+}
+
+dependencyManagement {
+	resolutionStrategy {
+		eachDependency {
+			if (it.requested.group == 'org.springframework.boot') {
+				it.useVersion project.bootVersion
+			}
+		}
+	}
+	imports {
+		mavenBom org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES
+	}
+}