Set Spring Boot version in ephemeral builder

This commit adds a `createdBy` structure to the metadata of the ephemeral
builder container image that identifies Spring Boot as the creator of the
image, along with the Spring Boot version.

See gh-20126

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/BuildImageMojo.java

@@ -41,6 +41,7 @@ import org.springframework.boot.buildpack.platform.build.AbstractBuildLog;
 import org.springframework.boot.buildpack.platform.build.BuildLog;
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
 import org.springframework.boot.buildpack.platform.build.Builder;
+import org.springframework.boot.buildpack.platform.build.Creator;
 import org.springframework.boot.buildpack.platform.docker.TotalProgressEvent;
 import org.springframework.boot.buildpack.platform.io.Owner;
 import org.springframework.boot.buildpack.platform.io.TarArchive;
@@ -53,6 +54,7 @@ import org.springframework.util.StringUtils;
  * Package an application into a OCI image using a buildpack.
  *
  * @author Phillip Webb
+ * @author Scott Frederick
  * @since 2.3.0
  */
 @Mojo(name = "build-image", defaultPhase = LifecyclePhase.PACKAGE, requiresProject = true, threadSafe = true,
@@ -124,7 +126,8 @@ public class BuildImageMojo extends AbstractPackagerMojo {
 
 	private BuildRequest getBuildRequest(Libraries libraries) {
 		Function<Owner, TarArchive> content = (owner) -> getApplicationContent(owner, libraries);
-		return ((this.image != null) ? this.image : new Image()).getBuildRequest(this.project.getArtifact(), content);
+		Image image = (this.image != null) ? this.image : new Image();
+		return customize(image.getBuildRequest(this.project.getArtifact(), content));
 	}
 
 	private TarArchive getApplicationContent(Owner owner, Libraries libraries) {
@@ -143,6 +146,14 @@ public class BuildImageMojo extends AbstractPackagerMojo {
 		return new File(this.sourceDirectory, name.toString());
 	}
 
+	private BuildRequest customize(BuildRequest request) {
+		String springBootVersion = VersionExtractor.forClass(BuildImageMojo.class);
+		if (StringUtils.hasText(springBootVersion)) {
+			request = request.withCreator(Creator.withVersion(springBootVersion));
+		}
+		return request;
+	}
+
 	/**
 	 * {@link BuildLog} backed by Mojo logging.
 	 */

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/VersionExtractor.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2012-2020 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
+ *
+ *      https://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.maven;
+
+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;
+
+/**
+ * Extracts version information for a Class.
+ *
+ * @author Andy Wilkinson
+ * @author Scott Frederick
+ */
+final class VersionExtractor {
+
+	private VersionExtractor() {
+	}
+
+	/**
+	 * Return the version information for the provided {@link Class}.
+	 * @param cls the Class to retrieve the version for
+	 * @return the version, or {@code null} if a version can not be extracted
+	 */
+	static String forClass(Class<?> cls) {
+		String implementationVersion = cls.getPackage().getImplementationVersion();
+		if (implementationVersion != null) {
+			return implementationVersion;
+		}
+		URL codeSourceLocation = cls.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);
+	}
+
+}