Fail on bootBuildImage with launch script

This commit adds a check to the support code for the Gradle plugin
bootBuildImage task to ensure that the jar file that will be passed
to a builder is readable and has a valid directory. This prevents a
situation where the jar file cannot be read because it is prepended
with a launch script, and the builder does not receive any files to
process.

Notes have also been added to the Gradle plugin documentation to warn
against using a bootJar launchScript configuration and bootBuildImage
together, as well as caveats about launchScript that match the Maven
plugin documentation.

Fixes gh-22223

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/build/BuildRequest.java

@@ -235,7 +235,6 @@ public boolean isVerboseLogging() {
 	 * @return a new build request instance
 	 */
 	public static BuildRequest forJarFile(File jarFile) {
-		assertJarFile(jarFile);
 		return forJarFile(ImageReference.forJarFile(jarFile).inTaggedForm(), jarFile);
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/io/ZipFileTarArchive.java

@@ -35,6 +35,7 @@
  * Adapter class to convert a ZIP file to a {@link TarArchive}.
  *
  * @author Phillip Webb
+ * @author Scott Frederick
  * @since 2.3.0
  */
 public class ZipFileTarArchive implements TarArchive {
@@ -54,6 +55,7 @@ public class ZipFileTarArchive implements TarArchive {
 	public ZipFileTarArchive(File zip, Owner owner) {
 		Assert.notNull(zip, "Zip must not be null");
 		Assert.notNull(owner, "Owner must not be null");
+		assertArchiveHasEntries(zip);
 		this.zip = zip;
 		this.owner = owner;
 	}
@@ -72,6 +74,16 @@ public void writeTo(OutputStream outputStream) throws IOException {
 		tar.finish();
 	}
 
+	private void assertArchiveHasEntries(File jarFile) {
+		try (ZipFile zipFile = new ZipFile(jarFile)) {
+			Assert.state(zipFile.getEntries().hasMoreElements(), "File '" + jarFile.toString()
+					+ "' is not compatible with buildpacks; ensure jar file is valid and launch script is not enabled");
+		}
+		catch (IOException ex) {
+			throw new IllegalStateException("File is not readable", ex);
+		}
+	}
+
 	private void copy(ZipArchiveEntry zipEntry, InputStream zip, TarArchiveOutputStream tar) throws IOException {
 		TarArchiveEntry tarEntry = convert(zipEntry);
 		tar.putArchiveEntry(tarEntry);

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/asciidoc/packaging-oci-image.adoc

@@ -4,7 +4,8 @@ The plugin can create an https://github.com/opencontainers/image-spec[OCI image]
 Images can be built using the `bootBuildImage` task.
 The task is automatically created when the `java` plugin is applied and is an instance of {boot-build-image-javadoc}[`BootBuildImage`].
 
-
+NOTE: The `bootBuildImage` task can not be used with a <<packaging-executable-configuring-launch-script, fully executable Spring Boot archive>> that includes a launch script.
+Disable launch script configuration in the `bootJar` task when building a jar file that is intended to be used with `bootBuildImage`.
 
 [[build-image-docker-daemon]]
 === Docker Daemon

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/asciidoc/packaging.adoc

@@ -201,6 +201,10 @@ Spring Boot provides support for fully executable archives.
 An archive is made fully executable by prepending a shell script that knows how to launch the application.
 On Unix-like platforms, this launch script allows the archive to be run directly like any other executable or to be installed as a service.
 
+NOTE: Currently, some tools do not accept this format so you may not always be able to use this technique.
+For example, `jar -xf` may silently fail to extract a jar or war that has been made fully-executable.
+It is recommended that you only enable this option if you intend to execute it directly, rather than running it with `java -jar`, deploying it to a servlet container, or including it in an OCI image.
+
 To use this feature, the inclusion of the launch script must be enabled:
 
 [source,groovy,indent=0,subs="verbatim,attributes",role="primary"]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests.java

@@ -126,6 +126,15 @@ void buildsImageWithCommandLineOptions() throws IOException {
 		}
 	}
 
+	@TestTemplate
+	void failsWithLaunchScript() {
+		writeMainClass();
+		writeLongNameResource();
+		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage");
+		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.FAILED);
+		assertThat(result.getOutput()).contains("not compatible with buildpacks");
+	}
+
 	@TestTemplate
 	void failsWithBuilderError() {
 		writeMainClass();

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests-failsWithLaunchScript.gradle

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+bootJar {
+	launchScript()
+}