Java 9 long classpath support to enable deterministic class loading order

jib-core/src/main/java/com/google/cloud/tools/jib/api/JavaContainerBuilder.java

@@ -65,7 +65,8 @@ public enum LayerType {
     PROJECT_DEPENDENCIES("project dependencies"),
     RESOURCES("resources"),
     CLASSES("classes"),
-    EXTRA_FILES("extra files");
+    EXTRA_FILES("extra files"),
+    JVM_ARG_FILES("jvm arg files");
 
     private final String name;
 

jib-gradle-plugin/CHANGELOG.md

@@ -9,6 +9,8 @@ All notable changes to this project will be documented in this file.
 
 ### Changed
 
+- Jib now creates an additional layer that contains two small text files: `/app/jib-classpath-file` and `/app/jib-main-class-file`. They hold, respectively, the final Java runtime classpath and the main class computed by Jib that are suitable for app execution on JVM. For example, with Java 9+, setting the container entrypoint to `java --class-path @/app/jib-classpath-file @/app/jib-main-class-file` will work to start the app. (This is basically the default entrypoint set by Jib when the entrypoint is not explicitly configured by the user.) The files are always generated whether Java 8 or 9+, or whether `jib.container.entrypoint` is explicitly configured. The files can be helpful especially when setting a custom entrypoint for a shell script that needs to get the classpath and the main class computed by Jib, or for [AppCDS](https://github.com/GoogleContainerTools/jib/issues/2471). ([#3280](https://github.com/GoogleContainerTools/jib/pull/3280))
+- For Java 9+ apps, the default Java runtime classpath explicitly lists all the app dependencies, preserving the dependency loading order declared by Gradle. This is done by changing the default entrypoint to use the new classpath JVM argument file (basically `java -cp @/app/jib-classpath-file`). As such, `jib.container.expandClasspathDependencies` takes no effect for Java 9+. ([#3280](https://github.com/GoogleContainerTools/jib/pull/3280))
 - Timestamps of file entries in a tarball built with `jibBuildTar` are set to the epoch, making the tarball reproducible. ([#3158](https://github.com/GoogleContainerTools/jib/issues/3158))
 
 ### Fixed

jib-gradle-plugin/src/integration-test/java/com/google/cloud/tools/jib/gradle/GradleLayerConfigurationIntegrationTest.java

@@ -18,7 +18,6 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
-import com.google.common.collect.ImmutableList;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -27,7 +26,6 @@
 import java.util.zip.GZIPInputStream;
 import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
 import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
-import org.junit.Assert;
 import org.junit.ClassRule;
 import org.junit.Test;
 
@@ -46,11 +44,12 @@ public void testGradleLayerConfiguration_configurationName() throws IOException
 
     // the expected order is:
     // no base image layers (scratch)
-    // classes (0)
-    // resources (1)
-    // dependencies (2)
+    // jvm arg files (0)
+    // classes (1)
+    // resources (2)
+    // dependencies (3)
     // verify dependencies
-    List<String> dependencies = layers.get(2);
+    List<String> dependencies = layers.get(3);
     assertThat(dependencies).containsExactly("app/", "app/libs/", "app/libs/dependency2").inOrder();
   }
 
@@ -59,18 +58,20 @@ public void testGradleLayerConfiguration_configurationName_prioritizeSystemPrope
       throws IOException {
     configTestProject.build(
         "jibBuildTar",
+        "--stacktrace",
         "-Djib.configurationName=otherConfiguration",
         "-b=build-configuration.gradle");
     Path jibTar = configTestProject.getProjectRoot().resolve("build/jib-image.tar");
     List<List<String>> layers = getLayers(jibTar);
 
     // the expected order is:
     // no base image layers (scratch)
-    // classes (0)
-    // resources (1)
-    // dependencies (2)
+    // jvm arg files (0)
+    // classes (1)
+    // resources (2)
+    // dependencies (3)
     // verify dependencies
-    List<String> dependencies = layers.get(2);
+    List<String> dependencies = layers.get(3);
     assertThat(dependencies).containsExactly("app/", "app/libs/", "app/libs/dependency3").inOrder();
   }
 
@@ -82,57 +83,53 @@ public void testGradleLayerConfiguration_multiModule() throws IOException {
 
     List<List<String>> layers = getLayers(jibTar);
 
-    Assert.assertEquals(6, layers.size());
+    assertThat(layers).hasSize(7);
 
     // the expected order is:
     // no base image layers (scratch)
     // extra-files (0)
-    // classes (1)
-    // resources (2)
-    // project dependencies (3)
-    // snapshot dependencies (4)
-    // dependencies (5)
+    // jvm arg files (1)
+    // classes (2)
+    // resources (3)
+    // project dependencies (4)
+    // snapshot dependencies (5)
+    // dependencies (6)
 
     // verify dependencies
-    List<String> dependencies = layers.get(5);
-    List<String> expectedDependencies =
-        ImmutableList.of("app/", "app/libs/", "app/libs/dependency-1.0.0.jar");
-    Assert.assertEquals(expectedDependencies, dependencies);
+    assertThat(layers.get(6))
+        .containsExactly("app/", "app/libs/", "app/libs/dependency-1.0.0.jar")
+        .inOrder();
 
     // verify snapshot dependencies
-    List<String> snapshotDependencies = layers.get(4);
-    List<String> expectedSnapshotDependencies =
-        ImmutableList.of("app/", "app/libs/", "app/libs/dependencyX-1.0.0-SNAPSHOT.jar");
-    Assert.assertEquals(expectedSnapshotDependencies, snapshotDependencies);
+    assertThat(layers.get(5))
+        .containsExactly("app/", "app/libs/", "app/libs/dependencyX-1.0.0-SNAPSHOT.jar")
+        .inOrder();
 
     // verify project dependencies
-    List<String> projectDependencies = layers.get(3);
-    List<String> expectedProjectDependencies =
-        ImmutableList.of("app/", "app/libs/", "app/libs/lib.jar");
-    Assert.assertEquals(expectedProjectDependencies, projectDependencies);
+    assertThat(layers.get(4)).containsExactly("app/", "app/libs/", "app/libs/lib.jar").inOrder();
 
     // verify resources
-    List<String> resources = layers.get(2);
-    List<String> expectedResources =
-        ImmutableList.of(
-            "app/", "app/resources/", "app/resources/resource1.txt", "app/resources/resource2.txt");
-    Assert.assertEquals(expectedResources, resources);
+    assertThat(layers.get(3))
+        .containsExactly(
+            "app/", "app/resources/", "app/resources/resource1.txt", "app/resources/resource2.txt")
+        .inOrder();
 
     // verify classes
-    List<String> classes = layers.get(1);
-    List<String> expectedClasses =
-        ImmutableList.of(
+    assertThat(layers.get(2))
+        .containsExactly(
             "app/",
             "app/classes/",
             "app/classes/com/",
             "app/classes/com/test/",
             "app/classes/com/test/HelloWorld.class");
-    Assert.assertEquals(expectedClasses, classes);
+
+    // verify jvm arg files
+    assertThat(layers.get(1))
+        .containsExactly("app/", "app/jib-classpath-file", "app/jib-main-class-file")
+        .inOrder();
 
     // verify extra files
-    List<String> extraFiles = layers.get(0);
-    List<String> expectedExtraFiles = ImmutableList.of("extra-file");
-    Assert.assertEquals(expectedExtraFiles, extraFiles);
+    assertThat(layers.get(0)).containsExactly("extra-file");
   }
 
   @Test
@@ -143,22 +140,27 @@ public void testGradleLayerConfiguration_simpleModule() throws IOException {
 
     List<List<String>> layers = getLayers(jibTar);
 
-    Assert.assertEquals(1, layers.size());
+    assertThat(layers).hasSize(2);
 
     // the expected order is:
     // no base image layers (scratch)
-    // classes (0)
+    // jvm arg files (0)
+    // classes (1)
 
     // verify classes
-    List<String> classes = layers.get(0);
-    List<String> expectedClasses =
-        ImmutableList.of(
+    assertThat(layers.get(1))
+        .containsExactly(
             "app/",
             "app/classes/",
             "app/classes/com/",
             "app/classes/com/test/",
-            "app/classes/com/test/HelloWorld.class");
-    Assert.assertEquals(expectedClasses, classes);
+            "app/classes/com/test/HelloWorld.class")
+        .inOrder();
+
+    // verify jvm arg files
+    assertThat(layers.get(0))
+        .containsExactly("app/", "app/jib-classpath-file", "app/jib-main-class-file")
+        .inOrder();
   }
 
   // returns all files in layers (*.tar.gz) in a image tar

jib-gradle-plugin/src/integration-test/java/com/google/cloud/tools/jib/gradle/SingleProjectIntegrationTest.java

@@ -210,7 +210,7 @@ public void testBuild_simple()
     assertThat(getEntrypoint(targetImage))
         .isEqualTo(
             "[java -cp /d1:/d2:/app/resources:/app/classes:/app/libs/* com.test.HelloWorld]");
-    assertThat(getLayerSize(targetImage)).isEqualTo(9);
+    assertThat(getLayerSize(targetImage)).isEqualTo(10);
   }
 
   @Test
@@ -306,7 +306,7 @@ public void testDockerDaemon_simple_multipleExtraDirectories()
             + "1970-01-01T00:00:01Z\n1970-01-01T00:00:01Z\n",
         JibRunHelper.buildToDockerDaemonAndRun(
             simpleTestProject, targetImage, "build-extra-dirs.gradle"));
-    assertThat(getLayerSize(targetImage)).isEqualTo(10); // one more than usual
+    assertThat(getLayerSize(targetImage)).isEqualTo(11); // one more than usual
   }
 
   @Test
@@ -318,7 +318,7 @@ public void testDockerDaemon_simple_multipleExtraDirectoriesWithAlternativeConfi
             + "1970-01-01T00:00:01Z\n1970-01-01T00:00:01Z\n",
         JibRunHelper.buildToDockerDaemonAndRun(
             simpleTestProject, targetImage, "build-extra-dirs2.gradle"));
-    assertThat(getLayerSize(targetImage)).isEqualTo(10); // one more than usual
+    assertThat(getLayerSize(targetImage)).isEqualTo(11); // one more than usual
   }
 
   @Test
@@ -330,7 +330,7 @@ public void testDockerDaemon_simple_multipleExtraDirectoriesWithClosure()
             + "1970-01-01T00:00:01Z\n1970-01-01T00:00:01Z\nbaz\n1970-01-01T00:00:01Z\n",
         JibRunHelper.buildToDockerDaemonAndRun(
             simpleTestProject, targetImage, "build-extra-dirs3.gradle"));
-    assertThat(getLayerSize(targetImage)).isEqualTo(10); // one more than usual
+    assertThat(getLayerSize(targetImage)).isEqualTo(11); // one more than usual
   }
 
   @Test

jib-maven-plugin/CHANGELOG.md

@@ -9,6 +9,8 @@ All notable changes to this project will be documented in this file.
 
 ### Changed
 
+- Jib now creates an additional layer that contains two small text files: `/app/jib-classpath-file` and `/app/jib-main-class-file`. They hold, respectively, the final Java runtime classpath and the main class computed by Jib that are suitable for app execution on JVM. For example, with Java 9+, setting the container entrypoint to `java --class-path @/app/jib-classpath-file @/app/jib-main-class-file` will work to start the app. (This is basically the default entrypoint set by Jib when the entrypoint is not explicitly configured by the user.) The files are always generated whether Java 8 or 9+, or whether `jib.container.entrypoint` is explicitly configured. The files can be helpful especially when setting a custom entrypoint for a shell script that needs to get the classpath and the main class computed by Jib, or for [AppCDS](https://github.com/GoogleContainerTools/jib/issues/2471). ([#3280](https://github.com/GoogleContainerTools/jib/pull/3280))
+- For Java 9+ apps, the default Java runtime classpath explicitly lists all the app dependencies, preserving the dependency loading order declared by Maven. This is done by changing the default entrypoint to use the new classpath JVM argument file (basically `java -cp @/app/jib-classpath-file`). As such, `<container><expandClasspathDependencies>` takes no effect for Java 9+. ([#3280](https://github.com/GoogleContainerTools/jib/pull/3280))
 - Timestamps of file entries in a tarball built with `jib:buildTar` are set to the epoch, making the tarball reproducible. ([#3158](https://github.com/GoogleContainerTools/jib/issues/3158))
 
 ### Fixed