Support lazy configuration for mainClass and jvmFlags properties of ContainerParameters

jib-gradle-plugin/README.md

@@ -255,9 +255,9 @@ Property | Type | Default | Description
 `expandClasspathDependencies` | `boolean` | `false` | <ul><li>Java 8 *or* Jib < 3.1: When set to true, does not use a wildcard (for example, `/app/lib/*`) for dependency JARs in the default Java runtime classpath but instead enumerates the JARs. Has the effect of preserving the classpath loading order as defined by the Gradle project.</li><li>Java >= 9 *and* Jib >= 3.1: The option has no effect. Jib *always* enumerates the dependency JARs. This is achieved by [creating and using an argument file](#custom-container-entrypoint) for the `--class-path` JVM argument.</li></ul>
 `filesModificationTime` | `String` | `EPOCH_PLUS_SECOND` | Sets the modification time (last modified time) of files in the image put by Jib. (Note that this does not set the image creation time, which can be set using `jib.container.creationTime`.) The value should either be `EPOCH_PLUS_SECOND` to set the timestamps to Epoch + 1 second (default behavior), or an ISO 8601 date-time parsable with [`DateTimeFormatter.ISO_DATE_TIME`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/time/format/DateTimeFormatter.html#ISO_DATE_TIME) such as `2019-07-15T10:15:30+09:00` or `2011-12-03T22:42:05Z`. The value can also be initialized [lazily](https://docs.gradle.org/current/userguide/lazy_configuration.html) with a provider.
 `format` | `String` | `Docker` | Use `OCI` to build an [OCI container image](https://www.opencontainers.org/).
-`jvmFlags` | `List<String>` | *None* | Additional flags to pass into the JVM when running your application.
+`jvmFlags` | `List<String>` | *None* | Additional flags to pass into the JVM when running your application. The value can also be initialized [lazily](https://docs.gradle.org/current/userguide/lazy_configuration.html) with a provider.
 `labels` | `Map<String, String>` | *None* | Key-value pairs for applying image metadata (similar to Docker's [LABEL](https://docs.docker.com/engine/reference/builder/#label) instruction).
-`mainClass` | `String` | *Inferred*\*\* | The main class to launch your application from.
+`mainClass` | `String` | *Inferred*\*\* | The main class to launch your application from. The value can also be initialized [lazily](https://docs.gradle.org/current/userguide/lazy_configuration.html) with a provider.
 `ports` | `List<String>` | *None* | Ports that the container exposes at runtime (similar to Docker's [EXPOSE](https://docs.docker.com/engine/reference/builder/#expose) instruction).
 `user` | `String` | *None* | The user and group to run the container as. The value can be a username or UID along with an optional groupname or GID. The following are all valid: `user`, `uid`, `user:group`, `uid:gid`, `uid:group`, `user:gid`.
 `volumes` | `List<String>` | *None* | Specifies a list of mount points on the container.

jib-gradle-plugin/src/main/java/com/google/cloud/tools/jib/gradle/ContainerParameters.java

@@ -26,8 +26,10 @@
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 import org.gradle.api.model.ObjectFactory;
+import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.MapProperty;
 import org.gradle.api.provider.Property;
+import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Optional;
 
@@ -37,12 +39,12 @@
  */
 public class ContainerParameters {
 
-  private List<String> jvmFlags = Collections.emptyList();
+  private final ListProperty<String> jvmFlags;
   private Map<String, String> environment = Collections.emptyMap();
   @Nullable private List<String> entrypoint;
   private List<String> extraClasspath = Collections.emptyList();
   private boolean expandClasspathDependencies;
-  @Nullable private String mainClass;
+  private final Property<String> mainClass;
   @Nullable private List<String> args;
   private ImageFormat format = ImageFormat.Docker;
   private List<String> ports = Collections.emptyList();
@@ -59,6 +61,8 @@ public ContainerParameters(ObjectFactory objectFactory) {
     labels = objectFactory.mapProperty(String.class, String.class).empty();
     filesModificationTime = objectFactory.property(String.class).convention("EPOCH_PLUS_SECOND");
     creationTime = objectFactory.property(String.class).convention("EPOCH");
+    mainClass = objectFactory.property(String.class);
+    jvmFlags = objectFactory.listProperty(String.class);
   }
 
   @Input
@@ -83,15 +87,19 @@ public void setEntrypoint(String entrypoint) {
   @Input
   @Optional
   public List<String> getJvmFlags() {
-    if (System.getProperty(PropertyNames.CONTAINER_JVM_FLAGS) != null) {
-      return ConfigurationPropertyValidator.parseListProperty(
-          System.getProperty(PropertyNames.CONTAINER_JVM_FLAGS));
+    String jvmFlagsSystemProperty = System.getProperty(PropertyNames.CONTAINER_JVM_FLAGS);
+    if (jvmFlagsSystemProperty != null) {
+      return ConfigurationPropertyValidator.parseListProperty(jvmFlagsSystemProperty);
     }
-    return jvmFlags;
+    return jvmFlags.getOrElse(Collections.emptyList());
   }
 
   public void setJvmFlags(List<String> jvmFlags) {
-    this.jvmFlags = jvmFlags;
+    this.jvmFlags.set(jvmFlags);
+  }
+
+  public void setJvmFlags(Provider<List<String>> jvmFlags) {
+    this.jvmFlags.set(jvmFlags);
   }
 
   @Input
@@ -138,14 +146,19 @@ public void setExpandClasspathDependencies(boolean expand) {
   @Nullable
   @Optional
   public String getMainClass() {
-    if (System.getProperty(PropertyNames.CONTAINER_MAIN_CLASS) != null) {
-      return System.getProperty(PropertyNames.CONTAINER_MAIN_CLASS);
+    String mainClassProperty = System.getProperty(PropertyNames.CONTAINER_MAIN_CLASS);
+    if (mainClassProperty != null) {
+      return mainClassProperty;
     }
-    return mainClass;
+    return mainClass.getOrNull();
   }
 
   public void setMainClass(String mainClass) {
-    this.mainClass = mainClass;
+    this.mainClass.set(mainClass);
+  }
+
+  public void setMainClass(Provider<String> mainClass) {
+    this.mainClass.set(mainClass);
   }
 
   @Input

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

@@ -407,6 +407,18 @@ public void testLazyEvalForContainerCreationAndFileModificationTimes() {
     assertThat(output).contains("filesModificationTime=2022-07-19T11:23:42Z");
   }
 
+  @Test
+  public void testLazyEvalForMainClass() {
+    BuildResult showLabels = testProject.build("showMainClass");
+    assertThat(showLabels.getOutput()).contains("mainClass value updated");
+  }
+
+  @Test
+  public void testLazyEvalForJvmFlags() {
+    BuildResult showLabels = testProject.build("showJvmFlags");
+    assertThat(showLabels.getOutput()).contains("jvmFlags value [updated]");
+  }
+
   private Project createProject(String... plugins) {
     Project project =
         ProjectBuilder.builder().withProjectDir(testProjectRoot.getRoot()).withName("root").build();

jib-gradle-plugin/src/test/resources/gradle/projects/lazy-evaluation/build.gradle

@@ -39,6 +39,8 @@ jib {
         }
         creationTime = project.provider { project.ext.jibCreationTime }
         filesModificationTime = project.provider { project.ext.jibFilesModificationTime }
+        mainClass = project.provider { project.ext.value }
+        jvmFlags = project.provider { [project.ext.value] }
     }
     extraDirectories {
         paths = project.provider { ['src/main/' + project.ext.value + '-custom-extra-dir'] }
@@ -64,3 +66,13 @@ tasks.register('showtimes') {
     prop = project.extensions.jib.container.filesModificationTime.get()
     println('filesModificationTime=' + prop)
 }
+
+tasks.register('showMainClass') {
+    String prop = project.extensions.jib.container.mainClass
+    println('mainClass value ' + prop)
+}
+
+tasks.register('showJvmFlags') {
+    List<String> prop = project.extensions.jib.container.jvmFlags
+    println('jvmFlags value ' + prop)
+}