Make intermediate build config available

jib-core/CHANGELOG.md

@@ -5,6 +5,8 @@ All notable changes to this project will be documented in this file.
 
 ### Added
 
+- New method: `JibContainerBuilder#describeContainer` which returns new class: `JibContainerDescription`, containing a selection of information used for the Jib build. ([#2115](https://github.com/GoogleContainerTools/jib/issues/2115))
+
 ### Changed
 
 ### Fixed

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

@@ -22,7 +22,11 @@
 import java.nio.file.attribute.PosixFilePermission;
 import java.util.Set;
 
-/** Represents read/write/execute file permissions for owner, group, and others. */
+/**
+ * Represents read/write/execute file permissions for owner, group, and others.
+ *
+ * <p>This class is immutable and thread-safe.
+ */
 public class FilePermissions {
 
   /** Default permissions for files added to the container. */

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

@@ -477,6 +477,16 @@ public JibContainer containerize(Containerizer containerizer)
     return containerize(containerizer, Executors::newCachedThreadPool);
   }
 
+  /**
+   * Describes the container contents and configuration without actually physically building a
+   * container.
+   *
+   * @return a description of the container being built
+   */
+  public JibContainerDescription describeContainer() {
+    return new JibContainerDescription(layerConfigurations);
+  }
+
   @VisibleForTesting
   JibContainer containerize(
       Containerizer containerizer, Supplier<ExecutorService> defaultExecutorServiceFactory)

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

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2019 Google LLC.
+ *
+ * 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 com.google.cloud.tools.jib.api;
+
+import com.google.cloud.tools.jib.configuration.ContainerConfiguration;
+import com.google.common.collect.ImmutableList;
+import java.util.List;
+
+/**
+ * A class containing the representation of the contents of a container. Currently only exposes
+ * "layers", but can be extended to expose {@link ContainerConfiguration}, {@link ImageReference} of
+ * the base image, or other informational classes.
+ *
+ * <p>This class is immutable and thread-safe.
+ */
+public class JibContainerDescription {
+
+  private final ImmutableList<LayerConfiguration> layers;
+
+  JibContainerDescription(List<LayerConfiguration> layers) {
+    this.layers = ImmutableList.copyOf(layers);
+  }
+
+  /**
+   * Returns a list of "user configured" layers, does *not* include base layer information.
+   *
+   * @return An {@link ImmutableList} of {@link LayerConfiguration}s
+   */
+  public List<LayerConfiguration> getLayers() {
+    return layers;
+  }
+}

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

@@ -23,6 +23,8 @@
 /**
  * Represents an entry in the layer. A layer consists of many entries that can be converted into tar
  * archive entries.
+ *
+ * <p>This class is immutable and thread-safe.
  */
 public class LayerEntry {
 

jib-plugins-common/src/main/java/com/google/cloud/tools/jib/plugins/common/PluginConfigurationProcessor.java

@@ -176,24 +176,12 @@ public static JibBuildRunner createJibBuildRunnerForRegistryImage(
   static JibContainerBuilder processCommonConfiguration(
       RawConfiguration rawConfiguration,
       InferredAuthProvider inferredAuthProvider,
-      ProjectProperties projectProperties,
-      Containerizer containerizer)
-      throws InvalidImageReferenceException, MainClassInferenceException, InvalidAppRootException,
-          IOException, InvalidWorkingDirectoryException, InvalidContainerVolumeException,
-          IncompatibleBaseImageJavaVersionException, NumberFormatException,
-          InvalidContainerizingModeException, InvalidFilesModificationTimeException,
+      ProjectProperties projectProperties)
+      throws InvalidFilesModificationTimeException, InvalidAppRootException,
+          IncompatibleBaseImageJavaVersionException, IOException, InvalidImageReferenceException,
+          InvalidContainerizingModeException, MainClassInferenceException,
+          InvalidContainerVolumeException, InvalidWorkingDirectoryException,
           InvalidCreationTimeException {
-    JibSystemProperties.checkHttpTimeoutProperty();
-    JibSystemProperties.checkProxyPortProperty();
-
-    if (JibSystemProperties.sendCredentialsOverHttp()) {
-      projectProperties.log(
-          LogEvent.warn(
-              "Authentication over HTTP is enabled. It is strongly recommended that you do not "
-                  + "enable this on a public network!"));
-    }
-
-    configureContainerizer(containerizer, rawConfiguration, projectProperties);
 
     // Create and configure JibContainerBuilder
     BiFunction<Path, AbsoluteUnixPath, Instant> modificationTimeProvider =
@@ -240,6 +228,32 @@ static JibContainerBuilder processCommonConfiguration(
     return jibContainerBuilder;
   }
 
+  @VisibleForTesting
+  static JibContainerBuilder processCommonConfiguration(
+      RawConfiguration rawConfiguration,
+      InferredAuthProvider inferredAuthProvider,
+      ProjectProperties projectProperties,
+      Containerizer containerizer)
+      throws InvalidImageReferenceException, MainClassInferenceException, InvalidAppRootException,
+          IOException, InvalidWorkingDirectoryException, InvalidContainerVolumeException,
+          IncompatibleBaseImageJavaVersionException, NumberFormatException,
+          InvalidContainerizingModeException, InvalidFilesModificationTimeException,
+          InvalidCreationTimeException {
+    JibSystemProperties.checkHttpTimeoutProperty();
+    JibSystemProperties.checkProxyPortProperty();
+
+    if (JibSystemProperties.sendCredentialsOverHttp()) {
+      projectProperties.log(
+          LogEvent.warn(
+              "Authentication over HTTP is enabled. It is strongly recommended that you do not "
+                  + "enable this on a public network!"));
+    }
+
+    configureContainerizer(containerizer, rawConfiguration, projectProperties);
+
+    return processCommonConfiguration(rawConfiguration, inferredAuthProvider, projectProperties);
+  }
+
   /**
    * Returns a {@link JavaContainerBuilder} with the correctly parsed base image configuration.
    *