Fixes validate tag nullpointerexception. (#127)

* Fixes validate tag nullpointerexception.

* Fixes ImageReference string form logging.

Author: coollog

CHANGELOG.md

@@ -7,6 +7,7 @@ All notable changes to this project will be documented in this file.
 ### Changed
 
 ### Fixed
+- Null tag validation generating NullPointerException ([#125](https://github.com/google/jib/issues/125))
 
 ## 0.1.3
 ### Added

jib-core/src/main/java/com/google/cloud/tools/jib/image/ImageReference.java

@@ -33,6 +33,7 @@ public class ImageReference {
 
   private static final String DOCKER_HUB_REGISTRY = "registry.hub.docker.com";
   private static final String DEFAULT_TAG = "latest";
+  private static final String LIBRARY_REPOSITORY_PREFIX = "library/";
 
   /**
    * Matches all sequences of alphanumeric characters possibly separated by any number of dashes in
@@ -112,7 +113,7 @@ public static ImageReference parse(String reference) throws InvalidImageReferenc
      * See https://docs.docker.com/engine/reference/commandline/pull/#pull-an-image-from-docker-hub
      */
     if (DOCKER_HUB_REGISTRY.equals(registry) && repository.indexOf('/') < 0) {
-      repository = "library/" + repository;
+      repository = LIBRARY_REPOSITORY_PREFIX + repository;
     }
 
     if (!Strings.isNullOrEmpty(tag)) {
@@ -132,10 +133,10 @@ public static ImageReference parse(String reference) throws InvalidImageReferenc
   /** Builds an image reference from a registry, repository, and tag. */
   public static ImageReference of(
       @Nullable String registry, String repository, @Nullable String tag) {
-    if (registry == null) {
+    if (Strings.isNullOrEmpty(registry)) {
       registry = DOCKER_HUB_REGISTRY;
     }
-    if (tag == null) {
+    if (Strings.isNullOrEmpty(tag)) {
       tag = DEFAULT_TAG;
     }
     return new ImageReference(registry, repository, tag);
@@ -178,4 +179,30 @@ public String getRepository() {
   public String getTag() {
     return tag;
   }
+
+  /** @return the image reference in Docker-readable format (inverse of {@link #parse}) */
+  @Override
+  public String toString() {
+    StringBuilder referenceString = new StringBuilder();
+
+    if (!DOCKER_HUB_REGISTRY.equals(registry)) {
+      // Use registry and repository if not Docker Hub.
+      referenceString.append(registry).append('/').append(repository);
+
+    } else if (repository.startsWith(LIBRARY_REPOSITORY_PREFIX)) {
+      // If Docker Hub and repository has 'library/' prefix, remove the 'library/' prefix.
+      referenceString.append(repository.substring(LIBRARY_REPOSITORY_PREFIX.length()));
+
+    } else {
+      // Use just repository if Docker Hub.
+      referenceString.append(repository);
+    }
+
+    // Use tag if not the default tag.
+    if (!DEFAULT_TAG.equals(tag)) {
+      referenceString.append(':').append(tag);
+    }
+
+    return referenceString.toString();
+  }
 }

jib-core/src/test/java/com/google/cloud/tools/jib/image/ImageReferenceTest.java

@@ -120,6 +120,20 @@ public void testOf_smoke() {
         expectedRepository, ImageReference.of(null, expectedRepository, null).getRepository());
   }
 
+  @Test
+  public void testToString() {
+    Assert.assertEquals("someimage", ImageReference.of(null, "someimage", null).toString());
+    Assert.assertEquals("someimage", ImageReference.of("", "someimage", "").toString());
+    Assert.assertEquals(
+        "someotherimage", ImageReference.of(null, "library/someotherimage", null).toString());
+    Assert.assertEquals(
+        "someregistry/someotherimage",
+        ImageReference.of("someregistry", "someotherimage", null).toString());
+    Assert.assertEquals(
+        "anotherregistry/anotherimage:sometag",
+        ImageReference.of("anotherregistry", "anotherimage", "sometag").toString());
+  }
+
   private void verifyParse(String registry, String repository, String tagSeparator, String tag)
       throws InvalidImageReferenceException {
     // Gets the expected parsed components.

jib-maven-plugin/src/main/java/com/google/cloud/tools/jib/maven/BuildImageMojo.java

@@ -34,6 +34,7 @@
 import com.google.cloud.tools.jib.registry.RegistryUnauthorizedException;
 import com.google.cloud.tools.jib.registry.credentials.RegistryCredentials;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -153,10 +154,11 @@ public void execute() throws MojoExecutionException, MojoFailureException {
     RegistryCredentials mavenSettingsCredentials =
         RegistryCredentials.from("Maven settings", registryCredentials);
 
+    ImageReference targetImageReference = ImageReference.of(registry, repository, tag);
     BuildConfiguration buildConfiguration =
         BuildConfiguration.builder(new MavenBuildLogger(getLog()))
             .setBaseImage(baseImage)
-            .setTargetImage(ImageReference.of(registry, repository, tag))
+            .setTargetImage(targetImageReference)
             .setCredentialHelperNames(credHelpers)
             .setKnownRegistryCredentials(mavenSettingsCredentials)
             .setMainClass(mainClass)
@@ -178,7 +180,7 @@ public void execute() throws MojoExecutionException, MojoFailureException {
     }
 
     getLog().info("");
-    getLog().info("Pushing image as " + registry + "/" + repository + ":" + tag);
+    getLog().info("Pushing image as " + targetImageReference);
     getLog().info("");
 
     // TODO: Instead of disabling logging, have authentication credentials be provided
@@ -192,7 +194,7 @@ public void execute() throws MojoExecutionException, MojoFailureException {
     buildImage(new BuildImageSteps(buildConfiguration, sourceFilesConfiguration, cacheDirectory));
 
     getLog().info("");
-    getLog().info("Built and pushed image as " + registry + "/" + repository + ":" + tag);
+    getLog().info("Built and pushed image as " + targetImageReference);
     getLog().info("");
   }
 
@@ -252,22 +254,24 @@ private Authorization getRegistryCredentialsFromSettings(String registry) {
   /** Checks validity of plugin parameters. */
   private void validateParameters() throws MojoFailureException {
     // Validates 'registry'.
-    if (!ImageReference.isValidRegistry(registry)) {
+    if (!Strings.isNullOrEmpty(registry) && !ImageReference.isValidRegistry(registry)) {
       getLog().error("Invalid format for 'registry'");
     }
     // Validates 'repository'.
     if (!ImageReference.isValidRepository(repository)) {
       getLog().error("Invalid format for 'repository'");
     }
     // Validates 'tag'.
-    if (!ImageReference.isValidTag(tag)) {
-      getLog().error("Invalid format for 'tag'");
-    }
+    if (!Strings.isNullOrEmpty(tag)) {
+      if (!ImageReference.isValidTag(tag)) {
+        getLog().error("Invalid format for 'tag'");
+      }
 
-    // 'tag' must not contain backslashes.
-    if (tag.indexOf('/') >= 0) {
-      getLog().error("'tag' cannot contain backslashes");
-      throw new MojoFailureException("Invalid configuration parameters");
+      // 'tag' must not contain backslashes.
+      if (tag.indexOf('/') >= 0) {
+        getLog().error("'tag' cannot contain backslashes");
+        throw new MojoFailureException("Invalid configuration parameters");
+      }
     }
   }