Separate tag in the Docker API tag call

Closes gh-35358

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/DockerApi.java

@@ -65,6 +65,7 @@ import org.springframework.util.StringUtils;
  * @author Phillip Webb
  * @author Scott Frederick
  * @author Rafael Ceccone
+ * @author Moritz Halbritter
  * @since 2.3.0
  */
 public class DockerApi {
@@ -346,7 +347,15 @@ public class DockerApi {
 		public void tag(ImageReference sourceReference, ImageReference targetReference) throws IOException {
 			Assert.notNull(sourceReference, "SourceReference must not be null");
 			Assert.notNull(targetReference, "TargetReference must not be null");
-			URI uri = buildUrl("/images/" + sourceReference + "/tag", "repo", targetReference.toString());
+			String tag = targetReference.getTag();
+			URI uri;
+			if (tag == null) {
+				uri = buildUrl("/images/" + sourceReference + "/tag", "repo", targetReference.toString());
+			}
+			else {
+				uri = buildUrl("/images/" + sourceReference + "/tag", "repo",
+						targetReference.inTaglessForm().toString(), "tag", tag);
+			}
 			http().post(uri).close();
 		}
 

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/type/ImageReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@ import org.springframework.util.ObjectUtils;
  *
  * @author Phillip Webb
  * @author Scott Frederick
+ * @author Moritz Halbritter
  * @since 2.3.0
  * @see ImageName
  */
@@ -153,6 +154,17 @@ public final class ImageReference {
 		return new ImageReference(this.name, (this.tag != null) ? this.tag : LATEST, null);
 	}
 
+	/**
+	 * Return an {@link ImageReference} without the tag.
+	 * @return the image reference in tagless form
+	 */
+	public ImageReference inTaglessForm() {
+		if (this.tag == null) {
+			return this;
+		}
+		return new ImageReference(this.name, null, this.digest);
+	}
+
 	/**
 	 * Return an {@link ImageReference} containing either a tag or a digest. If neither
 	 * the digest nor the tag has been defined then tag {@code latest} is used.

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/docker/DockerApiTests.java

@@ -75,6 +75,7 @@ import static org.mockito.Mockito.times;
  * @author Phillip Webb
  * @author Scott Frederick
  * @author Rafael Ceccone
+ * @author Moritz Halbritter
  */
 @ExtendWith(MockitoExtension.class)
 class DockerApiTests {
@@ -419,7 +420,17 @@ class DockerApiTests {
 		void tagTagsImage() throws Exception {
 			ImageReference sourceReference = ImageReference.of("localhost:5000/ubuntu");
 			ImageReference targetReference = ImageReference.of("localhost:5000/ubuntu:tagged");
-			URI tagURI = new URI(IMAGES_URL + "/localhost:5000/ubuntu/tag?repo=localhost%3A5000%2Fubuntu%3Atagged");
+			URI tagURI = new URI(IMAGES_URL + "/localhost:5000/ubuntu/tag?repo=localhost%3A5000%2Fubuntu&tag=tagged");
+			given(http().post(tagURI)).willReturn(emptyResponse());
+			this.api.tag(sourceReference, targetReference);
+			then(http()).should().post(tagURI);
+		}
+
+		@Test
+		void tagRenamesImage() throws Exception {
+			ImageReference sourceReference = ImageReference.of("localhost:5000/ubuntu");
+			ImageReference targetReference = ImageReference.of("localhost:5000/ubuntu-2");
+			URI tagURI = new URI(IMAGES_URL + "/localhost:5000/ubuntu/tag?repo=localhost%3A5000%2Fubuntu-2");
 			given(http().post(tagURI)).willReturn(emptyResponse());
 			this.api.tag(sourceReference, targetReference);
 			then(http()).should().post(tagURI);

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/docker/type/ImageReferenceTests.java

@@ -29,6 +29,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  *
  * @author Phillip Webb
  * @author Scott Frederick
+ * @author Moritz Halbritter
  */
 class ImageReferenceTests {
 
@@ -272,4 +273,29 @@ class ImageReferenceTests {
 		assertThat(r1).isEqualTo(r1).isEqualTo(r2).isNotEqualTo(r3);
 	}
 
+	@Test
+	void withDigest() {
+		ImageReference reference = ImageReference.of("docker.io/library/ubuntu:bionic");
+		ImageReference updated = reference
+			.withDigest("sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d");
+		assertThat(updated).hasToString(
+				"docker.io/library/ubuntu@sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d");
+	}
+
+	@Test
+	void inTaglessFormWithDigest() {
+		ImageReference reference = ImageReference
+			.of("docker.io/library/ubuntu@sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d");
+		ImageReference updated = reference.inTaglessForm();
+		assertThat(updated).hasToString(
+				"docker.io/library/ubuntu@sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d");
+	}
+
+	@Test
+	void inTaglessForm() {
+		ImageReference reference = ImageReference.of("docker.io/library/ubuntu:bionic");
+		ImageReference updated = reference.inTaglessForm();
+		assertThat(updated).hasToString("docker.io/library/ubuntu");
+	}
+
 }