Add pullPolicy option for image building

This commit adds a pullPolicy option to the configuration of the Maven
plugin spring-boot:build-image goal and the Gradle plugin bootBuildImage
task. The new option gives users control over pulling the builder image
and run image from a remote image registry to the local Docker daemon.

See gh-22736

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImage.java

@@ -34,6 +34,7 @@ import org.gradle.api.tasks.options.Option;
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
 import org.springframework.boot.buildpack.platform.build.Builder;
 import org.springframework.boot.buildpack.platform.build.Creator;
+import org.springframework.boot.buildpack.platform.build.PullPolicy;
 import org.springframework.boot.buildpack.platform.docker.transport.DockerEngineException;
 import org.springframework.boot.buildpack.platform.docker.type.ImageName;
 import org.springframework.boot.buildpack.platform.docker.type.ImageReference;
@@ -69,6 +70,8 @@ public class BootBuildImage extends DefaultTask {
 
 	private boolean verboseLogging;
 
+	private PullPolicy pullPolicy;
+
 	public BootBuildImage() {
 		this.jar = getProject().getObjects().fileProperty();
 		this.targetJavaVersion = getProject().getObjects().property(JavaVersion.class);
@@ -224,6 +227,25 @@ public class BootBuildImage extends DefaultTask {
 		this.verboseLogging = verboseLogging;
 	}
 
+	/**
+	 * Returns image pull policy that will be used when building the image.
+	 * @return whether images should be pulled
+	 */
+	@Input
+	@Optional
+	public PullPolicy getPullPolicy() {
+		return this.pullPolicy;
+	}
+
+	/**
+	 * Sets image pull policy that will be used when building the image.
+	 * @param pullPolicy image pull policy {@link PullPolicy}
+	 */
+	@Option(option = "pullPolicy", description = "The image pull policy")
+	public void setPullPolicy(PullPolicy pullPolicy) {
+		this.pullPolicy = pullPolicy;
+	}
+
 	@TaskAction
 	void buildImage() throws DockerEngineException, IOException {
 		Builder builder = new Builder();
@@ -255,6 +277,7 @@ public class BootBuildImage extends DefaultTask {
 		request = customizeCreator(request);
 		request = request.withCleanCache(this.cleanCache);
 		request = request.withVerboseLogging(this.verboseLogging);
+		request = customizePullPolicy(request);
 		return request;
 	}
 
@@ -290,6 +313,13 @@ public class BootBuildImage extends DefaultTask {
 		return request;
 	}
 
+	private BuildRequest customizePullPolicy(BuildRequest request) {
+		if (this.pullPolicy != null) {
+			request = request.withPullPolicy(this.pullPolicy);
+		}
+		return request;
+	}
+
 	private String translateTargetJavaVersion() {
 		return this.targetJavaVersion.get().getMajorVersion() + ".*";
 	}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImageTests.java

@@ -27,6 +27,7 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
+import org.springframework.boot.buildpack.platform.build.PullPolicy;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -194,4 +195,15 @@ class BootBuildImageTests {
 		assertThat(this.buildImage.createRequest().getRunImage().getName()).isEqualTo("test/run");
 	}
 
+	@Test
+	void whenUsingDefaultConfigurationThenRequestHasNoPullDisabled() {
+		assertThat(this.buildImage.createRequest().getPullPolicy()).isEqualTo(PullPolicy.ALWAYS);
+	}
+
+	@Test
+	void whenNoPullIsEnabledThenRequestHasNoPullEnabled() {
+		this.buildImage.setPullPolicy(PullPolicy.NEVER);
+		assertThat(this.buildImage.createRequest().getPullPolicy()).isEqualTo(PullPolicy.NEVER);
+	}
+
 }