Consider time in BuildInfo up-to-date checks and allow it to be set

Closes gh-12111
Closes gh-12266

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/integrating-with-actuator.adoc

@@ -38,6 +38,9 @@ By default, the generated build information is derived from the project:
 | `build.version`
 | The version of the project
 
+| `build.time`
+| The time at which the project is being built
+
 |===
 
 The properties can be customized using the DSL:
@@ -47,6 +50,13 @@ The properties can be customized using the DSL:
 include::../gradle/integrating-with-actuator/build-info-custom-values.gradle[tags=custom-values]
 ----
 
+The default value for `build.time` is the instant at which the project is being built. A
+side-effect of this is that the task will never be up-to-date and, therefore, builds will
+take slighly longer as more tasks will have to be executed. Another side-effect is that
+the task's output will always change and, therefore, the build will not be truly
+repeatable. If you value build performance or repeatability more highly than the accuracy
+of the `build.time` property, set `time` to `null` or a fixed value.
+
 Additional properties can also be added to the build information:
 
 [source,groovy,indent=0,subs="verbatim"]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfo.java

@@ -61,7 +61,8 @@ public class BuildInfo extends ConventionTask {
 											? "unspecified"
 											: this.properties.getArtifact(),
 									this.properties.getVersion(),
-									this.properties.getName(), coerceToStringValues(
+									this.properties.getName(), this.properties.getTime(),
+									coerceToStringValues(
 											this.properties.getAdditional())));
 		}
 		catch (IOException ex) {

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoProperties.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.gradle.tasks.buildinfo;
 
 import java.io.Serializable;
+import java.time.Instant;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -40,10 +41,13 @@ public class BuildInfoProperties implements Serializable {
 
 	private String name;
 
+	private Instant time;
+
 	private Map<String, Object> additionalProperties = new HashMap<>();
 
 	BuildInfoProperties(Project project) {
 		this.project = project;
+		this.time = Instant.now();
 	}
 
 	/**
@@ -121,6 +125,23 @@ public class BuildInfoProperties implements Serializable {
 		this.name = name;
 	}
 
+	/**
+	 * Returns the value used for the {@code build.time} property. Defaults to
+	 * {@link Instant#now} when the {@code BuildInfoProperties} instance was created.
+	 * @return the time
+	 */
+	public Instant getTime() {
+		return this.time;
+	}
+
+	/**
+	 * Sets the value used for the {@code build.time} property.
+	 * @param time the build time
+	 */
+	public void setTime(Instant time) {
+		this.time = time;
+	}
+
 	/**
 	 * Returns the additional properties that will be included. When written, the name of
 	 * each additional property is prefixed with {@code build.}.
@@ -152,6 +173,7 @@ public class BuildInfoProperties implements Serializable {
 		result = prime * result + ((this.group == null) ? 0 : this.group.hashCode());
 		result = prime * result + ((this.name == null) ? 0 : this.name.hashCode());
 		result = prime * result + ((this.version == null) ? 0 : this.version.hashCode());
+		result = prime * result + ((this.time == null) ? 0 : this.time.hashCode());
 		return result;
 	}
 
@@ -207,6 +229,14 @@ public class BuildInfoProperties implements Serializable {
 		else if (!this.version.equals(other.version)) {
 			return false;
 		}
+		if (this.time == null) {
+			if (other.time != null) {
+				return false;
+			}
+		}
+		else if (!this.time.equals(other.time)) {
+			return false;
+		}
 		return true;
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -69,48 +69,19 @@ public class BuildInfoIntegrationTests {
 	}
 
 	@Test
-	public void upToDateWhenExecutedTwice() {
+	public void notUpToDateWhenExecutedTwiceAsTimeChanges() {
 		assertThat(this.gradleBuild.build("buildInfo").task(":buildInfo").getOutcome())
 				.isEqualTo(TaskOutcome.SUCCESS);
 		assertThat(this.gradleBuild.build("buildInfo").task(":buildInfo").getOutcome())
-				.isEqualTo(TaskOutcome.UP_TO_DATE);
-	}
-
-	@Test
-	public void notUpToDateWhenDestinationDirChanges() {
-		notUpToDateWithChangeToProperty("buildInfoDestinationDir");
-	}
-
-	@Test
-	public void notUpToDateWhenProjectArtifactChanges() {
-		notUpToDateWithChangeToProperty("buildInfoArtifact");
-	}
-
-	@Test
-	public void notUpToDateWhenProjectGroupChanges() {
-		notUpToDateWithChangeToProperty("buildInfoGroup");
-	}
-
-	@Test
-	public void notUpToDateWhenProjectVersionChanges() {
-		notUpToDateWithChangeToProperty("buildInfoVersion");
-	}
-
-	@Test
-	public void notUpToDateWhenProjectNameChanges() {
-		notUpToDateWithChangeToProperty("buildInfoName");
+				.isEqualTo(TaskOutcome.SUCCESS);
 	}
 
 	@Test
-	public void notUpToDateWhenAdditionalPropertyChanges() {
-		notUpToDateWithChangeToProperty("buildInfoAdditional");
-	}
-
-	private void notUpToDateWithChangeToProperty(String name) {
-		assertThat(this.gradleBuild.build("buildInfo", "--stacktrace").task(":buildInfo")
+	public void upToDateWhenExecutedTwiceWithFixedTime() {
+		assertThat(this.gradleBuild.build("buildInfo", "-PnullTime").task(":buildInfo")
 				.getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
-		assertThat(this.gradleBuild.build("buildInfo", "-P" + name + "=changed")
-				.task(":buildInfo").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(this.gradleBuild.build("buildInfo", "-PnullTime").task(":buildInfo")
+				.getOutcome()).isEqualTo(TaskOutcome.UP_TO_DATE);
 	}
 
 	private Properties buildInfoProperties() {

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -19,6 +19,8 @@ package org.springframework.boot.gradle.tasks.buildinfo;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
+import java.time.Instant;
+import java.time.format.DateTimeFormatter;
 import java.util.Properties;
 
 import org.gradle.api.Project;
@@ -91,6 +93,29 @@ public class BuildInfoTests {
 		assertThat(buildInfoProperties(task)).containsEntry("build.version", "2.3.4");
 	}
 
+	@Test
+	public void timeIsSetInProperties() {
+		BuildInfo task = createTask(createProject("test"));
+		assertThat(buildInfoProperties(task)).containsEntry("build.time",
+				DateTimeFormatter.ISO_INSTANT.format(task.getProperties().getTime()));
+	}
+
+	@Test
+	public void timeCanBeRemovedFromProperties() {
+		BuildInfo task = createTask(createProject("test"));
+		task.getProperties().setTime(null);
+		assertThat(buildInfoProperties(task)).doesNotContainKey("build.time");
+	}
+
+	@Test
+	public void timeCanBeCustomizedInProperties() {
+		Instant now = Instant.now();
+		BuildInfo task = createTask(createProject("test"));
+		task.getProperties().setTime(now);
+		assertThat(buildInfoProperties(task)).containsEntry("build.time",
+				DateTimeFormatter.ISO_INSTANT.format(now));
+	}
+
 	@Test
 	public void additionalPropertiesAreReflectedInProperties() {
 		BuildInfo task = createTask(createProject("test"));

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoIntegrationTests.gradle

@@ -16,5 +16,8 @@ task buildInfo(type: org.springframework.boot.gradle.tasks.buildinfo.BuildInfo)
 		group = property('buildInfoGroup', 'foo')
 		name = property('buildInfoName', 'foo')
 		additional = ['additional': property('buildInfoAdditional', 'foo')]
+		if (project.hasProperty('nullTime')) {
+			time = null
+		}
 	}
 }

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/BuildPropertiesWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -19,8 +19,8 @@ package org.springframework.boot.loader.tools;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.text.SimpleDateFormat;
-import java.util.Date;
+import java.time.Instant;
+import java.time.format.DateTimeFormatter;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Properties;
@@ -74,7 +74,10 @@ public final class BuildPropertiesWriter {
 		properties.put("build.artifact", project.getArtifact());
 		properties.put("build.name", project.getName());
 		properties.put("build.version", project.getVersion());
-		properties.put("build.time", formatDate(new Date()));
+		if (project.getTime() != null) {
+			properties.put("build.time",
+					DateTimeFormatter.ISO_INSTANT.format(project.getTime()));
+		}
 		if (project.getAdditionalProperties() != null) {
 			for (Map.Entry<String, String> entry : project.getAdditionalProperties()
 					.entrySet()) {
@@ -84,11 +87,6 @@ public final class BuildPropertiesWriter {
 		return properties;
 	}
 
-	private String formatDate(Date date) {
-		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
-		return sdf.format(date);
-	}
-
 	/**
 	 * Build-system agnostic details of a project.
 	 */
@@ -102,14 +100,17 @@ public final class BuildPropertiesWriter {
 
 		private final String version;
 
+		private final Instant time;
+
 		private final Map<String, String> additionalProperties;
 
 		public ProjectDetails(String group, String artifact, String version, String name,
-				Map<String, String> additionalProperties) {
+				Instant time, Map<String, String> additionalProperties) {
 			this.group = group;
 			this.artifact = artifact;
 			this.name = name;
 			this.version = version;
+			this.time = time;
 			validateAdditionalProperties(additionalProperties);
 			this.additionalProperties = additionalProperties;
 		}
@@ -141,6 +142,10 @@ public final class BuildPropertiesWriter {
 			return this.version;
 		}
 
+		public Instant getTime() {
+			return this.time;
+		}
+
 		public Map<String, String> getAdditionalProperties() {
 			return this.additionalProperties;
 		}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/BuildInfoMojo.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.maven;
 
 import java.io.File;
+import java.time.Instant;
 import java.util.Map;
 
 import org.apache.maven.plugin.AbstractMojo;
@@ -71,7 +72,8 @@ public class BuildInfoMojo extends AbstractMojo {
 			new BuildPropertiesWriter(this.outputFile)
 					.writeBuildProperties(new ProjectDetails(this.project.getGroupId(),
 							this.project.getArtifactId(), this.project.getVersion(),
-							this.project.getName(), this.additionalProperties));
+							this.project.getName(), Instant.now(),
+							this.additionalProperties));
 			this.buildContext.refresh(this.outputFile);
 		}
 		catch (NullAdditionalPropertyValueException ex) {