Polish disk space health indicator

- Supply auto-configuration for the new indicator
 - As suggested in the pull request, include the free disk space and
   configured threshold in the health details
 - Update the documentation to describe the indicator and its
   two configuration settings
 - Use @ConfigurationProperties to bind the indicator's configuration.
   This should make the changes sympathetic to the work being done
   to automate the configuration properties documentation

Closes gh-1297

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/HealthIndicatorAutoConfiguration.java

@@ -30,6 +30,8 @@ import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.actuate.health.ApplicationHealthIndicator;
 import org.springframework.boot.actuate.health.CompositeHealthIndicator;
 import org.springframework.boot.actuate.health.DataSourceHealthIndicator;
+import org.springframework.boot.actuate.health.DiskSpaceHealthIndicator;
+import org.springframework.boot.actuate.health.DiskSpaceHealthIndicatorProperties;
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthIndicator;
 import org.springframework.boot.actuate.health.MongoHealthIndicator;
@@ -52,6 +54,7 @@ import org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration;
 import org.springframework.boot.autoconfigure.mongo.MongoDataAutoConfiguration;
 import org.springframework.boot.autoconfigure.redis.RedisAutoConfiguration;
 import org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration;
+import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.data.mongodb.core.MongoTemplate;
@@ -256,4 +259,22 @@ public class HealthIndicatorAutoConfiguration {
 		}
 	}
 
+	@Configuration
+	@ConditionalOnExpression("${health.diskspace.enabled:true}")
+	public static class DiskSpaceHealthIndicatorConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(name = "diskSpaceHealthIndicator")
+		public HealthIndicator diskSpaceHealthIndicator(
+				DiskSpaceHealthIndicatorProperties properties) {
+			return new DiskSpaceHealthIndicator(properties);
+		}
+
+		@Bean
+		@ConfigurationProperties("health.diskspace")
+		public DiskSpaceHealthIndicatorProperties diskSpaceHealthIndicatorProperties() {
+			return new DiskSpaceHealthIndicatorProperties();
+		}
+	}
+
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/DiskSpaceHealthIndicator.java

@@ -16,67 +16,45 @@
 
 package org.springframework.boot.actuate.health;
 
-import java.io.File;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.beans.factory.annotation.Value;
-import org.springframework.stereotype.Component;
-import org.springframework.util.Assert;
 
 /**
- * A {@link HealthIndicator} that checks for available disk space.
+ * A {@link HealthIndicator} that checks available disk space and reports a status of
+ * {@link Status#DOWN} when it drops below a configurable threshold.
  *
  * @author Mattias Severson
+ * @author Andy Wilkinson
  * @since 1.2.0
  */
-@Component
 public class DiskSpaceHealthIndicator extends AbstractHealthIndicator {
+
 	private static Log logger = LogFactory.getLog(DiskSpaceHealthIndicator.class);
 
-	private final File path;
-	private final long thresholdBytes;
+	private final DiskSpaceHealthIndicatorProperties properties;
 
 	/**
-	 * Constructor.
-	 * @param path The path to a directory for checking available disk space. The
-	 *                application must have read access to this path. Additionally, the
-	 *                {@link java.lang.SecurityManager#checkRead(String)} will be called
-	 *                if a security manager is used.
-	 *                By default, it uses the system property {@code user.dir}, i.e. the
-	 *                current directory when the JVM was started.
-	 * @param thresholdBytes The threshold (in Bytes) of remaining disk space that will
-	 *                          trigger this health indicator when exceeded.
-	 *                          Default value is 10485760 Bytes (10 MB).
+	 * Create a new {@code DiskSpaceHealthIndicator}
 	 */
 	@Autowired
-	public DiskSpaceHealthIndicator(@Value("${health.path?:${user.dir}}") String path,
-									@Value("${health.threshold.bytes:10485760}") long thresholdBytes) {
-		this.path = new File(path);
-		this.thresholdBytes = thresholdBytes;
-		verifyPathIsAccessible(this.path);
-		Assert.isTrue(thresholdBytes >= 0, "thresholdBytes must be greater than 0");
+	public DiskSpaceHealthIndicator(DiskSpaceHealthIndicatorProperties properties) {
+		this.properties = properties;
 	}
 
 	@Override
 	protected void doHealthCheck(Health.Builder builder) throws Exception {
-		long diskFreeInBytes = this.path.getFreeSpace();
-		if (diskFreeInBytes >= this.thresholdBytes) {
+		long diskFreeInBytes = this.properties.getPath().getFreeSpace();
+		if (diskFreeInBytes >= this.properties.getThreshold()) {
 			builder.up();
-		} else {
-			logger.warn(String.format("Free disk space threshold exceeded. " +
-							"Available: %d bytes (threshold: %d bytes).",
-					diskFreeInBytes, this.thresholdBytes));
-			builder.down();
-		}
-	}
-
-	private static void verifyPathIsAccessible(File path) {
-		if (!path.exists()) {
-			throw new IllegalArgumentException(String.format("Path does not exist: %s", path));
 		}
-		if (!path.canRead()) {
-			throw new IllegalStateException(String.format("Path cannot be read: %s", path));
+		else {
+			logger.warn(String.format("Free disk space below threshold. "
+					+ "Available: %d bytes (threshold: %d bytes)", diskFreeInBytes,
+					this.properties.getThreshold()));
+			builder.down();
 		}
+		builder.withDetail("free", diskFreeInBytes).withDetail("threshold",
+				this.properties.getThreshold());
 	}
 }

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/DiskSpaceHealthIndicatorProperties.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2014 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.
+ * 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 org.springframework.boot.actuate.health;
+
+import java.io.File;
+
+import org.springframework.util.Assert;
+
+/**
+ * External configuration properties for {@link DiskSpaceHealthIndicator}
+ *
+ * @author Andy Wilkinson
+ * @since 1.2.0
+ */
+public class DiskSpaceHealthIndicatorProperties {
+
+	private File path = new File(".");
+
+	private long threshold = 10 * 1024 * 1024;
+
+	public File getPath() {
+		return this.path;
+	}
+
+	public void setPath(File path) {
+		if (!path.exists()) {
+			throw new IllegalArgumentException(String.format("Path '%s' does not exist",
+					path));
+		}
+		if (!path.canRead()) {
+			throw new IllegalStateException(String.format("Path '%s' cannot be read",
+					path));
+		}
+		this.path = path;
+	}
+
+	public long getThreshold() {
+
+		return this.threshold;
+	}
+
+	public void setThreshold(long threshold) {
+		Assert.isTrue(threshold >= 0, "threshold must be greater than 0");
+		this.threshold = threshold;
+	}
+}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/DiskSpaceHealthIndicatorTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.health;
 
 import java.io.File;
+
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
@@ -24,7 +25,6 @@ import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
-import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Mockito.when;
@@ -49,10 +49,10 @@ public class DiskSpaceHealthIndicatorTests {
 
 	@Before
 	public void setUp() throws Exception {
-		this.healthIndicator =
-				new DiskSpaceHealthIndicator(DiskSpaceHealthIndicatorTests.class.getResource("").getPath(),
-				THRESHOLD_BYTES);
-		ReflectionTestUtils.setField(this.healthIndicator, "path", this.fileMock);
+		when(this.fileMock.exists()).thenReturn(true);
+		when(this.fileMock.canRead()).thenReturn(true);
+		this.healthIndicator = new DiskSpaceHealthIndicator(createProperties(
+				this.fileMock, THRESHOLD_BYTES));
 	}
 
 	@Test
@@ -61,6 +61,8 @@ public class DiskSpaceHealthIndicatorTests {
 
 		Health health = this.healthIndicator.health();
 		assertEquals(Status.UP, health.getStatus());
+		assertEquals(THRESHOLD_BYTES, health.getDetails().get("threshold"));
+		assertEquals(THRESHOLD_BYTES + 10, health.getDetails().get("free"));
 	}
 
 	@Test
@@ -69,21 +71,14 @@ public class DiskSpaceHealthIndicatorTests {
 
 		Health health = this.healthIndicator.health();
 		assertEquals(Status.DOWN, health.getStatus());
+		assertEquals(THRESHOLD_BYTES, health.getDetails().get("threshold"));
+		assertEquals(THRESHOLD_BYTES - 10, health.getDetails().get("free"));
 	}
 
-	@Test
-	public void throwsExceptionForUnknownPath() {
-		exception.expect(IllegalArgumentException.class);
-		exception.expectMessage("Path does not exist: an_path_that_does_not_exist");
-
-		new DiskSpaceHealthIndicator("an_path_that_does_not_exist", THRESHOLD_BYTES);
-	}
-
-	@Test
-	public void throwsExceptionForNegativeThreshold() {
-		exception.expect(IllegalArgumentException.class);
-		exception.expectMessage("thresholdBytes must be greater than 0");
-
-		new DiskSpaceHealthIndicator(DiskSpaceHealthIndicatorTests.class.getResource("").getPath(), -1);
+	private DiskSpaceHealthIndicatorProperties createProperties(File path, long threshold) {
+		DiskSpaceHealthIndicatorProperties properties = new DiskSpaceHealthIndicatorProperties();
+		properties.setPath(path);
+		properties.setThreshold(threshold);
+		return properties;
 	}
 }

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -387,6 +387,10 @@ content into your application; rather pick only the properties that you need.
 	endpoints.trace.sensitive=true
 	endpoints.trace.enabled=true
 
+	# HEALTH INDICATORS
+	health.diskspace.path=.
+	health.diskspace.threshold=10485760
+
 	# MVC ONLY ENDPOINTS
 	endpoints.jolokia.path=jolokia
 	endpoints.jolokia.sensitive=true

spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -165,10 +165,10 @@ To provide custom health information you can register a Spring bean that impleme
 Spring Boot provides a
 {sc-spring-boot-actuator}/health/DataSourceHealthIndicator.{sc-ext}[`DataSourceHealthIndicator`]
 implementation that attempts a simple database test (reusing the validation query set on the data
-source, if any) as well as implementations for Redis, MongoDB and RabbitMQ.
-
-Spring Boot adds the `HealthIndicator` instances automatically if beans of type `DataSource`,
-`MongoTemplate`, `RedisConnectionFactory`, `RabbitTemplate` are present in the `ApplicationContext`.
+source, if any) as well as implementations for Redis, MongoDB and RabbitMQ. Spring Boot adds the
+`HealthIndicator` instances automatically if beans of type `DataSource`, `MongoTemplate`,
+`RedisConnectionFactory`, and `RabbitTemplate` respectively are present in the
+`ApplicationContext`. A health indicator that checks free disk space is also provided.
 
 Besides implementing custom a `HealthIndicator` type and using out-of-box {sc-spring-boot-actuator}/health/Status.{sc-ext}[`Status`]
 types, it is also possible to introduce custom `Status` types for different or more complex system