Introduce HealthIndicatorRegistry

This commit introduces HealthIndicatorRegistry which handles registration of HealthIndicator instances. Registering new HealthIndicator instances is now possible in runtime.

Author: vpavic

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

@@ -20,7 +20,6 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
 
 import liquibase.integration.spring.SpringLiquibase;
 import org.flywaydb.core.Flyway;
@@ -42,8 +41,9 @@
 import org.springframework.boot.actuate.endpoint.RequestMappingEndpoint;
 import org.springframework.boot.actuate.endpoint.ShutdownEndpoint;
 import org.springframework.boot.actuate.endpoint.TraceEndpoint;
+import org.springframework.boot.actuate.health.DefaultHealthIndicatorRegistry;
 import org.springframework.boot.actuate.health.HealthAggregator;
-import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.actuate.health.HealthIndicatorRegistry;
 import org.springframework.boot.actuate.health.OrderedHealthAggregator;
 import org.springframework.boot.actuate.info.InfoContributor;
 import org.springframework.boot.actuate.trace.InMemoryTraceRepository;
@@ -75,7 +75,7 @@
  * @author Stephane Nicoll
  * @author Eddú Meléndez
  * @author Meang Akira Tanaka
- *
+ * @author Vedran Pavic
  */
 @Configuration
 @AutoConfigureAfter({ FlywayAutoConfiguration.class, LiquibaseAutoConfiguration.class })
@@ -84,7 +84,7 @@ public class EndpointAutoConfiguration {
 
 	private final HealthAggregator healthAggregator;
 
-	private final Map<String, HealthIndicator> healthIndicators;
+	private final HealthIndicatorRegistry healthIndicatorRegistry;
 
 	private final List<InfoContributor> infoContributors;
 
@@ -94,12 +94,12 @@ public class EndpointAutoConfiguration {
 
 	public EndpointAutoConfiguration(
 			ObjectProvider<HealthAggregator> healthAggregatorProvider,
-			ObjectProvider<Map<String, HealthIndicator>> healthIndicatorsProvider,
+			ObjectProvider<HealthIndicatorRegistry> healthIndicatorRegistryProvider,
 			ObjectProvider<List<InfoContributor>> infoContributorsProvider,
 			ObjectProvider<Collection<PublicMetrics>> publicMetricsProvider,
 			ObjectProvider<TraceRepository> traceRepositoryProvider) {
 		this.healthAggregator = healthAggregatorProvider.getIfAvailable();
-		this.healthIndicators = healthIndicatorsProvider.getIfAvailable();
+		this.healthIndicatorRegistry = healthIndicatorRegistryProvider.getIfAvailable();
 		this.infoContributors = infoContributorsProvider.getIfAvailable();
 		this.publicMetrics = publicMetricsProvider.getIfAvailable();
 		this.traceRepository = traceRepositoryProvider.getIfAvailable();
@@ -117,9 +117,9 @@ public HealthEndpoint healthEndpoint() {
 		return new HealthEndpoint(
 				this.healthAggregator == null ? new OrderedHealthAggregator()
 						: this.healthAggregator,
-				this.healthIndicators == null
-						? Collections.<String, HealthIndicator>emptyMap()
-						: this.healthIndicators);
+				this.healthIndicatorRegistry == null
+						? new DefaultHealthIndicatorRegistry()
+						: this.healthIndicatorRegistry);
 	}
 
 	@Bean

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

@@ -33,10 +33,12 @@
 import org.springframework.boot.actuate.health.CassandraHealthIndicator;
 import org.springframework.boot.actuate.health.CouchbaseHealthIndicator;
 import org.springframework.boot.actuate.health.DataSourceHealthIndicator;
+import org.springframework.boot.actuate.health.DefaultHealthIndicatorRegistry;
 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.HealthIndicatorRegistry;
 import org.springframework.boot.actuate.health.JmsHealthIndicator;
 import org.springframework.boot.actuate.health.MailHealthIndicator;
 import org.springframework.boot.actuate.health.MongoHealthIndicator;
@@ -86,6 +88,7 @@
  * @author Phillip Webb
  * @author Tommy Ludwig
  * @author Eddú Meléndez
+ * @author Vedran Pavic
  * @since 1.1.0
  */
 @Configuration
@@ -118,6 +121,19 @@ public OrderedHealthAggregator healthAggregator() {
 		return healthAggregator;
 	}
 
+	@Bean
+	@ConditionalOnMissingBean(HealthIndicatorRegistry.class)
+	public HealthIndicatorRegistry healthIndicatorRegistry(
+			Map<String, HealthIndicator> healthIndicators) {
+		HealthIndicatorRegistry registry = new DefaultHealthIndicatorRegistry();
+		for (Map.Entry<String, HealthIndicator> entry : healthIndicators.entrySet()) {
+			String name = entry.getKey();
+			int index = name.toLowerCase().indexOf("healthindicator");
+			registry.register(index > 0 ? name.substring(0, index) : name, entry.getValue());
+		}
+		return registry;
+	}
+
 	@Bean
 	@ConditionalOnMissingBean(HealthIndicator.class)
 	public ApplicationHealthIndicator applicationHealthIndicator() {

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/HealthEndpoint.java

@@ -16,12 +16,11 @@
 
 package org.springframework.boot.actuate.endpoint;
 
-import java.util.Map;
-
 import org.springframework.boot.actuate.health.CompositeHealthIndicator;
 import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.actuate.health.HealthIndicatorRegistry;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.util.Assert;
 
@@ -31,11 +30,14 @@
  * @author Dave Syer
  * @author Christian Dupuis
  * @author Andy Wilkinson
+ * @author Vedran Pavic
  */
 @ConfigurationProperties(prefix = "endpoints.health")
 public class HealthEndpoint extends AbstractEndpoint<Health> {
 
-	private final HealthIndicator healthIndicator;
+	private final HealthAggregator healthAggregator;
+
+	private final HealthIndicatorRegistry healthIndicatorRegistry;
 
 	/**
 	 * Time to live for cached result, in milliseconds.
@@ -45,19 +47,16 @@ public class HealthEndpoint extends AbstractEndpoint<Health> {
 	/**
 	 * Create a new {@link HealthIndicator} instance.
 	 * @param healthAggregator the health aggregator
-	 * @param healthIndicators the health indicators
+	 * @param healthIndicatorRegistry the health indicator registry
 	 */
 	public HealthEndpoint(HealthAggregator healthAggregator,
-			Map<String, HealthIndicator> healthIndicators) {
+			HealthIndicatorRegistry healthIndicatorRegistry) {
 		super("health", false);
 		Assert.notNull(healthAggregator, "HealthAggregator must not be null");
-		Assert.notNull(healthIndicators, "HealthIndicators must not be null");
-		CompositeHealthIndicator healthIndicator = new CompositeHealthIndicator(
-				healthAggregator);
-		for (Map.Entry<String, HealthIndicator> entry : healthIndicators.entrySet()) {
-			healthIndicator.addHealthIndicator(getKey(entry.getKey()), entry.getValue());
-		}
-		this.healthIndicator = healthIndicator;
+		Assert.notNull(healthIndicatorRegistry,
+				"healthIndicatorRegistry must not be null");
+		this.healthAggregator = healthAggregator;
+		this.healthIndicatorRegistry = healthIndicatorRegistry;
 	}
 
 	/**
@@ -78,19 +77,9 @@ public void setTimeToLive(long ttl) {
 	 */
 	@Override
 	public Health invoke() {
-		return this.healthIndicator.health();
+		HealthIndicator indicator = new CompositeHealthIndicator(
+				this.healthAggregator, this.healthIndicatorRegistry.getAll());
+		return indicator.health();
 	}
 
-	/**
-	 * Turns the bean name into a key that can be used in the map of health information.
-	 * @param name the bean name
-	 * @return the key
-	 */
-	private String getKey(String name) {
-		int index = name.toLowerCase().indexOf("healthindicator");
-		if (index > 0) {
-			return name.substring(0, index);
-		}
-		return name;
-	}
 }

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

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2016 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.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.util.Assert;
+
+/**
+ * Default implementation of {@link HealthIndicatorRegistry}.
+ *
+ * @author Vedran Pavic
+ */
+public class DefaultHealthIndicatorRegistry implements HealthIndicatorRegistry {
+
+	private final Map<String, HealthIndicator> healthIndicators =
+			new HashMap<String, HealthIndicator>();
+
+	@Override
+	public void register(String name, HealthIndicator healthIndicator) {
+		Assert.notNull(healthIndicator, "HealthIndicator must not be null");
+		synchronized (this.healthIndicators) {
+			if (this.healthIndicators.get(name) != null) {
+				throw new IllegalStateException(
+						"HealthIndicator with name '" + name + "' already registered");
+			}
+			this.healthIndicators.put(name, healthIndicator);
+		}
+	}
+
+	@Override
+	public HealthIndicator unregister(String name) {
+		synchronized (this.healthIndicators) {
+			return this.healthIndicators.remove(name);
+		}
+	}
+
+	@Override
+	public HealthIndicator get(String name) {
+		synchronized (this.healthIndicators) {
+			return this.healthIndicators.get(name);
+		}
+	}
+
+	@Override
+	public Map<String, HealthIndicator> getAll() {
+		synchronized (this.healthIndicators) {
+			return Collections.unmodifiableMap(
+					new HashMap<String, HealthIndicator>(this.healthIndicators));
+		}
+	}
+
+}

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

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2012-2016 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.util.Map;
+
+/**
+ * A registry of {@link HealthIndicator}s.
+ * <p>
+ * Implementations <strong>must</strong> be thread-safe.
+ *
+ * @author Andy Wilkinson
+ * @author Vedran Pavic
+ */
+public interface HealthIndicatorRegistry {
+
+	/**
+	 * Registers the given {@code healthIndicator}, associating it with the given
+	 * {@code name}.
+	 * @param name the name of the indicator
+	 * @param healthIndicator the indicator
+	 * @throws IllegalStateException if an indicator with the given {@code name} is
+	 * already registered.
+	 */
+	void register(String name, HealthIndicator healthIndicator);
+
+	/**
+	 * Unregisters the {@code HealthIndicator} previously registered with the given
+	 * {@code name}.
+	 * @param name the name of the indicator
+	 * @return the unregistered indicator, or {@code null} if no indicator was found in
+	 * the registry for the given {@code name}.
+	 */
+	HealthIndicator unregister(String name);
+
+	/**
+	 * Returns the health indicator registered with the given {@code name}.
+	 * @param name the name of the indicator
+	 * @return the health indicator, or {@code null} if no indicator was registered with
+	 * the given {@code name}.
+	 */
+	HealthIndicator get(String name);
+
+	/**
+	 * Returns a snapshot of the registered health indicators and their names. The
+	 * contents of the map do not reflect subsequent changes to the registry.
+	 * @return the snapshot of registered health indicators
+	 */
+	Map<String, HealthIndicator> getAll();
+
+}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/autoconfigure/HealthMvcEndpointAutoConfigurationTests.java

@@ -21,8 +21,10 @@
 
 import org.springframework.boot.actuate.endpoint.mvc.HealthMvcEndpoint;
 import org.springframework.boot.actuate.health.AbstractHealthIndicator;
+import org.springframework.boot.actuate.health.DefaultHealthIndicatorRegistry;
 import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.Health.Builder;
+import org.springframework.boot.actuate.health.HealthIndicatorRegistry;
 import org.springframework.boot.actuate.health.Status;
 import org.springframework.boot.autoconfigure.ImportAutoConfiguration;
 import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
@@ -42,6 +44,7 @@
  *
  * @author Dave Syer
  * @author Andy Wilkinson
+ * @author Vedran Pavic
  */
 public class HealthMvcEndpointAutoConfigurationTests {
 
@@ -94,6 +97,13 @@ public TestHealthIndicator testHealthIndicator() {
 			return new TestHealthIndicator();
 		}
 
+		@Bean
+		public HealthIndicatorRegistry healthIndicatorRegistry() {
+			DefaultHealthIndicatorRegistry registry = new DefaultHealthIndicatorRegistry();
+			registry.register("test", testHealthIndicator());
+			return registry;
+		}
+
 	}
 
 	static class TestHealthIndicator extends AbstractHealthIndicator {