Add CompositeHealthIndicator

Add CompositeHealthIndicator that allows multiple HealthIndicators
to be combined into a single result.

Fixes gh-782

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

@@ -0,0 +1,61 @@
+/*
+ * 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.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * {@link HealthIndicator} that returns health indications from all registered delegates.
+ * 
+ * @author Tyler J. Frederick
+ * @author Phillip Webb
+ */
+public class CompositeHealthIndicator implements HealthIndicator<Map<String, Object>> {
+
+	private final Map<String, HealthIndicator<?>> indicators;
+
+	/**
+	 * Create a new {@link CompositeHealthIndicator}.
+	 */
+	public CompositeHealthIndicator() {
+		this.indicators = new LinkedHashMap<String, HealthIndicator<?>>();
+	}
+
+	/**
+	 * Create a new {@link CompositeHealthIndicator} from the specified indicators.
+	 * @param indicators a map of {@link HealthIndicator}s with the key being used as an
+	 * indicator name.
+	 */
+	public CompositeHealthIndicator(Map<String, HealthIndicator<?>> indicators) {
+		this.indicators = new LinkedHashMap<String, HealthIndicator<?>>(indicators);
+	}
+
+	public void addHealthIndicator(String name, HealthIndicator<?> indicator) {
+		this.indicators.put(name, indicator);
+	}
+
+	@Override
+	public Map<String, Object> health() {
+		Map<String, Object> health = new LinkedHashMap<String, Object>();
+		for (Map.Entry<String, HealthIndicator<?>> entry : this.indicators.entrySet()) {
+			health.put(entry.getKey(), entry.getValue().health());
+		}
+		return health;
+	}
+
+}

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

@@ -0,0 +1,94 @@
+/*
+ * 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.util.HashMap;
+import java.util.Map;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasEntry;
+import static org.junit.Assert.assertThat;
+import static org.mockito.BDDMockito.given;
+
+/**
+ * Tests for {@link CompositeHealthIndicator}
+ * 
+ * @author Tyler J. Frederick
+ * @author Phillip Webb
+ */
+public class CompositeHealthIndicatorTests {
+
+	@Mock
+	private HealthIndicator<String> one;
+
+	@Mock
+	private HealthIndicator<String> two;
+
+	@Mock
+	private HealthIndicator<String> three;
+
+	@Before
+	public void setup() {
+		MockitoAnnotations.initMocks(this);
+		given(this.one.health()).willReturn("1");
+		given(this.two.health()).willReturn("2");
+		given(this.three.health()).willReturn("3");
+	}
+
+	@Test
+	public void createWithIndicators() throws Exception {
+		Map<String, HealthIndicator<?>> indicators = new HashMap<String, HealthIndicator<?>>();
+		indicators.put("one", this.one);
+		indicators.put("two", this.two);
+		CompositeHealthIndicator composite = new CompositeHealthIndicator(indicators);
+		Map<String, Object> result = composite.health();
+		assertThat(result.size(), equalTo(2));
+		assertThat(result, hasEntry("one", (Object) "1"));
+		assertThat(result, hasEntry("two", (Object) "2"));
+	}
+
+	@Test
+	public void createWithIndicatorsAndAdd() throws Exception {
+		Map<String, HealthIndicator<?>> indicators = new HashMap<String, HealthIndicator<?>>();
+		indicators.put("one", this.one);
+		indicators.put("two", this.two);
+		CompositeHealthIndicator composite = new CompositeHealthIndicator(indicators);
+		composite.addHealthIndicator("three", this.three);
+		Map<String, Object> result = composite.health();
+		assertThat(result.size(), equalTo(3));
+		assertThat(result, hasEntry("one", (Object) "1"));
+		assertThat(result, hasEntry("two", (Object) "2"));
+		assertThat(result, hasEntry("three", (Object) "3"));
+	}
+
+	@Test
+	public void createWithoutAndAdd() throws Exception {
+		CompositeHealthIndicator composite = new CompositeHealthIndicator();
+		composite.addHealthIndicator("one", this.one);
+		composite.addHealthIndicator("two", this.two);
+		Map<String, Object> result = composite.health();
+		assertThat(result.size(), equalTo(2));
+		assertThat(result, hasEntry("one", (Object) "1"));
+		assertThat(result, hasEntry("two", (Object) "2"));
+	}
+
+}