Ensure that, where appropriate, actuator endpoints always produce JSON

Previously, the Actuator’s endpoints did not specify a produces
attribute on their request mappings. With Jackson’s XML binding on the
classpath, this would lead to requests made by a browser receiving
application/xml responses (due to the Accept header indicating that
application/xml is preferred). This was problematic as some of the
response payloads were not legal xml. Problems included XML tags
beginning with ‘\’ or containing ‘#’.

This commit updates the endpoints to specify that they produce
application/json. The environment and metrics endpoints have also been
updated so that always return a JSON object, even when they are
returning a single entry. This consistency avoids problems where
clients may not consider a single scalar value to be legal JSON.

Closes gh-2449

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

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.endpoint.mvc;
 
 import org.springframework.boot.actuate.endpoint.Endpoint;
+import org.springframework.http.MediaType;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.ResponseBody;
@@ -38,7 +39,7 @@ public class EndpointMvcAdapter extends AbstractEndpointMvcAdapter<Endpoint<?>>
 	}
 
 	@Override
-	@RequestMapping(method = RequestMethod.GET)
+	@RequestMapping(method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
 	@ResponseBody
 	public Object invoke() {
 		return super.invoke();

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

@@ -24,6 +24,7 @@ import org.springframework.core.env.Environment;
 import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.PropertySources;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
@@ -46,7 +47,7 @@ public class EnvironmentMvcEndpoint extends EndpointMvcAdapter
 		super(delegate);
 	}
 
-	@RequestMapping(value = "/{name:.*}", method = RequestMethod.GET)
+	@RequestMapping(value = "/{name:.*}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
 	@ResponseBody
 	@HypermediaDisabled
 	public Object value(@PathVariable String name) {

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

@@ -28,6 +28,7 @@ import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.context.EnvironmentAware;
 import org.springframework.core.env.Environment;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.GrantedAuthority;
@@ -123,7 +124,7 @@ public class HealthMvcEndpoint extends AbstractEndpointMvcAdapter<HealthEndpoint
 		this.statusMapping.put(statusCode, httpStatus);
 	}
 
-	@RequestMapping
+	@RequestMapping(produces = MediaType.APPLICATION_JSON_VALUE)
 	@ResponseBody
 	public Object invoke(Principal principal) {
 		if (!getDelegate().isEnabled()) {

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

@@ -20,6 +20,7 @@ import java.util.Map;
 
 import org.springframework.boot.actuate.endpoint.MetricsEndpoint;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
@@ -42,7 +43,7 @@ public class MetricsMvcEndpoint extends EndpointMvcAdapter {
 		this.delegate = delegate;
 	}
 
-	@RequestMapping(value = "/{name:.*}", method = RequestMethod.GET)
+	@RequestMapping(value = "/{name:.*}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
 	@ResponseBody
 	@HypermediaDisabled
 	public Object value(@PathVariable String name) {

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.endpoint.mvc;
 
+import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.regex.Pattern;
@@ -29,6 +30,7 @@ import java.util.regex.Pattern;
  * @param <T> The source data type
  * @author Phillip Webb
  * @author Sergei Egorov
+ * @author Andy Wilkinson
  * @since 1.3.0
  */
 abstract class NamePatternFilter<T> {
@@ -41,9 +43,12 @@ abstract class NamePatternFilter<T> {
 		this.source = source;
 	}
 
-	public Object getResults(String name) {
+	public Map<String, Object> getResults(String name) {
 		if (!isRegex(name)) {
-			return getValue(this.source, name);
+			Object value = getValue(this.source, name);
+			Map<String, Object> result = new HashMap<String, Object>();
+			result.put(name, value);
+			return result;
 		}
 		Pattern pattern = Pattern.compile(name);
 		ResultCollectingNameCallback resultCollector = new ResultCollectingNameCallback(

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/EnvironmentMvcEndpointTests.java

@@ -41,7 +41,6 @@ import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 import org.springframework.web.context.WebApplicationContext;
 
 import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.equalToIgnoringCase;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
@@ -79,7 +78,7 @@ public class EnvironmentMvcEndpointTests {
 	@Test
 	public void sub() throws Exception {
 		this.mvc.perform(get("/env/foo")).andExpect(status().isOk())
-				.andExpect(content().string(equalToIgnoringCase("bar")));
+				.andExpect(content().string("{\"foo\":\"bar\"}"));
 	}
 
 	@Test

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/MetricsMvcEndpointTests.java

@@ -87,7 +87,7 @@ public class MetricsMvcEndpointTests {
 	@Test
 	public void specificMetric() throws Exception {
 		this.mvc.perform(get("/metrics/foo")).andExpect(status().isOk())
-				.andExpect(content().string(equalTo("1")));
+				.andExpect(content().string(equalTo("{\"foo\":1}")));
 	}
 
 	@Test

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/NamePatternFilterTests.java

@@ -21,27 +21,29 @@ import java.util.Map;
 import org.junit.Test;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasEntry;
 import static org.junit.Assert.assertThat;
 
 /**
  * Tests for {@link NamePatternFilter}.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  */
 public class NamePatternFilterTests {
 
 	@Test
 	public void nonRegex() throws Exception {
 		MockNamePatternFilter filter = new MockNamePatternFilter();
-		assertThat(filter.getResults("not.a.regex"), equalTo((Object) "not.a.regex"));
+		assertThat(filter.getResults("not.a.regex"),
+				hasEntry("not.a.regex", (Object) "not.a.regex"));
 		assertThat(filter.isGetNamesCalled(), equalTo(false));
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	public void regex() throws Exception {
 		MockNamePatternFilter filter = new MockNamePatternFilter();
-		Map<String, Object> results = (Map<String, Object>) filter.getResults("fo.*");
+		Map<String, Object> results = filter.getResults("fo.*");
 		assertThat(results.get("foo"), equalTo((Object) "foo"));
 		assertThat(results.get("fool"), equalTo((Object) "fool"));
 		assertThat(filter.isGetNamesCalled(), equalTo(true));