Return thread dump in a JSON document

That is more consistent, and plays nicer with other services consuming
it.

graylog2-server/src/main/java/org/graylog2/rest/models/system/responses/SystemThreadDumpResponse.java

@@ -0,0 +1,35 @@
+/**
+ * This file is part of Graylog.
+ *
+ * Graylog is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Graylog is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Graylog.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.graylog2.rest.models.system.responses;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.auto.value.AutoValue;
+
+@AutoValue
+@JsonAutoDetect
+public abstract class SystemThreadDumpResponse {
+    @JsonProperty("threaddump")
+    public abstract String threadDump();
+
+    @JsonCreator
+    public static SystemThreadDumpResponse create(@JsonProperty("threaddump") String threadDump) {
+        return new AutoValue_SystemThreadDumpResponse(threadDump);
+    }
+}

graylog2-server/src/main/java/org/graylog2/shared/rest/resources/system/SystemResource.java

@@ -30,6 +30,7 @@
 import org.graylog2.plugin.cluster.ClusterId;
 import org.graylog2.rest.models.system.responses.SystemJVMResponse;
 import org.graylog2.rest.models.system.responses.SystemOverviewResponse;
+import org.graylog2.rest.models.system.responses.SystemThreadDumpResponse;
 import org.graylog2.shared.ServerVersion;
 import org.graylog2.shared.rest.resources.RestResource;
 import org.graylog2.shared.security.RestPermissions;
@@ -38,18 +39,17 @@
 import javax.ws.rs.GET;
 import javax.ws.rs.Path;
 import javax.ws.rs.Produces;
+import javax.ws.rs.core.MediaType;
 import java.io.ByteArrayOutputStream;
 import java.lang.management.ManagementFactory;
 import java.nio.charset.StandardCharsets;
 import java.util.Locale;
 import java.util.Map;
 
-import static javax.ws.rs.core.MediaType.APPLICATION_JSON;
-import static javax.ws.rs.core.MediaType.TEXT_PLAIN;
-
 @RequiresAuthentication
 @Api(value = "System", description = "System information of this node.")
 @Path("/system")
+@Produces(MediaType.APPLICATION_JSON)
 public class SystemResource extends RestResource {
     private final ServerStatus serverStatus;
     private final ClusterId clusterId;
@@ -63,7 +63,6 @@ public SystemResource(ServerStatus serverStatus, ClusterConfigService clusterCon
     @GET
     @Timed
     @ApiOperation(value = "Get system overview")
-    @Produces(APPLICATION_JSON)
     public SystemOverviewResponse system() {
         checkPermission(RestPermissions.SYSTEM_READ, serverStatus.getNodeId().toString());
 
@@ -86,7 +85,6 @@ public SystemOverviewResponse system() {
     @ApiOperation(value = "Get JVM information")
     @Path("/jvm")
     @Timed
-    @Produces(APPLICATION_JSON)
     public SystemJVMResponse jvm() {
         checkPermission(RestPermissions.JVMSTATS_READ, serverStatus.getNodeId().toString());
 
@@ -105,16 +103,15 @@ public SystemJVMResponse jvm() {
     @Timed
     @ApiOperation(value = "Get a thread dump")
     @Path("/threaddump")
-    @Produces(TEXT_PLAIN)
-    public String threaddump() {
+    public SystemThreadDumpResponse threaddump() {
         checkPermission(RestPermissions.THREADS_DUMP, serverStatus.getNodeId().toString());
 
         // The ThreadDump is built by internal codahale.metrics servlet library we are abusing.
         final ThreadDump threadDump = new ThreadDump(ManagementFactory.getThreadMXBean());
         final ByteArrayOutputStream output = new ByteArrayOutputStream();
 
         threadDump.dump(output);
-        return new String(output.toByteArray(), StandardCharsets.UTF_8);
+        return SystemThreadDumpResponse.create(new String(output.toByteArray(), StandardCharsets.UTF_8));
     }
 
     private Map<String, Long> bytesToValueMap(long bytes) {