List of existing plugins with Node Info API

We want to display information about loaded plugins in Node Info API using plugin option:

```sh
curl http://localhost:9200/_nodes?plugin=true
```

For example, on a 4 nodes cluster, it could provide the following output:

```javascript
{
  "ok" : true,
  "cluster_name" : "test-cluster-MacBook-Air-de-David.local",
  "nodes" : {
    "lodYfbFTRnmwE6rjWGGyQQ" : {
      "name" : "node1",
      "transport_address" : "inet[/172.18.58.139:9300]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9200]",
      "plugins" : [ ]
    },
    "hJLXmY_NTrCytiIMbX4_1g" : {
      "name" : "node4",
      "transport_address" : "inet[/172.18.58.139:9303]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9203]",
      "plugins" : [ {
        "name" : "test-plugin",
        "description" : "test-plugin description",
        "site" : true,
        "jvm" : false
      }, {
        "name" : "test-no-version-plugin",
        "description" : "test-no-version-plugin description",
        "site" : true,
        "jvm" : false
      }, {
        "name" : "dummy",
        "description" : "No description found for dummy.",
        "url" : "/_plugin/dummy/",
        "site" : false,
        "jvm" : true
      } ]
    },
    "bnoySsBfTrSzbDRZ0BFHvg" : {
      "name" : "node2",
      "transport_address" : "inet[/172.18.58.139:9301]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9201]",
      "plugins" : [ {
        "name" : "dummy",
        "description" : "This is a description for a dummy test site plugin.",
        "url" : "/_plugin/dummy/",
        "site" : false,
        "jvm" : true
      } ]
    },
    "0Vwil01LSfK9YgRrMce3Ug" : {
      "name" : "node3",
      "transport_address" : "inet[/172.18.58.139:9302]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9202]",
      "plugins" : [ {
        "name" : "test-plugin",
        "description" : "test-plugin description",
        "site" : true,
        "jvm" : false
      } ]
    }
  }
}
```

Information are cached for 10 seconds by default. Modify `plugins.info_refresh_interval` property if needed.
Setting `plugins.info_refresh_interval` to `-1` will cause infinite caching.
Setting `plugins.info_refresh_interval` to `0` will disable caching.

Closes #2668.

src/main/java/org/elasticsearch/action/admin/cluster/node/info/NodeInfo.java

@@ -76,12 +76,15 @@ public class NodeInfo extends NodeOperationResponse {
     @Nullable
     private HttpInfo http;
 
+    @Nullable
+    private PluginsInfo plugins;
+
     NodeInfo() {
     }
 
     public NodeInfo(@Nullable String hostname, Version version, DiscoveryNode node, @Nullable ImmutableMap<String, String> serviceAttributes, @Nullable Settings settings,
                     @Nullable OsInfo os, @Nullable ProcessInfo process, @Nullable JvmInfo jvm, @Nullable ThreadPoolInfo threadPool, @Nullable NetworkInfo network,
-                    @Nullable TransportInfo transport, @Nullable HttpInfo http) {
+                    @Nullable TransportInfo transport, @Nullable HttpInfo http, @Nullable PluginsInfo plugins) {
         super(node);
         this.hostname = hostname;
         this.version = version;
@@ -94,6 +97,7 @@ public class NodeInfo extends NodeOperationResponse {
         this.network = network;
         this.transport = transport;
         this.http = http;
+        this.plugins = plugins;
     }
 
     /**
@@ -174,6 +178,11 @@ public class NodeInfo extends NodeOperationResponse {
         return http;
     }
 
+    @Nullable
+    public PluginsInfo getPlugins() {
+        return this.plugins;
+    }
+
     public static NodeInfo readNodeInfo(StreamInput in) throws IOException {
         NodeInfo nodeInfo = new NodeInfo();
         nodeInfo.readFrom(in);
@@ -219,6 +228,9 @@ public class NodeInfo extends NodeOperationResponse {
         if (in.readBoolean()) {
             http = HttpInfo.readHttpInfo(in);
         }
+        if (in.readBoolean()) {
+            plugins = PluginsInfo.readPluginsInfo(in);
+        }
     }
 
     @Override
@@ -289,5 +301,12 @@ public class NodeInfo extends NodeOperationResponse {
             out.writeBoolean(true);
             http.writeTo(out);
         }
+        if (plugins == null) {
+            out.writeBoolean(false);
+        } else {
+            out.writeBoolean(true);
+            plugins.writeTo(out);
+        }
     }
+
 }

src/main/java/org/elasticsearch/action/admin/cluster/node/info/NodesInfoRequest.java

@@ -38,6 +38,7 @@ public class NodesInfoRequest extends NodesOperationRequest<NodesInfoRequest> {
     private boolean network = false;
     private boolean transport = false;
     private boolean http = false;
+    private boolean plugin = false;
 
     public NodesInfoRequest() {
     }
@@ -62,6 +63,7 @@ public class NodesInfoRequest extends NodesOperationRequest<NodesInfoRequest> {
         network = false;
         transport = false;
         http = false;
+        plugin = false;
         return this;
     }
 
@@ -77,6 +79,7 @@ public class NodesInfoRequest extends NodesOperationRequest<NodesInfoRequest> {
         network = true;
         transport = true;
         http = true;
+        plugin = true;
         return this;
     }
 
@@ -200,6 +203,23 @@ public class NodesInfoRequest extends NodesOperationRequest<NodesInfoRequest> {
         return this;
     }
 
+    /**
+     * Should information about plugins be returned
+     * @param plugin true if you want info
+     * @return The request
+     */
+    public NodesInfoRequest plugin(boolean plugin) {
+        this.plugin = plugin;
+        return this;
+    }
+
+    /**
+     * @return true if information about plugins is requested
+     */
+    public boolean plugin() {
+        return plugin;
+    }
+
     @Override
     public void readFrom(StreamInput in) throws IOException {
         super.readFrom(in);
@@ -211,6 +231,7 @@ public class NodesInfoRequest extends NodesOperationRequest<NodesInfoRequest> {
         network = in.readBoolean();
         transport = in.readBoolean();
         http = in.readBoolean();
+        plugin = in.readBoolean();
     }
 
     @Override
@@ -224,5 +245,6 @@ public class NodesInfoRequest extends NodesOperationRequest<NodesInfoRequest> {
         out.writeBoolean(network);
         out.writeBoolean(transport);
         out.writeBoolean(http);
+        out.writeBoolean(plugin);
     }
 }

src/main/java/org/elasticsearch/action/admin/cluster/node/info/NodesInfoRequestBuilder.java

@@ -113,6 +113,10 @@ public class NodesInfoRequestBuilder extends NodesOperationRequestBuilder<NodesI
         return this;
     }
 
+    public NodesInfoRequestBuilder setPlugin(boolean plugin) {
+        request().plugin(plugin);
+        return this;
+    }
 
     @Override
     protected void doExecute(ActionListener<NodesInfoResponse> listener) {

src/main/java/org/elasticsearch/action/admin/cluster/node/info/NodesInfoResponse.java

@@ -27,6 +27,7 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.SettingsFilter;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentFactory;
 
 import java.io.IOException;
 import java.util.Map;
@@ -132,10 +133,26 @@ public class NodesInfoResponse extends NodesOperationResponse<NodeInfo> implemen
             if (nodeInfo.getHttp() != null) {
                 nodeInfo.getHttp().toXContent(builder, params);
             }
+            if (nodeInfo.getPlugins() != null) {
+                nodeInfo.getPlugins().toXContent(builder, params);
+            }
 
             builder.endObject();
         }
         builder.endObject();
         return builder;
     }
+
+    @Override
+    public String toString() {
+        try {
+            XContentBuilder builder = XContentFactory.jsonBuilder().prettyPrint();
+            builder.startObject();
+            toXContent(builder, EMPTY_PARAMS);
+            builder.endObject();
+            return builder.string();
+        } catch (IOException e) {
+            return "{ \"error\" : \"" + e.getMessage() + "\"}";
+        }
+    }
 }

src/main/java/org/elasticsearch/action/admin/cluster/node/info/PluginInfo.java

@@ -0,0 +1,120 @@
+package org.elasticsearch.action.admin.cluster.node.info;
+
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.Streamable;
+import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentBuilderString;
+
+import java.io.IOException;
+import java.io.Serializable;
+
+public class PluginInfo implements Streamable, Serializable, ToXContent {
+    static final class Fields {
+        static final XContentBuilderString NAME = new XContentBuilderString("name");
+        static final XContentBuilderString DESCRIPTION = new XContentBuilderString("description");
+        static final XContentBuilderString URL = new XContentBuilderString("url");
+        static final XContentBuilderString JVM = new XContentBuilderString("jvm");
+        static final XContentBuilderString SITE = new XContentBuilderString("site");
+    }
+
+    private String name;
+    private String description;
+    private boolean site;
+    private boolean jvm;
+
+    public PluginInfo() {
+    }
+
+    /**
+     * Information about plugins
+     * @param name Its name
+     * @param description Its description
+     * @param site true if it's a site plugin
+     * @param jvm true if it's a jvm plugin
+     */
+    public PluginInfo(String name, String description, boolean site, boolean jvm) {
+        this.name = name;
+        this.description = description;
+        this.site = site;
+        this.jvm = jvm;
+    }
+
+    /**
+     * @return Plugin's name
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * @return Plugin's description if any
+     */
+    public String getDescription() {
+        return description;
+    }
+
+    /**
+     * @return true is it's a site plugin
+     */
+    public boolean isSite() {
+        return site;
+    }
+
+    /**
+     * @return true if it's a plugin running in the jvm
+     */
+    public boolean isJvm() {
+        return jvm;
+    }
+
+    /**
+     * We compute the URL for sites: "/_plugin/" + name + "/"
+     * @return
+     */
+    public String getUrl() {
+        if (site) {
+            return ("/_plugin/" + name + "/");
+        } else {
+            return null;
+        }
+    }
+
+    public static PluginInfo readPluginInfo(StreamInput in) throws IOException {
+        PluginInfo info = new PluginInfo();
+        info.readFrom(in);
+        return info;
+    }
+
+    @Override
+    public void readFrom(StreamInput in) throws IOException {
+        this.name = in.readString();
+        this.description = in.readString();
+        this.site = in.readBoolean();
+        this.jvm = in.readBoolean();
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        out.writeString(name);
+        out.writeString(description);
+        out.writeBoolean(site);
+        out.writeBoolean(jvm);
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject();
+        builder.field(Fields.NAME, name);
+        builder.field(Fields.DESCRIPTION, description);
+        if (site) {
+            builder.field(Fields.URL, getUrl());
+        }
+        builder.field(Fields.JVM, jvm);
+        builder.field(Fields.SITE, site);
+        builder.endObject();
+
+        return builder;
+    }
+}

src/main/java/org/elasticsearch/action/admin/cluster/node/info/PluginsInfo.java

@@ -0,0 +1,70 @@
+package org.elasticsearch.action.admin.cluster.node.info;
+
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.Streamable;
+import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentBuilderString;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+
+public class PluginsInfo implements Streamable, Serializable, ToXContent {
+    static final class Fields {
+        static final XContentBuilderString PLUGINS = new XContentBuilderString("plugins");
+    }
+
+    private List<PluginInfo> infos;
+
+    public PluginsInfo() {
+        infos = new ArrayList<PluginInfo>();
+    }
+
+    public PluginsInfo(int size) {
+        infos = new ArrayList<PluginInfo>(size);
+    }
+
+    public List<PluginInfo> getInfos() {
+        return infos;
+    }
+
+    public void add(PluginInfo info) {
+        infos.add(info);
+    }
+
+    public static PluginsInfo readPluginsInfo(StreamInput in) throws IOException {
+        PluginsInfo infos = new PluginsInfo();
+        infos.readFrom(in);
+        return infos;
+    }
+
+    @Override
+    public void readFrom(StreamInput in) throws IOException {
+        int plugins_size = in.readInt();
+        for (int i = 0; i < plugins_size; i++) {
+            infos.add(PluginInfo.readPluginInfo(in));
+        }
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        out.writeInt(infos.size());
+        for (PluginInfo plugin : infos) {
+            plugin.writeTo(out);
+        }
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startArray(Fields.PLUGINS);
+        for (PluginInfo pluginInfo : infos) {
+            pluginInfo.toXContent(builder, params);
+        }
+        builder.endArray();
+
+        return builder;
+    }
+}

src/main/java/org/elasticsearch/action/admin/cluster/node/info/TransportNodesInfoAction.java

@@ -97,7 +97,8 @@ public class TransportNodesInfoAction extends TransportNodesOperationAction<Node
     @Override
     protected NodeInfo nodeOperation(NodeInfoRequest nodeRequest) throws ElasticSearchException {
         NodesInfoRequest request = nodeRequest.request;
-        return nodeService.info(request.settings(), request.os(), request.process(), request.jvm(), request.threadPool(), request.network(), request.transport(), request.http());
+        return nodeService.info(request.settings(), request.os(), request.process(), request.jvm(), request.threadPool(),
+                request.network(), request.transport(), request.http(), request.plugin());
     }
 
     @Override

src/main/java/org/elasticsearch/node/service/NodeService.java

@@ -34,6 +34,7 @@ import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.http.HttpServer;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.monitor.MonitorService;
+import org.elasticsearch.plugins.PluginsService;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
@@ -53,6 +54,8 @@ public class NodeService extends AbstractComponent {
 
     private final IndicesService indicesService;
 
+    private final PluginsService pluginService;
+
     @Nullable
     private HttpServer httpServer;
 
@@ -64,7 +67,9 @@ public class NodeService extends AbstractComponent {
     private final Version version;
 
     @Inject
-    public NodeService(Settings settings, ThreadPool threadPool, MonitorService monitorService, Discovery discovery, ClusterService clusterService, TransportService transportService, IndicesService indicesService) {
+    public NodeService(Settings settings, ThreadPool threadPool, MonitorService monitorService, Discovery discovery,
+                       ClusterService clusterService, TransportService transportService, IndicesService indicesService,
+                       PluginsService pluginService) {
         super(settings);
         this.threadPool = threadPool;
         this.monitorService = monitorService;
@@ -77,6 +82,7 @@ public class NodeService extends AbstractComponent {
             this.hostname = address.getHostName();
         }
         this.version = Version.CURRENT;
+        this.pluginService = pluginService;
     }
 
     public void setHttpServer(@Nullable HttpServer httpServer) {
@@ -117,11 +123,13 @@ public class NodeService extends AbstractComponent {
                 threadPool.info(),
                 monitorService.networkService().info(),
                 transportService.info(),
-                httpServer == null ? null : httpServer.info()
+                httpServer == null ? null : httpServer.info(),
+                pluginService == null ? null : pluginService.info()
         );
     }
 
-    public NodeInfo info(boolean settings, boolean os, boolean process, boolean jvm, boolean threadPool, boolean network, boolean transport, boolean http) {
+    public NodeInfo info(boolean settings, boolean os, boolean process, boolean jvm, boolean threadPool,
+                         boolean network, boolean transport, boolean http, boolean plugin) {
         return new NodeInfo(hostname, version, clusterService.state().nodes().localNode(), serviceAttributes,
                 settings ? this.settings : null,
                 os ? monitorService.osService().info() : null,
@@ -130,7 +138,8 @@ public class NodeService extends AbstractComponent {
                 threadPool ? this.threadPool.info() : null,
                 network ? monitorService.networkService().info() : null,
                 transport ? transportService.info() : null,
-                http ? (httpServer == null ? null : httpServer.info()) : null
+                http ? (httpServer == null ? null : httpServer.info()) : null,
+                plugin ? (pluginService == null ? null : pluginService.info()) : null
         );
     }
 

src/main/java/org/elasticsearch/plugins/PluginsService.java

@@ -19,11 +19,10 @@
 
 package org.elasticsearch.plugins;
 
-import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Lists;
-import com.google.common.collect.Maps;
-import com.google.common.collect.Sets;
+import com.google.common.collect.*;
 import org.elasticsearch.ElasticSearchException;
+import org.elasticsearch.action.admin.cluster.node.info.PluginInfo;
+import org.elasticsearch.action.admin.cluster.node.info.PluginsInfo;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.collect.MapBuilder;
 import org.elasticsearch.common.component.AbstractComponent;
@@ -31,10 +30,12 @@ import org.elasticsearch.common.component.LifecycleComponent;
 import org.elasticsearch.common.inject.Module;
 import org.elasticsearch.common.settings.ImmutableSettings;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.env.Environment;
 import org.elasticsearch.index.CloseableIndexComponent;
 
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.lang.reflect.Method;
@@ -47,6 +48,7 @@ import static com.google.common.collect.Maps.newHashMap;
  *
  */
 public class PluginsService extends AbstractComponent {
+    private static final String ES_PLUGIN_PROPERTIES = "es-plugin.properties";
 
     private final Environment environment;
 
@@ -54,6 +56,10 @@ public class PluginsService extends AbstractComponent {
 
     private final ImmutableMap<Plugin, List<OnModuleReference>> onModuleReferences;
 
+    private PluginsInfo cachedPluginsInfo;
+    private final TimeValue refreshInterval;
+    private long lastRefresh;
+
     static class OnModuleReference {
         public final Class<? extends Module> moduleClass;
         public final Method onModuleMethod;
@@ -128,6 +134,9 @@ public class PluginsService extends AbstractComponent {
             }
         }
         this.onModuleReferences = onModuleReferences.immutableMap();
+
+        this.refreshInterval = componentSettings.getAsTime("info_refresh_interval", TimeValue.timeValueSeconds(10));
+
     }
 
     public ImmutableMap<String, Plugin> plugins() {
@@ -240,6 +249,93 @@ public class PluginsService extends AbstractComponent {
         return services;
     }
 
+    /**
+     * Get information about plugins (jvm and site plugins).
+     * Information are cached for 10 seconds by default. Modify `plugins.info_refresh_interval` property if needed.
+     * Setting `plugins.info_refresh_interval` to `-1` will cause infinite caching.
+     * Setting `plugins.info_refresh_interval` to `0` will disable caching.
+     * @return List of plugins information
+     */
+    synchronized public PluginsInfo info() {
+        if (refreshInterval.millis() != 0) {
+            if (cachedPluginsInfo != null &&
+                    (refreshInterval.millis() < 0 || (System.currentTimeMillis() - lastRefresh) < refreshInterval.millis())) {
+                if (logger.isTraceEnabled()) logger.trace("using cache to retrieve plugins info");
+                return cachedPluginsInfo;
+            }
+            lastRefresh = System.currentTimeMillis();
+        }
+
+        if (logger.isTraceEnabled()) logger.trace("starting to fetch info on plugins");
+        cachedPluginsInfo = new PluginsInfo();
+
+        // We create a map to have only unique values
+        Set<String> plugins = new HashSet<String>();
+
+        for (Plugin plugin : plugins().values()) {
+            // We should detect if the plugin has also an embedded _site structure
+            File siteFile = new File(new File(environment.pluginsFile(), plugin.name()), "_site");
+            boolean isSite = siteFile.exists() && siteFile.isDirectory();
+            if (logger.isTraceEnabled()) logger.trace("found a jvm plugin [{}], [{}]{}",
+                    plugin.name(), plugin.description(), isSite ? ": with _site structure" : "");
+            cachedPluginsInfo.add(new PluginInfo(plugin.name(), plugin.description(), isSite, true));
+            plugins.add(plugin.name());
+        }
+
+        File pluginsFile = environment.pluginsFile();
+        if (!pluginsFile.exists()) {
+            return cachedPluginsInfo;
+        }
+        if (!pluginsFile.isDirectory()) {
+            return cachedPluginsInfo;
+        }
+
+        File[] pluginsFiles = pluginsFile.listFiles();
+        if (pluginsFiles != null) {
+            for (File plugin : pluginsFiles) {
+                // We skip already known jvm plugins
+                if (!plugins.contains(plugin.getName())) {
+                    File sitePluginDir = new File(plugin, "_site");
+                    if (sitePluginDir.exists()) {
+                        String name = plugin.getName();
+                        String description = "No description found for " + name + ".";
+
+                        // We check if es-plugin.properties exists in plugin/_site dir
+                        File pluginPropFile = new File(sitePluginDir, ES_PLUGIN_PROPERTIES);
+                        if (pluginPropFile.exists()) {
+
+                            Properties pluginProps = new Properties();
+                            InputStream is = null;
+                            try {
+                                is = new FileInputStream(pluginPropFile.getAbsolutePath());
+                                pluginProps.load(is);
+                                description = pluginProps.getProperty("description");
+                            } catch (Exception e) {
+                                logger.warn("failed to load plugin description from [" +
+                                        pluginPropFile.getAbsolutePath() + "]", e);
+                            } finally {
+                                if (is != null) {
+                                    try {
+                                        is.close();
+                                    } catch (IOException e) {
+                                        // ignore
+                                    }
+                                }
+                            }
+                        }
+
+                        if (logger.isTraceEnabled()) logger.trace("found a site plugin [{}], [{}]",
+                                name, description);
+                        cachedPluginsInfo.add(new PluginInfo(name, description, true, false));
+                    }
+                }
+            }
+        }
+
+
+        return cachedPluginsInfo;
+    }
+
     private void loadPluginsIntoClassLoader() {
         File pluginsFile = environment.pluginsFile();
         if (!pluginsFile.exists()) {
@@ -302,7 +398,7 @@ public class PluginsService extends AbstractComponent {
         Map<String, Plugin> plugins = newHashMap();
         Enumeration<URL> pluginUrls = null;
         try {
-            pluginUrls = settings.getClassLoader().getResources("es-plugin.properties");
+            pluginUrls = settings.getClassLoader().getResources(ES_PLUGIN_PROPERTIES);
         } catch (IOException e) {
             logger.warn("failed to find plugins from classpath", e);
             return ImmutableMap.of();

src/main/java/org/elasticsearch/rest/action/admin/cluster/node/info/RestNodesInfoAction.java

@@ -73,6 +73,9 @@ public class RestNodesInfoAction extends BaseRestHandler {
         controller.registerHandler(RestRequest.Method.GET, "/_nodes/http", new RestHttpHandler());
         controller.registerHandler(RestRequest.Method.GET, "/_nodes/{nodeId}/http", new RestHttpHandler());
 
+        controller.registerHandler(RestRequest.Method.GET, "/_nodes/plugin", new RestPluginHandler());
+        controller.registerHandler(RestRequest.Method.GET, "/_nodes/{nodeId}/plugin", new RestPluginHandler());
+
         this.settingsFilter = settingsFilter;
     }
 
@@ -97,6 +100,7 @@ public class RestNodesInfoAction extends BaseRestHandler {
         nodesInfoRequest.network(request.paramAsBoolean("network", nodesInfoRequest.network()));
         nodesInfoRequest.transport(request.paramAsBoolean("transport", nodesInfoRequest.transport()));
         nodesInfoRequest.http(request.paramAsBoolean("http", nodesInfoRequest.http()));
+        nodesInfoRequest.plugin(request.paramAsBoolean("plugin", nodesInfoRequest.plugin()));
 
         executeNodeRequest(request, channel, nodesInfoRequest);
     }
@@ -201,4 +205,13 @@ public class RestNodesInfoAction extends BaseRestHandler {
             executeNodeRequest(request, channel, nodesInfoRequest);
         }
     }
+
+    class RestPluginHandler implements RestHandler {
+        @Override
+        public void handleRequest(final RestRequest request, final RestChannel channel) {
+            NodesInfoRequest nodesInfoRequest = new NodesInfoRequest(RestActions.splitNodes(request.param("nodeId")));
+            nodesInfoRequest.clear().plugin(true);
+            executeNodeRequest(request, channel, nodesInfoRequest);
+        }
+    }
 }

src/test/java/org/elasticsearch/test/integration/nodesinfo/SimpleNodesInfoTests.java

@@ -21,23 +21,39 @@ package org.elasticsearch.test.integration.nodesinfo;
 
 import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.action.admin.cluster.node.info.NodesInfoResponse;
+import org.elasticsearch.action.admin.cluster.node.info.PluginInfo;
+import org.elasticsearch.action.admin.cluster.node.info.PluginsInfo;
 import org.elasticsearch.cluster.ClusterService;
+import org.elasticsearch.common.settings.ImmutableSettings;
 import org.elasticsearch.node.internal.InternalNode;
 import org.elasticsearch.test.integration.AbstractNodesTests;
+import org.elasticsearch.test.integration.nodesinfo.plugin.dummy1.TestPlugin;
+import org.elasticsearch.test.integration.nodesinfo.plugin.dummy2.TestNoVersionPlugin;
 import org.testng.annotations.AfterMethod;
 import org.testng.annotations.Test;
 
+import java.io.File;
+import java.net.URISyntaxException;
+import java.net.URL;
+
 import static org.elasticsearch.client.Requests.clusterHealthRequest;
 import static org.elasticsearch.client.Requests.nodesInfoRequest;
+import static org.elasticsearch.common.settings.ImmutableSettings.settingsBuilder;
 import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.notNullValue;
+import static org.hamcrest.Matchers.*;
 
 /**
  *
  */
 public class SimpleNodesInfoTests extends AbstractNodesTests {
 
+    static final class Fields {
+        static final String SITE_PLUGIN = "dummy";
+        static final String SITE_PLUGIN_DESCRIPTION = "This is a description for a dummy test site plugin.";
+        static final String SITE_PLUGIN_NO_DESCRIPTION = "No description found for dummy.";
+        static final String JVM_PLUGIN_NO_DESCRIPTION = "No description found for test-no-version-plugin.";
+    }
+
     @AfterMethod
     public void closeNodes() {
         closeAllNodes();
@@ -81,4 +97,112 @@ public class SimpleNodesInfoTests extends AbstractNodesTests {
         assertThat(response.getNodes().length, equalTo(1));
         assertThat(response.getNodesMap().get(server2NodeId), notNullValue());
     }
+
+    /**
+     * Use case is to start 4 nodes:
+     * <ul>
+     *     <li>1 : no plugin</li>
+     *     <li>2 : one site plugin (with a es-plugin.properties file)</li>
+     *     <li>3 : one java plugin</li>
+     *     <li>4 : one site plugin and 2 java plugins (included the previous one)</li>
+     * </ul>
+     * We test here that NodeInfo API with plugin option give us the right results.
+     * @throws URISyntaxException
+     */
+    @Test
+    public void testNodeInfoPlugin() throws URISyntaxException {
+        // We start four nodes
+        // The first has no plugin
+        String server1NodeId = startNodeWithPlugins("node1");
+        // The second has one site plugin with a es-plugin.properties file (description and version)
+        String server2NodeId = startNodeWithPlugins("node2");
+        // The third has one java plugin
+        String server3NodeId = startNodeWithPlugins("node3");
+        // The fourth has one java plugin and one site plugin
+        String server4NodeId = startNodeWithPlugins("node4");
+
+        ClusterHealthResponse clusterHealth = client("node4").admin().cluster().health(clusterHealthRequest().waitForGreenStatus()).actionGet();
+        logger.info("--> done cluster_health, status " + clusterHealth.getStatus());
+
+        NodesInfoResponse response = client("node1").admin().cluster().prepareNodesInfo().setPlugin(true).execute().actionGet();
+        logger.info("--> full json answer, status " + response.toString());
+
+        checkPlugin(response, server1NodeId, 0, 0);
+        checkPlugin(response, server2NodeId, 1, 0);
+        checkPlugin(response, server3NodeId, 0, 1);
+        checkPlugin(response, server4NodeId, 1, 2); // Note that we have now 2 JVM plugins as we have already loaded one with node3
+    }
+
+    /**
+     * We check infos
+     * @param response Response
+     * @param nodeId NodeId we want to check
+     * @param expectedSitePlugins Number of site plugins expected
+     * @param expectedJvmPlugins Number of jvm plugins expected
+     */
+    private void checkPlugin(NodesInfoResponse response, String nodeId,
+                             int expectedSitePlugins, int expectedJvmPlugins) {
+        assertThat(response.getNodesMap().get(nodeId), notNullValue());
+
+        PluginsInfo plugins = response.getNodesMap().get(nodeId).getPlugins();
+        assertThat(plugins, notNullValue());
+
+        int num_site_plugins = 0;
+        int num_jvm_plugins = 0;
+
+        for (PluginInfo pluginInfo : plugins.getInfos()) {
+            // It should be a site or a jvm plugin
+            assertThat(pluginInfo.isJvm() || pluginInfo.isSite(), is(true));
+
+            if (pluginInfo.isSite() && !pluginInfo.isJvm()) {
+                // Let's do some tests for site plugins
+                assertThat(pluginInfo.getName(), isOneOf(Fields.SITE_PLUGIN,
+                        TestNoVersionPlugin.Fields.NAME));
+                assertThat(pluginInfo.getDescription(),
+                        isOneOf(Fields.SITE_PLUGIN_DESCRIPTION,
+                                Fields.SITE_PLUGIN_NO_DESCRIPTION,
+                                Fields.JVM_PLUGIN_NO_DESCRIPTION));
+                assertThat(pluginInfo.getUrl(), notNullValue());
+                num_site_plugins++;
+            }
+
+            if (pluginInfo.isJvm() && !pluginInfo.isSite()) {
+                // Let's do some tests for site plugins
+                assertThat(pluginInfo.getName(),
+                        isOneOf(TestPlugin.Fields.NAME, TestNoVersionPlugin.Fields.NAME));
+                assertThat(pluginInfo.getDescription(),
+                        isOneOf(TestPlugin.Fields.DESCRIPTION, TestNoVersionPlugin.Fields.DESCRIPTION));
+                assertThat(pluginInfo.getUrl(), nullValue());
+                num_jvm_plugins++;
+            }
+
+            // On node4, test-no-version-plugin has an embedded _site structure
+            if (pluginInfo.isJvm() && pluginInfo.isSite()) {
+                assertThat(pluginInfo.getName(),
+                        is(TestNoVersionPlugin.Fields.NAME));
+                assertThat(pluginInfo.getDescription(),
+                        is(TestNoVersionPlugin.Fields.DESCRIPTION));
+                assertThat(pluginInfo.getUrl(), notNullValue());
+                num_jvm_plugins++;
+            }
+        }
+
+        assertThat(num_site_plugins, is(expectedSitePlugins));
+        assertThat(num_jvm_plugins, is(expectedJvmPlugins));
+    }
+
+    private String startNodeWithPlugins(String name) throws URISyntaxException {
+        URL resource = SimpleNodesInfoTests.class.getResource("/org/elasticsearch/test/integration/nodesinfo/" + name + "/");
+        ImmutableSettings.Builder settings = settingsBuilder();
+        if (resource != null) {
+            settings.put("path.plugins", new File(resource.toURI()).getAbsolutePath());
+        }
+
+        startNode(name, settings);
+        String serverNodeId = ((InternalNode) node(name)).injector()
+                .getInstance(ClusterService.class).state().nodes().localNodeId();
+        logger.debug("--> server {} started" + serverNodeId);
+        return serverNodeId;
+    }
+
 }

src/test/java/org/elasticsearch/test/integration/nodesinfo/plugin/dummy1/TestPlugin.java

@@ -0,0 +1,40 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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.elasticsearch.test.integration.nodesinfo.plugin.dummy1;
+
+import org.elasticsearch.plugins.AbstractPlugin;
+
+public class TestPlugin extends AbstractPlugin {
+
+    static final public class Fields {
+        static public final String NAME = "test-plugin";
+        static public final String DESCRIPTION = NAME + " description";
+    }
+
+    @Override
+    public String name() {
+        return Fields.NAME;
+    }
+
+    @Override
+    public String description() {
+        return Fields.DESCRIPTION;
+    }
+}

src/test/java/org/elasticsearch/test/integration/nodesinfo/plugin/dummy2/TestNoVersionPlugin.java

@@ -0,0 +1,40 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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.elasticsearch.test.integration.nodesinfo.plugin.dummy2;
+
+import org.elasticsearch.plugins.AbstractPlugin;
+
+public class TestNoVersionPlugin extends AbstractPlugin {
+
+    static final public class Fields {
+        static public final String NAME = "test-no-version-plugin";
+        static public final String DESCRIPTION = NAME + " description";
+    }
+
+    @Override
+    public String name() {
+        return Fields.NAME;
+    }
+
+    @Override
+    public String description() {
+        return Fields.DESCRIPTION;
+    }
+}

src/test/resources/org/elasticsearch/test/integration/nodesinfo/node2/dummy/_site/es-plugin.properties

@@ -0,0 +1,20 @@
+################################################################
+# Licensed to ElasticSearch and Shay Banon under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. ElasticSearch licenses this
+# file to you 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.
+################################################################
+description=This is a description for a dummy test site plugin.
+

src/test/resources/org/elasticsearch/test/integration/nodesinfo/node2/dummy/_site/index.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Dummy Site Plugin on Node 3</title>
+</head>
+<body>
+<p>Welcome to this dummy elasticsearch plugin</p>
+</body>
+</html>

src/test/resources/org/elasticsearch/test/integration/nodesinfo/node3/test-plugin/es-plugin.properties

@@ -0,0 +1,20 @@
+################################################################
+# Licensed to ElasticSearch and Shay Banon under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. ElasticSearch licenses this
+# file to you 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.
+################################################################
+plugin=org.elasticsearch.test.integration.nodesinfo.plugin.dummy1.TestPlugin
+

src/test/resources/org/elasticsearch/test/integration/nodesinfo/node4/dummy/_site/index.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Dummy Site Plugin on Node 3</title>
+</head>
+<body>
+<p>Welcome to this dummy elasticsearch plugin</p>
+</body>
+</html>

src/test/resources/org/elasticsearch/test/integration/nodesinfo/node4/test-no-version-plugin/_site/index.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Dummy Site Plugin on Node 3</title>
+</head>
+<body>
+<p>Welcome to this dummy elasticsearch plugin</p>
+</body>
+</html>

src/test/resources/org/elasticsearch/test/integration/nodesinfo/node4/test-no-version-plugin/es-plugin.properties

@@ -0,0 +1,19 @@
+################################################################
+# Licensed to ElasticSearch and Shay Banon under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. ElasticSearch licenses this
+# file to you 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.
+################################################################
+plugin=org.elasticsearch.test.integration.nodesinfo.plugin.dummy2.TestNoVersionPlugin