Add a Painless Context REST API

client/rest-high-level/src/test/java/org/elasticsearch/client/RestHighLevelClientTests.java

@@ -713,6 +713,7 @@ public void testApiNamingConventions() throws Exception {
             "nodes.hot_threads",
             "nodes.usage",
             "nodes.reload_secure_settings",
+            "scripts_painless_context",
             "search_shards",
         };
         List<String> booleanReturnMethods = Arrays.asList(

modules/lang-painless/src/main/java/org/elasticsearch/painless/PainlessPlugin.java

@@ -20,15 +20,18 @@
 package org.elasticsearch.painless;
 
 
+import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.action.ActionRequest;
 import org.elasticsearch.action.ActionResponse;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
+import org.elasticsearch.common.inject.Module;
 import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.SettingsFilter;
+import org.elasticsearch.painless.action.PainlessContextAction;
 import org.elasticsearch.painless.spi.PainlessExtension;
 import org.elasticsearch.painless.spi.Whitelist;
 import org.elasticsearch.painless.spi.WhitelistLoader;
@@ -81,6 +84,8 @@ public final class PainlessPlugin extends Plugin implements ScriptPlugin, Extens
         whitelists = map;
     }
 
+    private final SetOnce<PainlessScriptEngine> painlessScriptEngine = new SetOnce<>();
+
     @Override
     public ScriptEngine getScriptEngine(Settings settings, Collection<ScriptContext<?>> contexts) {
         Map<ScriptContext<?>, List<Whitelist>> contextsWithWhitelists = new HashMap<>();
@@ -92,7 +97,13 @@ public ScriptEngine getScriptEngine(Settings settings, Collection<ScriptContext<
             }
             contextsWithWhitelists.put(context, contextWhitelists);
         }
-        return new PainlessScriptEngine(settings, contextsWithWhitelists);
+        painlessScriptEngine.set(new PainlessScriptEngine(settings, contextsWithWhitelists));
+        return painlessScriptEngine.get();
+    }
+
+    @Override
+    public Collection<Module> createGuiceModules() {
+        return Collections.singleton(b -> b.bind(PainlessScriptEngine.class).toInstance(painlessScriptEngine.get()));
     }
 
     @Override
@@ -118,16 +129,20 @@ public List<ScriptContext<?>> getContexts() {
 
     @Override
     public List<ActionHandler<? extends ActionRequest, ? extends ActionResponse>> getActions() {
-        return Collections.singletonList(
-            new ActionHandler<>(PainlessExecuteAction.INSTANCE, PainlessExecuteAction.TransportAction.class)
-        );
+        List<ActionHandler<? extends ActionRequest, ? extends ActionResponse>> actions = new ArrayList<>();
+        actions.add(new ActionHandler<>(PainlessExecuteAction.INSTANCE, PainlessExecuteAction.TransportAction.class));
+        actions.add(new ActionHandler<>(PainlessContextAction.INSTANCE, PainlessContextAction.TransportAction.class));
+        return actions;
     }
 
     @Override
     public List<RestHandler> getRestHandlers(Settings settings, RestController restController, ClusterSettings clusterSettings,
                                              IndexScopedSettings indexScopedSettings, SettingsFilter settingsFilter,
                                              IndexNameExpressionResolver indexNameExpressionResolver,
                                              Supplier<DiscoveryNodes> nodesInCluster) {
-        return Collections.singletonList(new PainlessExecuteAction.RestAction(settings, restController));
+        List<RestHandler> handlers = new ArrayList<>();
+        handlers.add(new PainlessExecuteAction.RestAction(settings, restController));
+        handlers.add(new PainlessContextAction.RestAction(settings, restController));
+        return handlers;
     }
 }

modules/lang-painless/src/main/java/org/elasticsearch/painless/PainlessScriptEngine.java

@@ -22,6 +22,7 @@
 import org.elasticsearch.SpecialPermission;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.painless.Compiler.Loader;
+import org.elasticsearch.painless.lookup.PainlessLookup;
 import org.elasticsearch.painless.lookup.PainlessLookupBuilder;
 import org.elasticsearch.painless.spi.Whitelist;
 import org.elasticsearch.script.ScriptContext;
@@ -82,6 +83,7 @@ public final class PainlessScriptEngine implements ScriptEngine {
     private final CompilerSettings defaultCompilerSettings = new CompilerSettings();
 
     private final Map<ScriptContext<?>, Compiler> contextsToCompilers;
+    private final Map<ScriptContext<?>, PainlessLookup> contextsToLookups;
 
     /**
      * Constructor.
@@ -91,14 +93,22 @@ public PainlessScriptEngine(Settings settings, Map<ScriptContext<?>, List<Whitel
         defaultCompilerSettings.setRegexesEnabled(CompilerSettings.REGEX_ENABLED.get(settings));
 
         Map<ScriptContext<?>, Compiler> contextsToCompilers = new HashMap<>();
+        Map<ScriptContext<?>, PainlessLookup> contextsToLookups = new HashMap<>();
 
         for (Map.Entry<ScriptContext<?>, List<Whitelist>> entry : contexts.entrySet()) {
             ScriptContext<?> context = entry.getKey();
-            contextsToCompilers.put(context, new Compiler(context.instanceClazz, context.factoryClazz, context.statefulFactoryClazz,
-                    PainlessLookupBuilder.buildFromWhitelists(entry.getValue())));
+            PainlessLookup lookup = PainlessLookupBuilder.buildFromWhitelists(entry.getValue());
+            contextsToCompilers.put(context,
+                    new Compiler(context.instanceClazz, context.factoryClazz, context.statefulFactoryClazz, lookup));
+            contextsToLookups.put(context, lookup);
         }
 
         this.contextsToCompilers = Collections.unmodifiableMap(contextsToCompilers);
+        this.contextsToLookups = Collections.unmodifiableMap(contextsToLookups);
+    }
+
+    public Map<ScriptContext<?>, PainlessLookup> getContextsToLookups() {
+        return contextsToLookups;
     }
 
     /**

modules/lang-painless/src/main/java/org/elasticsearch/painless/action/PainlessContextAction.java

@@ -0,0 +1,236 @@
+/*
+ * Licensed to Elasticsearch 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.painless.action;
+
+import org.elasticsearch.action.Action;
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.ActionRequest;
+import org.elasticsearch.action.ActionRequestValidationException;
+import org.elasticsearch.action.ActionResponse;
+import org.elasticsearch.action.support.ActionFilters;
+import org.elasticsearch.action.support.HandledTransportAction;
+import org.elasticsearch.client.node.NodeClient;
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.painless.PainlessScriptEngine;
+import org.elasticsearch.painless.lookup.PainlessLookup;
+import org.elasticsearch.rest.BaseRestHandler;
+import org.elasticsearch.rest.RestController;
+import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.action.RestToXContentListener;
+import org.elasticsearch.script.ScriptContext;
+import org.elasticsearch.tasks.Task;
+import org.elasticsearch.transport.TransportService;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import static org.elasticsearch.rest.RestRequest.Method.GET;
+
+/**
+ * Internal REST API for querying context information about Painless whitelists.
+ * Commands include the following:
+ * <ul>
+ *     <li> GET /_scripts/painless/_context -- retrieves a list of contexts </li>
+ *     <li> GET /_scripts/painless/_context?context=%name% --
+ *     retrieves all available information about the API for this specific context</li>
+ * </ul>
+ */
+public class PainlessContextAction extends Action<PainlessContextAction.Response> {
+
+    public static final PainlessContextAction INSTANCE = new PainlessContextAction();
+    private static final String NAME = "cluster:admin/scripts/painless/context";
+
+    private static final String SCRIPT_CONTEXT_NAME_PARAM = "context";
+
+    private PainlessContextAction() {
+        super(NAME);
+    }
+
+    @Override
+    public Response newResponse() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Writeable.Reader<Response> getResponseReader() {
+        return Response::new;
+    }
+
+    public static class Request extends ActionRequest {
+
+        private String scriptContextName;
+
+        public Request() {
+            scriptContextName = null;
+        }
+
+        public Request(StreamInput in) throws IOException {
+            super(in);
+            scriptContextName = in.readString();
+        }
+
+        public void setScriptContextName(String scriptContextName) {
+            this.scriptContextName = scriptContextName;
+        }
+
+        public String getScriptContextName() {
+            return scriptContextName;
+        }
+
+        @Override
+        public ActionRequestValidationException validate() {
+            return null;
+        }
+
+        @Override
+        public void readFrom(StreamInput in) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            out.writeString(scriptContextName);
+        }
+    }
+
+    public static class Response extends ActionResponse implements ToXContentObject {
+
+        public static final ParseField CONTEXTS = new ParseField("contexts");
+
+        private final List<String> scriptContextNames;
+        private final PainlessContextInfo painlessContextInfo;
+
+        public Response(List<String> scriptContextNames, PainlessContextInfo painlessContextInfo) {
+            Objects.requireNonNull(scriptContextNames);
+            scriptContextNames = new ArrayList<>(scriptContextNames);
+            scriptContextNames.sort(String::compareTo);
+            this.scriptContextNames = Collections.unmodifiableList(scriptContextNames);
+            this.painlessContextInfo = painlessContextInfo;
+        }
+
+        public Response(StreamInput in) throws IOException {
+            super(in);
+            scriptContextNames = in.readStringList();
+            painlessContextInfo = in.readOptionalWriteable(PainlessContextInfo::new);
+        }
+
+        @Override
+        public void readFrom(StreamInput in) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            out.writeStringCollection(scriptContextNames);
+            out.writeOptionalWriteable(painlessContextInfo);
+        }
+
+        @Override
+        public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+            if (painlessContextInfo == null) {
+                builder.startObject();
+                builder.field(CONTEXTS.getPreferredName(), scriptContextNames);
+                builder.endObject();
+            } else {
+                painlessContextInfo.toXContent(builder, params);
+            }
+
+            return builder;
+        }
+    }
+
+    public static class TransportAction extends HandledTransportAction<Request, Response> {
+
+        private final PainlessScriptEngine painlessScriptEngine;
+
+        @Inject
+        public TransportAction(TransportService transportService, ActionFilters actionFilters, PainlessScriptEngine painlessScriptEngine) {
+            super(NAME, transportService, actionFilters, (Writeable.Reader<Request>)Request::new);
+            this.painlessScriptEngine = painlessScriptEngine;
+        }
+
+        @Override
+        protected void doExecute(Task task, Request request, ActionListener<Response> listener) {
+            List<String> scriptContextNames;
+            PainlessContextInfo painlessContextInfo;
+
+            if (request.scriptContextName == null) {
+                scriptContextNames =
+                        painlessScriptEngine.getContextsToLookups().keySet().stream().map(v -> v.name).collect(Collectors.toList());
+                painlessContextInfo = null;
+            } else {
+                ScriptContext<?> scriptContext = null;
+                PainlessLookup painlessLookup = null;
+
+                for (Map.Entry<ScriptContext<?>, PainlessLookup> contextLookupEntry :
+                        painlessScriptEngine.getContextsToLookups().entrySet()) {
+                    if (contextLookupEntry.getKey().name.equals(request.getScriptContextName())) {
+                        scriptContext = contextLookupEntry.getKey();
+                        painlessLookup = contextLookupEntry.getValue();
+                        break;
+                    }
+                }
+
+                if (scriptContext == null || painlessLookup == null) {
+                    throw new IllegalArgumentException("script context [" + request.getScriptContextName() + "] not found");
+                }
+
+                scriptContextNames = Collections.emptyList();
+                painlessContextInfo = new PainlessContextInfo(scriptContext, painlessLookup);
+            }
+
+            listener.onResponse(new Response(scriptContextNames, painlessContextInfo));
+        }
+    }
+
+    public static class RestAction extends BaseRestHandler {
+
+        public RestAction(Settings settings, RestController controller) {
+            super(settings);
+            controller.registerHandler(GET, "/_scripts/painless/_context", this);
+        }
+
+        @Override
+        public String getName() {
+            return "_scripts_painless_context";
+        }
+
+        @Override
+        protected RestChannelConsumer prepareRequest(RestRequest restRequest, NodeClient client) {
+            Request request = new Request();
+            request.setScriptContextName(restRequest.param(SCRIPT_CONTEXT_NAME_PARAM));
+            return channel -> client.executeLocally(INSTANCE, request, new RestToXContentListener<>(channel));
+        }
+    }
+}