Reintroduce system index APIs for Kibana (#54935)

This change reintroduces the system index APIs for Kibana without the
changes made for marking what system indices could be accessed using
these APIs. In essence, this is a partial revert of #53912. The changes
for marking what system indices should be allowed access will be
handled in a separate change.

The APIs introduced here are wrapped versions of the existing REST
endpoints. A new setting is also introduced since the Kibana system
indices' names are allowed to be changed by a user in case multiple
instances of Kibana use the same instance of Elasticsearch.

Relates #52385
Backport of #54858

modules/kibana/build.gradle

@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+
+esplugin {
+  description 'Plugin exposing APIs for Kibana system indices'
+  classname 'org.elasticsearch.kibana.KibanaPlugin'
+}
+
+dependencies {
+  compile project(path: ':modules:reindex', configuration: 'runtime')
+}
+
+testClusters.integTest {
+  module file(project(':modules:reindex').tasks.bundlePlugin.archiveFile)
+}

modules/kibana/src/main/java/org/elasticsearch/kibana/KibanaPlugin.java

@@ -0,0 +1,151 @@
+/*
+ * 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.kibana;
+
+import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
+import org.elasticsearch.cluster.node.DiscoveryNodes;
+import org.elasticsearch.common.settings.ClusterSettings;
+import org.elasticsearch.common.settings.IndexScopedSettings;
+import org.elasticsearch.common.settings.Setting;
+import org.elasticsearch.common.settings.Setting.Property;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.settings.SettingsFilter;
+import org.elasticsearch.index.reindex.RestDeleteByQueryAction;
+import org.elasticsearch.indices.SystemIndexDescriptor;
+import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.plugins.SystemIndexPlugin;
+import org.elasticsearch.rest.BaseRestHandler;
+import org.elasticsearch.rest.RestController;
+import org.elasticsearch.rest.RestHandler;
+import org.elasticsearch.rest.action.admin.indices.RestCreateIndexAction;
+import org.elasticsearch.rest.action.admin.indices.RestGetAliasesAction;
+import org.elasticsearch.rest.action.admin.indices.RestGetIndicesAction;
+import org.elasticsearch.rest.action.admin.indices.RestIndexPutAliasAction;
+import org.elasticsearch.rest.action.admin.indices.RestRefreshAction;
+import org.elasticsearch.rest.action.admin.indices.RestUpdateSettingsAction;
+import org.elasticsearch.rest.action.document.RestBulkAction;
+import org.elasticsearch.rest.action.document.RestDeleteAction;
+import org.elasticsearch.rest.action.document.RestGetAction;
+import org.elasticsearch.rest.action.document.RestIndexAction;
+import org.elasticsearch.rest.action.document.RestIndexAction.AutoIdHandler;
+import org.elasticsearch.rest.action.document.RestIndexAction.CreateHandler;
+import org.elasticsearch.rest.action.document.RestMultiGetAction;
+import org.elasticsearch.rest.action.document.RestUpdateAction;
+import org.elasticsearch.rest.action.search.RestClearScrollAction;
+import org.elasticsearch.rest.action.search.RestSearchAction;
+import org.elasticsearch.rest.action.search.RestSearchScrollAction;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+
+public class KibanaPlugin extends Plugin implements SystemIndexPlugin {
+
+    public static final Setting<List<String>> KIBANA_INDEX_NAMES_SETTING = Setting.listSetting(
+        "kibana.system_indices",
+        Collections.unmodifiableList(Arrays.asList(".kibana*", ".reporting")),
+        Function.identity(),
+        Property.NodeScope
+    );
+
+    @Override
+    public Collection<SystemIndexDescriptor> getSystemIndexDescriptors(Settings settings) {
+        return Collections.unmodifiableList(
+            KIBANA_INDEX_NAMES_SETTING.get(settings)
+                .stream()
+                .map(pattern -> new SystemIndexDescriptor(pattern, "System index used by kibana"))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @Override
+    public List<RestHandler> getRestHandlers(
+        Settings settings,
+        RestController restController,
+        ClusterSettings clusterSettings,
+        IndexScopedSettings indexScopedSettings,
+        SettingsFilter settingsFilter,
+        IndexNameExpressionResolver indexNameExpressionResolver,
+        Supplier<DiscoveryNodes> nodesInCluster
+    ) {
+        // TODO need to figure out what subset of system indices Kibana should have access to via these APIs
+        return Collections.unmodifiableList(
+            Arrays.asList(
+                // Based on https://github.com/elastic/kibana/issues/49764
+                // apis needed to perform migrations... ideally these will go away
+                new KibanaWrappedRestHandler(new RestCreateIndexAction()),
+                new KibanaWrappedRestHandler(new RestGetAliasesAction()),
+                new KibanaWrappedRestHandler(new RestIndexPutAliasAction()),
+                new KibanaWrappedRestHandler(new RestRefreshAction()),
+
+                // apis needed to access saved objects
+                new KibanaWrappedRestHandler(new RestGetAction()),
+                new KibanaWrappedRestHandler(new RestMultiGetAction(settings)),
+                new KibanaWrappedRestHandler(new RestSearchAction()),
+                new KibanaWrappedRestHandler(new RestBulkAction(settings)),
+                new KibanaWrappedRestHandler(new RestDeleteAction()),
+                new KibanaWrappedRestHandler(new RestDeleteByQueryAction()),
+
+                // api used for testing
+                new KibanaWrappedRestHandler(new RestUpdateSettingsAction()),
+
+                // apis used specifically by reporting
+                new KibanaWrappedRestHandler(new RestGetIndicesAction()),
+                new KibanaWrappedRestHandler(new RestIndexAction()),
+                new KibanaWrappedRestHandler(new CreateHandler()),
+                new KibanaWrappedRestHandler(new AutoIdHandler(nodesInCluster)),
+                new KibanaWrappedRestHandler(new RestUpdateAction()),
+                new KibanaWrappedRestHandler(new RestSearchScrollAction()),
+                new KibanaWrappedRestHandler(new RestClearScrollAction())
+            )
+        );
+
+    }
+
+    @Override
+    public List<Setting<?>> getSettings() {
+        return Collections.singletonList(KIBANA_INDEX_NAMES_SETTING);
+    }
+
+    static class KibanaWrappedRestHandler extends BaseRestHandler.Wrapper {
+
+        KibanaWrappedRestHandler(BaseRestHandler delegate) {
+            super(delegate);
+        }
+
+        @Override
+        public String getName() {
+            return "kibana_" + super.getName();
+        }
+
+        @Override
+        public List<Route> routes() {
+            return Collections.unmodifiableList(
+                super.routes().stream()
+                    .map(route -> new Route(route.getMethod(), "/_kibana" + route.getPath()))
+                    .collect(Collectors.toList())
+            );
+        }
+    }
+}

modules/kibana/src/test/java/org/elasticsearch/kibana/KibanaPluginTests.java

@@ -0,0 +1,51 @@
+/*
+ * 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.kibana;
+
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.indices.SystemIndexDescriptor;
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.is;
+
+public class KibanaPluginTests extends ESTestCase {
+
+    public void testKibanaIndexNames() {
+        assertThat(new KibanaPlugin().getSettings(), contains(KibanaPlugin.KIBANA_INDEX_NAMES_SETTING));
+        assertThat(
+            new KibanaPlugin().getSystemIndexDescriptors(Settings.EMPTY)
+                .stream()
+                .map(SystemIndexDescriptor::getIndexPattern)
+                .collect(Collectors.toList()),
+            contains(".kibana*", ".reporting")
+        );
+        final List<String> names = Collections.unmodifiableList(Arrays.asList("." + randomAlphaOfLength(4), "." + randomAlphaOfLength(6)));
+        final List<String> namesFromDescriptors = new KibanaPlugin().getSystemIndexDescriptors(
+            Settings.builder().putList(KibanaPlugin.KIBANA_INDEX_NAMES_SETTING.getKey(), names).build()
+        ).stream().map(SystemIndexDescriptor::getIndexPattern).collect(Collectors.toList());
+        assertThat(namesFromDescriptors, is(names));
+    }
+}