Apply settings filter to get cluster settings API (#33247)

Some settings have filters applied to them and we use this in logs and
the get nodes info API. For consistency, we should apply this in the get
cluster settings API too.

server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestClusterGetSettingsAction.java

@@ -87,13 +87,19 @@ public class RestClusterGetSettingsAction extends BaseRestHandler {
 
     private XContentBuilder renderResponse(ClusterState state, boolean renderDefaults, XContentBuilder builder, ToXContent.Params params)
             throws IOException {
-        return
-            new ClusterGetSettingsResponse(
-                state.metaData().persistentSettings(),
-                state.metaData().transientSettings(),
-                renderDefaults ?
-                    settingsFilter.filter(clusterSettings.diff(state.metaData().settings(), this.settings)) :
-                    Settings.EMPTY
-            ).toXContent(builder, params);
+        return response(state, renderDefaults, settingsFilter, clusterSettings, settings).toXContent(builder, params);
     }
+
+    static ClusterGetSettingsResponse response(
+            final ClusterState state,
+            final boolean renderDefaults,
+            final SettingsFilter settingsFilter,
+            final ClusterSettings clusterSettings,
+            final Settings settings) {
+        return new ClusterGetSettingsResponse(
+                settingsFilter.filter(state.metaData().persistentSettings()),
+                settingsFilter.filter(state.metaData().transientSettings()),
+                renderDefaults ? settingsFilter.filter(clusterSettings.diff(state.metaData().settings(), settings)) : Settings.EMPTY);
+    }
+
 }

server/src/test/java/org/elasticsearch/rest/action/admin/cluster/RestClusterGetSettingsActionTests.java

@@ -0,0 +1,70 @@
+/*
+ * 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.rest.action.admin.cluster;
+
+import org.elasticsearch.action.admin.cluster.settings.ClusterGetSettingsResponse;
+import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.cluster.metadata.MetaData;
+import org.elasticsearch.common.settings.ClusterSettings;
+import org.elasticsearch.common.settings.Setting;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.settings.SettingsFilter;
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.Collections;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+
+public class RestClusterGetSettingsActionTests extends ESTestCase {
+
+    public void testFilterPersistentSettings() {
+        runTestFilterSettingsTest(MetaData.Builder::persistentSettings, ClusterGetSettingsResponse::getPersistentSettings);
+    }
+
+    public void testFilterTransientSettings() {
+        runTestFilterSettingsTest(MetaData.Builder::transientSettings, ClusterGetSettingsResponse::getTransientSettings);
+    }
+
+    private void runTestFilterSettingsTest(
+            final BiConsumer<MetaData.Builder, Settings> md, final Function<ClusterGetSettingsResponse, Settings> s) {
+        final MetaData.Builder mdBuilder = new MetaData.Builder();
+        final Settings settings = Settings.builder().put("foo.filtered", "bar").put("foo.non_filtered", "baz").build();
+        md.accept(mdBuilder, settings);
+        final ClusterState.Builder builder = new ClusterState.Builder(ClusterState.EMPTY_STATE).metaData(mdBuilder);
+        final SettingsFilter filter = new SettingsFilter(Settings.EMPTY, Collections.singleton("foo.filtered"));
+        final Setting.Property[] properties = {Setting.Property.Dynamic, Setting.Property.Filtered, Setting.Property.NodeScope};
+        final Set<Setting<?>> settingsSet = Stream.concat(
+                ClusterSettings.BUILT_IN_CLUSTER_SETTINGS.stream(),
+                Stream.concat(
+                        Stream.of(Setting.simpleString("foo.filtered", properties)),
+                        Stream.of(Setting.simpleString("foo.non_filtered", properties))))
+                .collect(Collectors.toSet());
+        final ClusterSettings clusterSettings = new ClusterSettings(Settings.EMPTY, settingsSet);
+        final ClusterGetSettingsResponse response =
+                RestClusterGetSettingsAction.response(builder.build(), randomBoolean(), filter, clusterSettings, Settings.EMPTY);
+        assertFalse(s.apply(response).hasValue("foo.filtered"));
+        assertTrue(s.apply(response).hasValue("foo.non_filtered"));
+    }
+
+}