ESQL: Make settings dynamic (#101516) (#101761)

* Return QUERY_RESULT_TRUNCATION_DEFAULT_SIZE in EsqlPlugin::getSettings.
* Make ESQL settings Dynamic.

Author: alex-spies

docs/changelog/101516.yaml

@@ -0,0 +1,5 @@
+pr: 101516
+summary: "Make settings dynamic"
+area: ES|QL
+type: enhancement
+issues: []

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlActionIT.java

@@ -8,12 +8,15 @@
 package org.elasticsearch.xpack.esql.action;
 
 import org.elasticsearch.Build;
+import org.elasticsearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
 import org.elasticsearch.action.bulk.BulkRequestBuilder;
 import org.elasticsearch.action.index.IndexRequest;
 import org.elasticsearch.action.index.IndexRequestBuilder;
 import org.elasticsearch.action.support.WriteRequest;
+import org.elasticsearch.client.internal.ClusterAdminClient;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
+import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.IndexService;
@@ -27,6 +30,7 @@
 import org.elasticsearch.xcontent.json.JsonXContent;
 import org.elasticsearch.xpack.esql.analysis.VerificationException;
 import org.elasticsearch.xpack.esql.expression.function.EsqlFunctionRegistry;
+import org.elasticsearch.xpack.esql.plugin.EsqlPlugin;
 import org.junit.Before;
 
 import java.io.IOException;
@@ -69,7 +73,6 @@
 import static org.hamcrest.Matchers.nullValue;
 
 public class EsqlActionIT extends AbstractEsqlIntegTestCase {
-
     long epoch = System.currentTimeMillis();
 
     @Before
@@ -1459,4 +1462,47 @@ private void createAndPopulateIndex(String indexName, Settings additionalSetting
         }
         ensureYellow(indexName);
     }
+
+    public void testDefaultTruncationSizeSetting() {
+        ClusterAdminClient client = admin().cluster();
+
+        Settings settings = Settings.builder().put(EsqlPlugin.QUERY_RESULT_TRUNCATION_DEFAULT_SIZE.getKey(), 1).build();
+
+        ClusterUpdateSettingsRequest settingsRequest = new ClusterUpdateSettingsRequest().persistentSettings(settings);
+
+        client.updateSettings(settingsRequest).actionGet();
+        try (EsqlQueryResponse results = run("from test")) {
+            logger.info(results);
+            assertEquals(1, getValuesList(results).size());
+        } finally {
+            clearPersistentSettings(EsqlPlugin.QUERY_RESULT_TRUNCATION_DEFAULT_SIZE);
+        }
+    }
+
+    public void testMaxTruncationSizeSetting() {
+        ClusterAdminClient client = admin().cluster();
+
+        Settings settings = Settings.builder().put(EsqlPlugin.QUERY_RESULT_TRUNCATION_MAX_SIZE.getKey(), 10).build();
+
+        ClusterUpdateSettingsRequest settingsRequest = new ClusterUpdateSettingsRequest().persistentSettings(settings);
+
+        client.updateSettings(settingsRequest).actionGet();
+        try (EsqlQueryResponse results = run("from test | limit 40")) {
+            logger.info(results);
+            assertEquals(10, getValuesList(results).size());
+        } finally {
+            clearPersistentSettings(EsqlPlugin.QUERY_RESULT_TRUNCATION_MAX_SIZE);
+        }
+    }
+
+    private void clearPersistentSettings(Setting<?>... settings) {
+        Settings.Builder clearedSettings = Settings.builder();
+
+        for (Setting<?> s : settings) {
+            clearedSettings.putNull(s.getKey());
+        }
+
+        var clearSettingsRequest = new ClusterUpdateSettingsRequest().persistentSettings(clearedSettings.build());
+        admin().cluster().updateSettings(clearSettingsRequest).actionGet();
+    }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/EsqlPlugin.java

@@ -76,15 +76,17 @@ public class EsqlPlugin extends Plugin implements ActionPlugin {
         10000,
         1,
         1000000,
-        Setting.Property.NodeScope
+        Setting.Property.NodeScope,
+        Setting.Property.Dynamic
     );
 
     public static final Setting<Integer> QUERY_RESULT_TRUNCATION_DEFAULT_SIZE = Setting.intSetting(
         "esql.query.result_truncation_default_size",
         500,
         1,
         10000,
-        Setting.Property.NodeScope
+        Setting.Property.NodeScope,
+        Setting.Property.Dynamic
     );
 
     @Override
@@ -121,7 +123,7 @@ public Collection<Object> createComponents(
      */
     @Override
     public List<Setting<?>> getSettings() {
-        return List.of(QUERY_RESULT_TRUNCATION_MAX_SIZE);
+        return List.of(QUERY_RESULT_TRUNCATION_DEFAULT_SIZE, QUERY_RESULT_TRUNCATION_MAX_SIZE);
     }
 
     @Override

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/TransportEsqlQueryAction.java

@@ -13,7 +13,6 @@
 import org.elasticsearch.action.support.HandledTransportAction;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.inject.Inject;
-import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.concurrent.EsExecutors;
 import org.elasticsearch.compute.data.BlockFactory;
@@ -48,11 +47,9 @@ public class TransportEsqlQueryAction extends HandledTransportAction<EsqlQueryRe
     private final Executor requestExecutor;
     private final EnrichPolicyResolver enrichPolicyResolver;
     private final EnrichLookupService enrichLookupService;
-    private final Settings settings;
 
     @Inject
     public TransportEsqlQueryAction(
-        Settings settings,
         TransportService transportService,
         ActionFilters actionFilters,
         PlanExecutor planExecutor,
@@ -81,7 +78,6 @@ public TransportEsqlQueryAction(
             bigArrays,
             blockFactory
         );
-        this.settings = settings;
     }
 
     @Override
@@ -98,8 +94,8 @@ private void doExecuteForked(Task task, EsqlQueryRequest request, ActionListener
             null,
             clusterService.getClusterName().value(),
             request.pragmas(),
-            EsqlPlugin.QUERY_RESULT_TRUNCATION_MAX_SIZE.get(settings),
-            EsqlPlugin.QUERY_RESULT_TRUNCATION_DEFAULT_SIZE.get(settings),
+            clusterService.getClusterSettings().get(EsqlPlugin.QUERY_RESULT_TRUNCATION_MAX_SIZE),
+            clusterService.getClusterSettings().get(EsqlPlugin.QUERY_RESULT_TRUNCATION_DEFAULT_SIZE),
             request.query()
         );
         String sessionId = sessionID(task);