Re-introduce index.mapper.dynamic setting (#120484)

This change re-introduces the deprecated index.mapper.dynamic setting that
was already removed via #113000. With the new read-only support for N-2 indices
we can still have this setting in indices created with version 7, so it's better to have
the deprecated settings definition around.

Author: cbuescher

server/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java

@@ -163,6 +163,7 @@ public final class IndexScopedSettings extends AbstractScopedSettings {
         MapperService.INDEX_MAPPING_DEPTH_LIMIT_SETTING,
         MapperService.INDEX_MAPPING_DIMENSION_FIELDS_LIMIT_SETTING,
         MapperService.INDEX_MAPPING_FIELD_NAME_LENGTH_LIMIT_SETTING,
+        MapperService.INDEX_MAPPER_DYNAMIC_SETTING,
         BitsetFilterCache.INDEX_LOAD_RANDOM_ACCESS_FILTERS_EAGERLY_SETTING,
         IndexModule.INDEX_STORE_TYPE_SETTING,
         IndexModule.INDEX_STORE_PRE_LOAD_SETTING,

server/src/main/java/org/elasticsearch/common/settings/Setting.java

@@ -151,7 +151,8 @@ public enum Property {
          * Indicates that this index-level setting was deprecated in {@link Version#V_7_17_0} and is
          * forbidden in indices created from {@link Version#V_8_0_0} onwards.
          */
-        @UpdateForV9(owner = UpdateForV9.Owner.CORE_INFRA) // introduce IndexSettingDeprecatedInV8AndRemovedInV9 to replace this constant
+        @UpdateForV9(owner = UpdateForV9.Owner.CORE_INFRA) // introduce IndexSettingDeprecatedInV8AndRemovedInV10
+        // note we still need v7 settings in v9 because we support reading from N-2 indices now
         IndexSettingDeprecatedInV7AndRemovedInV8,
 
         /**

server/src/main/java/org/elasticsearch/index/mapper/MapperService.java

@@ -164,6 +164,17 @@ public boolean isAutoUpdate() {
         Property.Dynamic,
         Property.IndexScope
     );
+    /**
+     * Legacy index setting, kept for 7.x BWC compatibility. This setting has no effect in 8.x. Do not use.
+     */
+    @Deprecated
+    public static final Setting<Boolean> INDEX_MAPPER_DYNAMIC_SETTING = Setting.boolSetting(
+        "index.mapper.dynamic",
+        true,
+        Property.Dynamic,
+        Property.IndexScope,
+        Property.IndexSettingDeprecatedInV7AndRemovedInV8
+    );
 
     private final IndexAnalyzers indexAnalyzers;
     private final MappingParser mappingParser;

server/src/test/java/org/elasticsearch/index/IndexSettingsTests.java

@@ -10,14 +10,18 @@
 package org.elasticsearch.index;
 
 import org.elasticsearch.cluster.metadata.IndexMetadata;
+import org.elasticsearch.cluster.metadata.IndexMetadataVerifier;
 import org.elasticsearch.common.settings.AbstractScopedSettings;
 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.unit.ByteSizeValue;
 import org.elasticsearch.core.TimeValue;
+import org.elasticsearch.index.mapper.MapperMetrics;
+import org.elasticsearch.index.mapper.MapperRegistry;
 import org.elasticsearch.index.translog.Translog;
+import org.elasticsearch.plugins.MapperPlugin;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.index.IndexVersionUtils;
 import org.hamcrest.Matchers;
@@ -39,6 +43,7 @@
 import static org.elasticsearch.index.IndexSettings.STATELESS_MIN_NON_FAST_REFRESH_INTERVAL;
 import static org.elasticsearch.index.IndexSettings.TIME_SERIES_END_TIME;
 import static org.elasticsearch.index.IndexSettings.TIME_SERIES_START_TIME;
+import static org.elasticsearch.index.mapper.MapperService.INDEX_MAPPER_DYNAMIC_SETTING;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.core.StringContains.containsString;
@@ -839,6 +844,35 @@ public void testTimeSeriesTimeBoundary() {
         assertThat(e.getMessage(), Matchers.containsString("index.time_series.end_time must be larger than index.time_series.start_time"));
     }
 
+    public void testIndexMapperDynamic() {
+        Settings settings = Settings.builder().put(INDEX_MAPPER_DYNAMIC_SETTING.getKey(), randomBoolean()).build();
+
+        INDEX_MAPPER_DYNAMIC_SETTING.get(settings);
+        assertWarnings(
+            "[index.mapper.dynamic] setting was deprecated in the previous Elasticsearch release and is removed in this release."
+        );
+
+        IndexMetadata idxMetaData = newIndexMeta("test", settings);
+        IndexMetadataVerifier indexMetadataVerifier = new IndexMetadataVerifier(
+            Settings.EMPTY,
+            null,
+            xContentRegistry(),
+            new MapperRegistry(Collections.emptyMap(), Collections.emptyMap(), Collections.emptyMap(), MapperPlugin.NOOP_FIELD_FILTER),
+            IndexScopedSettings.DEFAULT_SCOPED_SETTINGS,
+            null,
+            MapperMetrics.NOOP
+        );
+        IndexMetadata verifiedMetaData = indexMetadataVerifier.verifyIndexMetadata(
+            idxMetaData,
+            IndexVersions.MINIMUM_COMPATIBLE,
+            IndexVersions.MINIMUM_READONLY_COMPATIBLE
+        );
+        assertEquals(idxMetaData, verifiedMetaData);
+        assertWarnings(
+            "[index.mapper.dynamic] setting was deprecated in the previous Elasticsearch release and is removed in this release."
+        );
+    }
+
     public void testSame() {
         final var indexSettingKey = "index.example.setting";
         final var archivedSettingKey = "archived.example.setting";