Reject setting index.optimize_auto_generated_id after version 7.0.0

server/src/main/java/org/elasticsearch/indices/IndicesService.java

@@ -83,6 +83,7 @@
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.cache.request.ShardRequestCache;
 import org.elasticsearch.index.engine.CommitStats;
+import org.elasticsearch.index.engine.EngineConfig;
 import org.elasticsearch.index.engine.EngineFactory;
 import org.elasticsearch.index.engine.InternalEngineFactory;
 import org.elasticsearch.index.fielddata.IndexFieldDataCache;
@@ -493,6 +494,11 @@ private synchronized IndexService createIndexService(final String reason,
                                                          List<IndexEventListener> builtInListeners,
                                                          IndexingOperationListener... indexingOperationListeners) throws IOException {
         final IndexSettings idxSettings = new IndexSettings(indexMetaData, settings, indexScopedSettings);
+        if (idxSettings.getIndexVersionCreated().onOrAfter(Version.V_7_0_0)
+            && EngineConfig.INDEX_OPTIMIZE_AUTO_GENERATED_IDS.exists(idxSettings.getSettings())) {
+            throw new IllegalArgumentException(
+                "Setting [" + EngineConfig.INDEX_OPTIMIZE_AUTO_GENERATED_IDS.getKey() + "] was removed in version 7.0.0");
+        }
         // we ignore private settings since they are not registered settings
         indexScopedSettings.validate(indexMetaData.getSettings(), true, true, true);
         logger.debug("creating Index [{}], shards [{}]/[{}] - reason [{}]",

server/src/test/java/org/elasticsearch/indices/IndicesServiceTests.java

@@ -642,5 +642,48 @@ public static ClusterState createClusterForShardLimitTest(int nodesInCluster, in
             .build();
     }
 
+    public void testOptimizeAutoGeneratedIdsSettingRemoval() throws Exception {
+        final IndicesService indicesService = getIndicesService();
+
+        final Index index = new Index("foo-index", UUIDs.randomBase64UUID());
+        Settings.Builder builder = Settings.builder()
+            .put(IndexMetaData.SETTING_VERSION_CREATED, Version.V_7_0_0)
+            .put(IndexMetaData.SETTING_INDEX_UUID, index.getUUID());
+        IndexMetaData indexMetaData = new IndexMetaData.Builder(index.getName())
+            .settings(builder.build())
+            .numberOfShards(1)
+            .numberOfReplicas(0)
+            .build();
+        IndexService indexService = indicesService.createIndex(indexMetaData, Collections.emptyList());
+        assertNotNull(indexService);
+
+        final Index index2 = new Index("bar-index", UUIDs.randomBase64UUID());
+        Settings.Builder builder2 = Settings.builder()
+            .put(IndexMetaData.SETTING_VERSION_CREATED, Version.V_7_0_0)
+            .put(IndexMetaData.SETTING_INDEX_UUID, index2.getUUID())
+            .put(EngineConfig.INDEX_OPTIMIZE_AUTO_GENERATED_IDS.getKey(), randomBoolean());
+        IndexMetaData indexMetaData2 = new IndexMetaData.Builder(index2.getName())
+            .settings(builder2.build())
+            .numberOfShards(1)
+            .numberOfReplicas(0)
+            .build();
+        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class,
+            () -> indicesService.createIndex(indexMetaData2, Collections.emptyList()));
+        assertEquals("Setting [" + EngineConfig.INDEX_OPTIMIZE_AUTO_GENERATED_IDS.getKey() + "] was removed in version 7.0.0",
+            ex.getMessage());
+
+        Version version = randomFrom(Version.V_6_0_0_rc1, Version.V_6_0_0, Version.V_6_2_0, Version.V_6_3_0, Version.V_6_4_0);
+        builder = Settings.builder()
+            .put(IndexMetaData.SETTING_VERSION_CREATED, version)
+            .put(IndexMetaData.SETTING_INDEX_UUID, index2.getUUID())
+            .put(EngineConfig.INDEX_OPTIMIZE_AUTO_GENERATED_IDS.getKey(), randomBoolean());
+        IndexMetaData indexMetaData3 = new IndexMetaData.Builder(index2.getName())
+            .settings(builder.build())
+            .numberOfShards(1)
+            .numberOfReplicas(0)
+            .build();
+        IndexService indexService2 = indicesService.createIndex(indexMetaData3, Collections.emptyList());
+        assertNotNull(indexService2);
+    }
 
 }