Copy and validate soft-deletes setting on resize

server/src/main/java/org/elasticsearch/action/admin/indices/shrink/TransportResizeAction.java

@@ -39,6 +39,7 @@
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.IndexNotFoundException;
+import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.shard.DocsStats;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -171,6 +172,12 @@ static CreateIndexClusterStateUpdateRequest prepareCreateIndexRequest(final Resi
                 throw new IllegalArgumentException("cannot provide index.number_of_routing_shards on resize");
             }
         }
+        if (IndexSettings.INDEX_SOFT_DELETES_SETTING.exists(metaData.getSettings()) &&
+            IndexSettings.INDEX_SOFT_DELETES_SETTING.get(metaData.getSettings()) &&
+            IndexSettings.INDEX_SOFT_DELETES_SETTING.exists(targetIndexSettings) &&
+            IndexSettings.INDEX_SOFT_DELETES_SETTING.get(targetIndexSettings) == false) {
+            throw new IllegalArgumentException("Can't disable [index.soft_deletes.enabled] setting on resize");
+        }
         String cause = resizeRequest.getResizeType().name().toLowerCase(Locale.ROOT) + "_index";
         targetIndex.cause(cause);
         Settings.Builder settingsBuilder = Settings.builder().put(targetIndexSettings);

server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexService.java

@@ -749,7 +749,8 @@ static void prepareResizeIndexSettings(
             }
         } else {
             final Predicate<String> sourceSettingsPredicate =
-                    (s) -> (s.startsWith("index.similarity.") || s.startsWith("index.analysis.") || s.startsWith("index.sort."))
+                    (s) -> (s.startsWith("index.similarity.") || s.startsWith("index.analysis.") ||
+                            s.startsWith("index.sort.") || s.equals("index.soft_deletes.enabled"))
                             && indexSettingsBuilder.keys().contains(s) == false;
             builder.put(sourceMetaData.getSettings().filter(sourceSettingsPredicate));
         }

server/src/test/java/org/elasticsearch/action/admin/indices/shrink/TransportResizeActionTests.java

@@ -47,6 +47,7 @@
 import java.util.HashSet;
 
 import static java.util.Collections.emptyMap;
+import static org.hamcrest.Matchers.equalTo;
 
 public class TransportResizeActionTests extends ESTestCase {
 
@@ -92,6 +93,16 @@ public void testErrorCondition() {
             ).getMessage().startsWith("Can't merge index with more than [2147483519] docs - too many documents in shards "));
 
 
+        IllegalArgumentException softDeletesError = expectThrows(IllegalArgumentException.class, () -> {
+            ResizeRequest req = new ResizeRequest("target", "source");
+            req.getTargetIndexRequest().settings(Settings.builder().put("index.soft_deletes.enabled", false));
+            ClusterState clusterState = createClusterState("source", 8, 1,
+                Settings.builder().put("index.blocks.write", true).put("index.soft_deletes.enabled", true).build());
+            TransportResizeAction.prepareCreateIndexRequest(req, clusterState,
+                (i) -> new DocsStats(between(10, 1000), between(1, 10), between(1, 10000)), "source", "target");
+        });
+        assertThat(softDeletesError.getMessage(), equalTo("Can't disable [index.soft_deletes.enabled] setting on resize"));
+
         // create one that won't fail
         ClusterState clusterState = ClusterState.builder(createClusterState("source", randomIntBetween(2, 10), 0,
             Settings.builder().put("index.blocks.write", true).build())).nodes(DiscoveryNodes.builder().add(newNode("node1")))

server/src/test/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexServiceTests.java

@@ -261,6 +261,7 @@ public void testPrepareResizeIndexSettings() {
                         .put("index.version.upgraded", upgraded)
                         .put("index.similarity.default.type", "BM25")
                         .put("index.analysis.analyzer.default.tokenizer", "keyword")
+                        .put("index.soft_deletes.enabled", "true")
                         .build();
         runPrepareResizeIndexSettingsTest(
                 indexSettings,
@@ -277,6 +278,7 @@ public void testPrepareResizeIndexSettings() {
                     assertThat(settings.get("index.allocation.max_retries"), equalTo("1"));
                     assertThat(settings.getAsVersion("index.version.created", null), equalTo(version));
                     assertThat(settings.getAsVersion("index.version.upgraded", null), equalTo(upgraded));
+                    assertThat(settings.get("index.soft_deletes.enabled"), equalTo("true"));
                 });
     }
 
@@ -337,6 +339,15 @@ public void testPrepareResizeIndexSettingsSimilaritySettings() {
 
     }
 
+    public void testDoNotOverrideSoftDeletesSettingOnResize() {
+        runPrepareResizeIndexSettingsTest(
+            Settings.builder().put("index.soft_deletes.enabled", "false").build(),
+            Settings.builder().put("index.soft_deletes.enabled", "true").build(),
+            Collections.emptyList(),
+            randomBoolean(),
+            settings -> assertThat(settings.get("index.soft_deletes.enabled"), equalTo("true")));
+    }
+
     private void runPrepareResizeIndexSettingsTest(
             final Settings sourceSettings,
             final Settings requestSettings,