HSEARCH-4435 Custom Elasticsearch settings/mapping require the backend to be started

backend/elasticsearch/src/main/java/org/hibernate/search/backend/elasticsearch/impl/ElasticsearchBackendImpl.java

@@ -94,6 +94,7 @@ class ElasticsearchBackendImpl implements BackendImplementor,
 	private final ElasticsearchSimpleWorkOrchestrator generalPurposeOrchestrator;
 
 	private final ElasticsearchIndexFieldTypeFactoryProvider typeFactoryProvider;
+	private final Gson userFacingGson;
 	private final MultiTenancyStrategy multiTenancyStrategy;
 	private final BeanHolder<? extends IndexLayoutStrategy> indexLayoutStrategyHolder;
 	private final TypeNameMapping typeNameMapping;
@@ -120,6 +121,7 @@ class ElasticsearchBackendImpl implements BackendImplementor,
 		);
 		this.multiTenancyStrategy = multiTenancyStrategy;
 		this.typeFactoryProvider = typeFactoryProvider;
+		this.userFacingGson = userFacingGson;
 		this.indexLayoutStrategyHolder = indexLayoutStrategyHolder;
 		this.typeNameMapping = typeNameMapping;
 
@@ -304,7 +306,7 @@ private IndexSettings customIndexSettings(BackendBuildContext buildContext,
 				throw log.customIndexSettingsFileNotFound( filePath, indexEventContext );
 			}
 			try ( Reader reader = new InputStreamReader( inputStream, StandardCharsets.UTF_8 ) ) {
-				return link.getGsonProvider().getGson().fromJson( reader, IndexSettings.class );
+				return userFacingGson.fromJson( reader, IndexSettings.class );
 			}
 		}
 		catch (IOException e) {
@@ -329,7 +331,7 @@ private RootTypeMapping customIndexMappings(BackendBuildContext buildContext,
 				throw log.customIndexMappingFileNotFound( filePath, indexEventContext );
 			}
 			try ( Reader reader = new InputStreamReader( inputStream, StandardCharsets.UTF_8 ) ) {
-				return link.getGsonProvider().getGson().fromJson( reader, RootTypeMapping.class );
+				return userFacingGson.fromJson( reader, RootTypeMapping.class );
 			}
 		}
 		catch (IOException e) {

backend/elasticsearch/src/main/java/org/hibernate/search/backend/elasticsearch/impl/ElasticsearchLinkImpl.java

@@ -161,7 +161,7 @@ void onStop() {
 	private void checkStarted() {
 		if ( clientImplementor == null ) {
 			throw new AssertionFailure(
-					"Attempt to retrieve Elasticsearch client or related information before the backend was started."
+					"Attempt to retrieve Elasticsearch client or related information before the Elasticsearch client was started."
 			);
 		}
 	}

integrationtest/backend/elasticsearch/src/test/java/org/hibernate/search/integrationtest/backend/elasticsearch/bootstrap/ElasticsearchBootstrapIT.java

@@ -9,12 +9,14 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.hibernate.search.util.impl.integrationtest.common.assertion.SearchResultAssert.assertThatQuery;
+import static org.hibernate.search.util.impl.test.JsonHelper.assertJsonEqualsIgnoringUnknownFields;
 
 import java.util.HashMap;
 import java.util.Map;
 
 import org.hibernate.search.backend.elasticsearch.ElasticsearchVersion;
 import org.hibernate.search.backend.elasticsearch.cfg.ElasticsearchBackendSettings;
+import org.hibernate.search.backend.elasticsearch.cfg.ElasticsearchIndexSettings;
 import org.hibernate.search.backend.elasticsearch.cfg.spi.ElasticsearchBackendSpiSettings;
 import org.hibernate.search.backend.elasticsearch.client.spi.ElasticsearchRequest;
 import org.hibernate.search.engine.cfg.BackendSettings;
@@ -25,6 +27,7 @@
 import org.hibernate.search.integrationtest.backend.tck.testsupport.util.rule.SearchSetupHelper;
 import org.hibernate.search.util.common.SearchException;
 import org.hibernate.search.util.impl.integrationtest.backend.elasticsearch.dialect.ElasticsearchTestDialect;
+import org.hibernate.search.util.impl.integrationtest.backend.elasticsearch.rule.TestElasticsearchClient;
 import org.hibernate.search.util.impl.integrationtest.common.FailureReportUtils;
 import org.hibernate.search.util.impl.integrationtest.mapper.stub.StubMappedIndex;
 import org.hibernate.search.util.impl.integrationtest.mapper.stub.StubMappingSchemaManagementStrategy;
@@ -42,6 +45,9 @@ public class ElasticsearchBootstrapIT {
 	@Rule
 	public ElasticsearchClientSpy elasticsearchClientSpy = new ElasticsearchClientSpy();
 
+	@Rule
+	public TestElasticsearchClient elasticsearchClient = new TestElasticsearchClient();
+
 	private final StubMappedIndex index = StubMappedIndex.withoutFields();
 
 	/**
@@ -270,6 +276,49 @@ public void noVersionCheck_versionOverrideOnStart_compatibleVersion() {
 		assertThat( elasticsearchClientSpy.getRequestCount() ).isNotZero();
 	}
 
+	/**
+	 * Check custom settings/mapping can be parsed when version_check.enabled is false,
+	 * meaning the elasticsearch link is only established *after*
+	 * the custom settings/mapping are parsed.
+	 */
+	@Test
+	@TestForIssue(jiraKey = {"HSEARCH-4435"})
+	public void noVersionCheck_customSettingsAndMapping() {
+		ElasticsearchVersion actualVersion = ElasticsearchTestDialect.getActualVersion();
+		String versionWithMajorAndMinorOnly = actualVersion.distribution() + ":"
+				+ actualVersion.major() + "." + actualVersion.minor().getAsInt();
+
+		SearchSetupHelper.PartialSetup partialSetup = setupHelper.start()
+				.withBackendProperty( ElasticsearchBackendSettings.VERSION, versionWithMajorAndMinorOnly )
+				.withBackendProperty( ElasticsearchBackendSpiSettings.CLIENT_FACTORY,
+						elasticsearchClientSpy.factoryReference() )
+				.withBackendProperty( ElasticsearchIndexSettings.SCHEMA_MANAGEMENT_SETTINGS_FILE,
+						"bootstrap-it/custom-settings.json" )
+				.withBackendProperty( ElasticsearchIndexSettings.SCHEMA_MANAGEMENT_MAPPING_FILE,
+						"bootstrap-it/custom-mapping.json" )
+				.withSchemaManagement( StubMappingSchemaManagementStrategy.DROP_ON_SHUTDOWN_ONLY )
+				.withIndex( index )
+				.setupFirstPhaseOnly();
+		// We do not expect the client to be created in the first phase
+		assertThat( elasticsearchClientSpy.getCreatedClientCount() ).isZero();
+
+		Map<String, Object> runtimeProperties = new HashMap<>();
+		runtimeProperties.put( BackendSettings.backendKey( ElasticsearchBackendSettings.VERSION_CHECK_ENABLED ), false );
+		partialSetup.doSecondPhase( AllAwareConfigurationPropertySource.fromMap( runtimeProperties ) );
+		checkBackendWorks();
+
+		assertThat( elasticsearchClient.index( index.name() ).settings( "index.number_of_replicas" ).get() )
+				.isEqualTo( "\"42\"" );
+		assertJsonEqualsIgnoringUnknownFields(
+				"{"
+					+ "'properties': {"
+							+ "'custom': {"
+							+ "}"
+					+ "}"
+				+ "}",
+				elasticsearchClient.index( index.name() ).type().getMapping() );
+	}
+
 	private void checkBackendWorks() {
 		index.schemaManager().createIfMissing().join();
 		assertThatQuery( index.query().where( f -> f.matchAll() ) ).hasNoHits();

integrationtest/backend/elasticsearch/src/test/resources/bootstrap-it/custom-mapping.json

@@ -0,0 +1,7 @@
+{
+  "properties":{
+    "custom":{
+      "type":"keyword"
+    }
+  }
+}

integrationtest/backend/elasticsearch/src/test/resources/bootstrap-it/custom-settings.json

@@ -0,0 +1,3 @@
+{
+  "number_of_replicas": "42"
+}