Hibernate Search: Add configuration property to skip the Elasticsearch version check

docs/src/main/asciidoc/hibernate-search-orm-elasticsearch.adoc

@@ -707,7 +707,7 @@ Entities are attached to a persistence unit by
 link:hibernate-orm#multiple-persistence-units-attaching-model-classes[configuring the Hibernate ORM extension].
 
 [[multiple-persistence-units-attaching-cdi]]
-=== CDI integration
+== CDI integration
 
 You can inject Hibernate Search's main entry points, `SearchSession` and `SearchMapping`, using CDI:
 
@@ -762,6 +762,35 @@ We also inject some data and execute the mass indexer.
 In a real life application, it is obviously something you won't do at startup.
 ====
 
+[[offline-startup]]
+== Offline startup
+
+By default, Hibernate Search sends a few requests to the Elasticsearch cluster on startup.
+If the Elasticsearch cluster is not necessarily up and running when Hibernate Search starts,
+this could cause a startup failure.
+
+To address this, you can configure Hibernate Search to not send any request on startup:
+
+* Disable Elasticsearch version checks on startup by setting the configuration property
+  link:#quarkus-hibernate-search-orm-elasticsearch_quarkus.hibernate-search-orm.elasticsearch.version-check.enabled[`quarkus.hibernate-search-orm.elasticsearch.version-check.enabled`]
+  to `false`.
+* Disable schema management on startup by setting the configuration property
+  link:#quarkus-hibernate-search-orm-elasticsearch_quarkus.hibernate-search-orm.schema-management.strategy[`quarkus.hibernate-search-orm.schema-management.strategy`]
+  to `none`.
+
+Of course, even with this configuration, Hibernate Search still won't be able to index anything or run search queries
+until the Elasticsearch cluster becomes accessible.
+
+[IMPORTANT]
+====
+If you disable automatic schema creation by setting `quarkus.hibernate-search-orm.schema-management.strategy` to `none`,
+you will have to create the schema manually at some point before your application starts persisting/updating entities
+and executing search requests.
+
+See link:{hibernate-search-doc-prefix}#mapper-orm-schema-management-manager[this section of the reference documentation]
+for more information.
+====
+
 == Further reading
 
 If you are interested in learning more about Hibernate Search 6,

extensions/hibernate-search-orm-elasticsearch/deployment/src/test/java/io/quarkus/hibernate/search/elasticsearch/test/offline/IndexedEntity.java

@@ -0,0 +1,17 @@
+package io.quarkus.hibernate.search.elasticsearch.test.offline;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+import org.hibernate.search.mapper.pojo.mapping.definition.annotation.Indexed;
+
+@Entity
+@Indexed
+public class IndexedEntity {
+
+    @Id
+    @GeneratedValue
+    public Long id;
+
+}

extensions/hibernate-search-orm-elasticsearch/deployment/src/test/java/io/quarkus/hibernate/search/elasticsearch/test/offline/StartOfflineTest.java

@@ -0,0 +1,63 @@
+package io.quarkus.hibernate.search.elasticsearch.test.offline;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import javax.inject.Inject;
+import javax.transaction.Transactional;
+
+import org.hibernate.search.mapper.orm.entity.SearchIndexedEntity;
+import org.hibernate.search.mapper.orm.mapping.SearchMapping;
+import org.hibernate.search.mapper.orm.session.SearchSession;
+import org.hibernate.search.util.common.SearchException;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+
+/**
+ * Test that an application can be configured to start successfully
+ * even if the Elasticsearch cluster is offline when the application starts.
+ */
+public class StartOfflineTest {
+
+    @RegisterExtension
+    static QuarkusUnitTest runner = new QuarkusUnitTest()
+            .setArchiveProducer(() -> ShrinkWrap.create(JavaArchive.class)
+                    .addClass(IndexedEntity.class)
+                    .addAsResource("application-start-offline.properties", "application.properties"));
+
+    @Inject
+    SearchMapping searchMapping;
+
+    @Inject
+    SearchSession searchSession;
+
+    @Test
+    public void testHibernateSearchStarted() {
+        assertThat(searchMapping.allIndexedEntities())
+                .hasSize(1)
+                .element(0)
+                .returns(IndexedEntity.class, SearchIndexedEntity::javaClass);
+    }
+
+    @Test
+    @Transactional
+    public void testSchemaManagementAvailableButFailsSinceElasticsearchNotStarted() {
+        assertThatThrownBy(() -> searchSession.schemaManager(IndexedEntity.class).createIfMissing())
+                .isInstanceOf(SearchException.class)
+                .hasMessageContaining("Elasticsearch request failed: Connection refused");
+    }
+
+    @Test
+    @Transactional
+    public void testSearchAvailableButFailsSinceElasticsearchNotStarted() {
+        assertThatThrownBy(() -> searchSession.search(IndexedEntity.class)
+                .where(f -> f.matchAll()).fetchHits(20))
+                        .isInstanceOf(SearchException.class)
+                        .hasMessageContaining("Elasticsearch request failed: Connection refused");
+    }
+
+}

extensions/hibernate-search-orm-elasticsearch/deployment/src/test/resources/application-start-offline.properties

@@ -0,0 +1,11 @@
+quarkus.datasource.db-kind=h2
+quarkus.datasource.jdbc.url=jdbc:h2:mem:default;DB_CLOSE_DELAY=-1
+
+quarkus.hibernate-orm.dialect=org.hibernate.dialect.H2Dialect
+quarkus.hibernate-orm.database.generation=drop-and-create
+
+quarkus.hibernate-search-orm.elasticsearch.version=7.10
+# Simulate an offline Elasticsearch instance by pointing to a non-existing cluster
+quarkus.hibernate-search-orm.elasticsearch.hosts=localhost:14800
+quarkus.hibernate-search-orm.schema-management.strategy=none
+quarkus.hibernate-search-orm.elasticsearch.version-check.enabled=false

extensions/hibernate-search-orm-elasticsearch/runtime/src/main/java/io/quarkus/hibernate/search/orm/elasticsearch/runtime/HibernateSearchElasticsearchBuildTimeConfigPersistenceUnit.java

@@ -67,6 +67,15 @@ public static class ElasticsearchBackendBuildTimeConfig {
         @ConfigItem
         public Optional<ElasticsearchVersion> version;
 
+        // TODO This should be a runtime property, but we need https://hibernate.atlassian.net/browse/HSEARCH-4214 fixed
+        /**
+         * Whether Hibernate Search should check the version of the Elasticsearch cluster on startup.
+         * <p>
+         * Set to {@code false} if the Elasticsearch cluster may not be available on startup.
+         */
+        @ConfigItem(name = "version-check.enabled", defaultValue = "true")
+        public boolean versionCheck;
+
         /**
          * Configuration for the index layout.
          */

extensions/hibernate-search-orm-elasticsearch/runtime/src/main/java/io/quarkus/hibernate/search/orm/elasticsearch/runtime/HibernateSearchElasticsearchRecorder.java

@@ -11,7 +11,6 @@
 
 import javax.enterprise.inject.literal.NamedLiteral;
 
-import org.graalvm.home.Version;
 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.Metadata;
@@ -112,8 +111,6 @@ public void onMetadataInitialized(Metadata metadata, BootstrapContext bootstrapC
     private static final class HibernateSearchIntegrationStaticInitListener
             implements HibernateOrmIntegrationStaticInitListener {
 
-        private static final Version GRAAL_VM_VERSION_21 = Version.create(21);
-
         private final HibernateSearchElasticsearchBuildTimeConfigPersistenceUnit buildTimeConfig;
 
         private HibernateSearchIntegrationStaticInitListener(
@@ -151,6 +148,8 @@ private void contributeBackendBuildTimeProperties(BiConsumer<String, Object> pro
                     ElasticsearchBackendSettings.TYPE_NAME);
             addBackendConfig(propertyCollector, backendName, ElasticsearchBackendSettings.VERSION,
                     elasticsearchBackendConfig.version);
+            addBackendConfig(propertyCollector, backendName, ElasticsearchBackendSettings.VERSION_CHECK_ENABLED,
+                    elasticsearchBackendConfig.versionCheck);
             addBackendConfig(propertyCollector, backendName,
                     ElasticsearchBackendSettings.LAYOUT_STRATEGY,
                     elasticsearchBackendConfig.layout.strategy);

extensions/hibernate-search-orm-elasticsearch/runtime/src/main/java/io/quarkus/hibernate/search/orm/elasticsearch/runtime/HibernateSearchElasticsearchRuntimeConfigPersistenceUnit.java

@@ -327,10 +327,67 @@ public static class SearchQueryLoadingCacheLookupConfig {
     @ConfigGroup
     public static class SchemaManagementConfig {
 
+        // @formatter:off
         /**
-         * The strategy used for index lifecycle.
+         * The schema management strategy, controlling how indexes and their schema
+         * are created, updated, validated or dropped on startup and shutdown.
+         *
+         * Available values:
+         *
+         * [cols=2]
+         * !===
+         * h!Strategy
+         * h!Definition
+         *
+         * !none
+         * !Do nothing: assume that indexes already exist and that their schema matches Hibernate Search's expectations.
+         *
+         * !validate
+         * !Validate that indexes exist and that their schema matches Hibernate Search's expectations.
+         *
+         * If it does not, throw an exception, but make no attempt to fix the problem.
+         *
+         * !create
+         * !For indexes that do not exist, create them along with their schema.
+         *
+         * For indexes that already exist, do nothing: assume that their schema matches Hibernate Search's expectations.
+         *
+         * !create-or-validate (**default**)
+         * !For indexes that do not exist, create them along with their schema.
+         *
+         * For indexes that already exist, validate that their schema matches Hibernate Search's expectations.
+         *
+         * If it does not, throw an exception, but make no attempt to fix the problem.
+         *
+         * !create-or-update
+         * !For indexes that do not exist, create them along with their schema.
+         *
+         * For indexes that already exist, validate that their schema matches Hibernate Search's expectations;
+         * if it does not match expectations, try to update it.
+         *
+         * **This strategy is unfit for production environments**,
+         * due to several important limitations,
+         * but can be useful when developing.
+         *
+         * !drop-and-create
+         * !For indexes that do not exist, create them along with their schema.
+         *
+         * For indexes that already exist, drop them, then create them along with their schema.
+         *
+         * !drop-and-create-and-drop
+         * !For indexes that do not exist, create them along with their schema.
+         *
+         * For indexes that already exist, drop them, then create them along with their schema.
+         *
+         * Also, drop indexes and their schema on shutdown.
+         * !===
+         *
+         * See https://docs.jboss.org/hibernate/stable/search/reference/en-US/html_single/#mapper-orm-schema-management-strategy[this section of the reference documentation]
+         * for more information.
+         *
+         * @asciidoclet
          */
-        // We can't set an actual default value here: see comment on this class.
+        // @formatter:on
         @ConfigItem(defaultValue = "create-or-validate")
         SchemaManagementStrategyName strategy;