Add runtime configuration property quarkus.datasource.active

docs/src/main/asciidoc/cdi.adoc

@@ -253,7 +253,7 @@ Client proxies allow for:
 * Circular dependencies in the dependency graph. Having circular dependencies is often an indication that a redesign should be considered, but sometimes it's inevitable.
 * In rare cases it's practical to destroy the beans manually. A direct injected reference would lead to a stale bean instance.
 
-
+[[ok-you-said-that-there-are-several-kinds-of-beans]]
 == OK. You said that there are several kinds of beans?
 
 Yes. In general, we distinguish:

docs/src/main/asciidoc/config-reference.adoc

@@ -329,6 +329,7 @@ By default, Quarkus provides three profiles, that activate automatically in cert
 * *test* - Activated when running tests
 * *prod* - The default profile when not running in development or test mode
 
+[[custom-profiles]]
 === Custom Profiles
 
 It is also possible to create additional profiles and activate them with the `quarkus.profile` configuration property. A

docs/src/main/asciidoc/datasource.adoc

@@ -405,6 +405,99 @@ AgroalDataSource usersDataSource;
 AgroalDataSource inventoryDataSource;
 ----
 
+[[datasource-active]]
+=== Activate/deactivate datasources
+
+If a datasource is configured at build time,
+by default it is active at runtime,
+that is Quarkus will start the corresponding JDBC connection pool or reactive client on application startup.
+
+To deactivate a datasource at runtime, set `quarkus.datasource[.optional name].active` to `false`.
+Then Quarkus will not start the corresponding JDBC connection pool or reactive client on application startup.
+Any attempt to use the corresponding datasource at runtime will fail with a clear error message.
+
+This is in particular useful when you want an application to be able
+to use one of a pre-determined set of datasources at runtime.
+
+[WARNING]
+====
+If another Quarkus extension relies on an inactive datasource,
+that extension might fail to start.
+
+In such case, you will need to deactivate that other extension too.
+For example see xref:hibernate-orm.adoc#persistence-unit-active[here for Hibernate ORM].
+====
+
+For example, with the following configuration:
+
+[source,properties]
+----
+quarkus.datasource."pg".db-kind=postgres
+quarkus.datasource."pg".active=false
+quarkus.datasource."pg".jdbc.url=jdbc:postgresql:///your_database
+
+quarkus.datasource."oracle".db-kind=oracle
+quarkus.datasource."oracle".active=false
+quarkus.datasource."oracle".jdbc.url=jdbc:oracle:///your_database
+----
+
+Setting `quarkus.datasource."pg".active=true` xref:config-reference.adoc#configuration-sources[at runtime]
+will make only the PostgreSQL datasource available,
+and setting `quarkus.datasource."oracle".active=true` at runtime
+will make only the Oracle datasource available.
+
+[TIP]
+====
+xref:config-reference.adoc#custom-profiles[Custom configuration profiles] can help simplify such a setup.
+By appending the following profile-specific configuration to the one above,
+you can select a persistence unit/datasource at runtime simply by
+xref:config-reference.adoc#multiple-profiles[setting `quarkus.profile`]:
+`quarkus.profile=prod,pg` or `quarkus.profile=prod,oracle`.
+
+[source,properties]
+----
+%pg.quarkus.hibernate-orm."pg".active=true
+%pg.quarkus.datasource."pg".active=true
+# Add any pg-related runtime configuration here, prefixed with "%pg."
+
+%oracle.quarkus.hibernate-orm."oracle".active=true
+%oracle.quarkus.datasource."oracle".active=true
+# Add any pg-related runtime configuration here, prefixed with "%pg."
+----
+====
+
+[TIP]
+====
+It can also be useful to define a xref:cdi.adoc#ok-you-said-that-there-are-several-kinds-of-beans[CDI bean producer] redirecting to the currently active datasource,
+like this:
+
+[source,java,indent=0]
+----
+public class MyProducer {
+    @Inject
+    DataSourceSupport dataSourceSupport;
+
+    @Inject
+    @DataSource("pg")
+    AgroalDataSource pgDataSourceBean;
+
+    @Inject
+    @DataSource("oracle")
+    AgroalDataSource oracleDataSourceBean;
+
+    @Produces
+    @ApplicationScoped
+    public AgroalDataSource dataSource() {
+        if (dataSourceSupport.getInactiveNames().contains("pg")) {
+            return oracleDataSourceBean;
+        } else {
+            return pgDataSourceBean;
+        }
+    }
+}
+----
+====
+
 == Datasource integrations
 
 === Datasource health check

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

@@ -464,6 +464,98 @@ You can inject the `EntityManagerFactory` of a named persistence unit using the
 EntityManagerFactory entityManagerFactory;
 ----
 
+[[persistence-unit-active]]
+=== Activate/deactivate persistence units
+
+If a persistence unit is configured at build time,
+by default it is active at runtime,
+that is Quarkus will start the corresponding Hibernate ORM `SessionFactory` on application startup.
+
+To deactivate a persistence unit at runtime, set `quarkus.hibernate-orm[.optional name].active` to `false`.
+Then Quarkus will not start the corresponding Hibernate ORM `SessionFactory` on application startup.
+Any attempt to use the corresponding persistence unit at runtime will fail with a clear error message.
+
+This is in particular useful when you want an application to be able
+to xref:datasource.adoc#datasource-active[use one of a pre-determined set of datasources at runtime].
+
+For example, with the following configuration:
+
+[source,properties]
+----
+quarkus.hibernate-orm."pg".packages=org.acme.model.shared
+quarkus.hibernate-orm."pg".datasource=pg
+quarkus.hibernate-orm."pg".database.generation=drop-and-create
+quarkus.hibernate-orm."pg".active=false
+quarkus.datasource."pg".db-kind=h2
+quarkus.datasource."pg".active=false
+quarkus.datasource."pg".jdbc.url=jdbc:postgresql:///your_database
+
+quarkus.hibernate-orm."oracle".packages=org.acme.model.shared
+quarkus.hibernate-orm."oracle".datasource=oracle
+quarkus.hibernate-orm."oracle".database.generation=drop-and-create
+quarkus.hibernate-orm."oracle".active=false
+quarkus.datasource."oracle".db-kind=oracle
+quarkus.datasource."oracle".active=false
+quarkus.datasource."oracle".jdbc.url=jdbc:oracle:///your_database
+----
+
+xref:config-reference.adoc#configuration-sources[Setting] `quarkus.hibernate-orm."pg".active=true` and `quarkus.datasource."pg".active=true` at runtime
+will make only the PostgreSQL persistence unit and datasource available,
+and setting `quarkus.hibernate-orm."oracle".active=true` and `quarkus.datasource."oracle".active=true` at runtime
+will make only the Oracle persistence unit and datasource available.
+
+[TIP]
+====
+xref:config-reference.adoc#custom-profiles[Custom configuration profiles] can help simplify such a setup.
+By appending the following profile-specific configuration to the one above,
+you can select a persistence unit/datasource at runtime simply by
+xref:config-reference.adoc#multiple-profiles[setting `quarkus.profile`]:
+`quarkus.profile=prod,pg` or `quarkus.profile=prod,oracle`.
+
+[source,properties]
+----
+%pg.quarkus.hibernate-orm."pg".active=true
+%pg.quarkus.datasource."pg".active=true
+# Add any pg-related runtime configuration here, prefixed with "%pg."
+
+%oracle.quarkus.hibernate-orm."oracle".active=true
+%oracle.quarkus.datasource."oracle".active=true
+# Add any pg-related runtime configuration here, prefixed with "%pg."
+----
+====
+
+[TIP]
+====
+It can also be useful to define a xref:cdi.adoc#ok-you-said-that-there-are-several-kinds-of-beans[CDI bean producer] redirecting to the currently active persistence unit,
+like this:
+
+[source,java,indent=0]
+----
+public class MyProducer {
+    @Inject
+    DataSourceSupport dataSourceSupport;
+
+    @Inject
+    @PersistenceUnit("pg")
+    Session pgSessionBean;
+
+    @Inject
+    @PersistenceUnit("oracle")
+    Session oracleSessionBean;
+
+    @Produces
+    @ApplicationScoped
+    public Session session() {
+        if (dataSourceSupport.getInactiveNames().contains("pg")) {
+            return oracleSessionBean;
+        } else {
+            return pgSessionBean;
+        }
+    }
+}
+----
+====
+
 [[persistence-xml]]
 == Setting up and configuring Hibernate ORM with a `persistence.xml`
 

extensions/agroal/deployment/src/main/java/io/quarkus/agroal/deployment/AgroalProcessor.java

@@ -24,10 +24,10 @@
 import io.agroal.api.AgroalDataSource;
 import io.agroal.api.AgroalPoolInterceptor;
 import io.quarkus.agroal.DataSource;
+import io.quarkus.agroal.runtime.AgroalDataSourceSupport;
 import io.quarkus.agroal.runtime.AgroalDataSourcesInitializer;
 import io.quarkus.agroal.runtime.AgroalRecorder;
 import io.quarkus.agroal.runtime.DataSourceJdbcBuildTimeConfig;
-import io.quarkus.agroal.runtime.DataSourceSupport;
 import io.quarkus.agroal.runtime.DataSources;
 import io.quarkus.agroal.runtime.DataSourcesJdbcBuildTimeConfig;
 import io.quarkus.agroal.runtime.JdbcDriver;
@@ -202,20 +202,20 @@ private static void validateBuildTimeConfig(AggregatedDataSourceBuildTimeConfigB
         }
     }
 
-    private DataSourceSupport getDataSourceSupport(
+    private AgroalDataSourceSupport getDataSourceSupport(
             List<AggregatedDataSourceBuildTimeConfigBuildItem> aggregatedBuildTimeConfigBuildItems,
             SslNativeConfigBuildItem sslNativeConfig, Capabilities capabilities) {
-        Map<String, DataSourceSupport.Entry> dataSourceSupportEntries = new HashMap<>();
+        Map<String, AgroalDataSourceSupport.Entry> dataSourceSupportEntries = new HashMap<>();
         for (AggregatedDataSourceBuildTimeConfigBuildItem aggregatedDataSourceBuildTimeConfig : aggregatedBuildTimeConfigBuildItems) {
             String dataSourceName = aggregatedDataSourceBuildTimeConfig.getName();
             dataSourceSupportEntries.put(dataSourceName,
-                    new DataSourceSupport.Entry(dataSourceName, aggregatedDataSourceBuildTimeConfig.getDbKind(),
+                    new AgroalDataSourceSupport.Entry(dataSourceName, aggregatedDataSourceBuildTimeConfig.getDbKind(),
                             aggregatedDataSourceBuildTimeConfig.getDataSourceConfig().dbVersion(),
                             aggregatedDataSourceBuildTimeConfig.getResolvedDriverClass(),
                             aggregatedDataSourceBuildTimeConfig.isDefault()));
         }
 
-        return new DataSourceSupport(sslNativeConfig.isExplicitlyDisabled(),
+        return new AgroalDataSourceSupport(sslNativeConfig.isExplicitlyDisabled(),
                 capabilities.isPresent(Capability.METRICS), dataSourceSupportEntries);
     }
 
@@ -247,10 +247,11 @@ void generateDataSourceSupportBean(AgroalRecorder recorder,
         unremovableBeans.produce(UnremovableBeanBuildItem.beanTypes(AgroalPoolInterceptor.class));
 
         // create the DataSourceSupport bean that DataSourceProducer uses as a dependency
-        DataSourceSupport dataSourceSupport = getDataSourceSupport(aggregatedBuildTimeConfigBuildItems, sslNativeConfig,
+        AgroalDataSourceSupport agroalDataSourceSupport = getDataSourceSupport(aggregatedBuildTimeConfigBuildItems,
+                sslNativeConfig,
                 capabilities);
-        syntheticBeanBuildItemBuildProducer.produce(SyntheticBeanBuildItem.configure(DataSourceSupport.class)
-                .supplier(recorder.dataSourceSupportSupplier(dataSourceSupport))
+        syntheticBeanBuildItemBuildProducer.produce(SyntheticBeanBuildItem.configure(AgroalDataSourceSupport.class)
+                .supplier(recorder.dataSourceSupportSupplier(agroalDataSourceSupport))
                 .unremovable()
                 .done());
     }

extensions/agroal/deployment/src/test/java/io/quarkus/agroal/test/AgroalMetricsConfigActiveFalseTest.java

@@ -0,0 +1,51 @@
+package io.quarkus.agroal.test;
+
+import jakarta.inject.Inject;
+
+import org.eclipse.microprofile.metrics.Counter;
+import org.eclipse.microprofile.metrics.Gauge;
+import org.eclipse.microprofile.metrics.MetricID;
+import org.eclipse.microprofile.metrics.MetricRegistry;
+import org.eclipse.microprofile.metrics.Tag;
+import org.eclipse.microprofile.metrics.annotation.RegistryType;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+
+public class AgroalMetricsConfigActiveFalseTest {
+
+    @RegisterExtension
+    static final QuarkusUnitTest config = new QuarkusUnitTest()
+            .withConfigurationResource("application-metrics-enabled.properties")
+            .overrideConfigKey("quarkus.datasource.active", "false")
+            .overrideConfigKey("quarkus.datasource.ds1.active", "false");
+
+    @Inject
+    @RegistryType(type = MetricRegistry.Type.VENDOR)
+    MetricRegistry registry;
+
+    @Test
+    public void testMetricsOfDefaultDS() {
+        Counter acquireCount = registry.getCounters()
+                .get(new MetricID("agroal.acquire.count", new Tag("datasource", "default")));
+        Gauge<?> maxUsed = registry.getGauges()
+                .get(new MetricID("agroal.max.used.count", new Tag("datasource", "default")));
+
+        Assertions.assertNull(acquireCount, "Agroal metrics should not be registered for deactivated datasources eagerly");
+        Assertions.assertNull(maxUsed, "Agroal metrics should not be registered for deactivated datasources eagerly");
+    }
+
+    @Test
+    public void testMetricsOfDs1() {
+        Counter acquireCount = registry.getCounters().get(new MetricID("agroal.acquire.count",
+                new Tag("datasource", "ds1")));
+        Gauge<?> maxUsed = registry.getGauges().get(new MetricID("agroal.max.used.count",
+                new Tag("datasource", "ds1")));
+
+        Assertions.assertNull(acquireCount, "Agroal metrics should not be registered for deactivated datasources eagerly");
+        Assertions.assertNull(maxUsed, "Agroal metrics should not be registered for deactivated datasources eagerly");
+    }
+
+}