Provide API to run ddl and migration manually (e.g. with offline DB)

ebean-api/src/main/java/io/ebean/Database.java

@@ -1741,4 +1741,26 @@ public interface Database {
    */
   void truncate(Class<?>... tables);
 
+  /**
+   * Runs the DDL manually. Can be used, if database is offline or if you use a
+   * TenantMode that does not support DDL run on startup.
+   * <p>
+   * Note: runDdl is normally executed at startup automatically, if
+   * <code>ebean.db.runDdl=true</code> is set. Calling this method, will not check
+   * that flag.
+   * </p>
+   */
+  void runDdl();
+
+  /**
+   * Runs the migration manually. Can be used, if database is offline or if you use a
+   * TenantMode that does not support DDL run on startup.
+   * <p>
+   * Note: runDdl is normally executed at startup automatically, if
+   * <code>ebean.db.migration.run=true</code> is set. Calling this method, will not check
+   * that flag.
+   * </p>
+   **/
+  void runMigration();
+
 }

ebean-core/src/main/java/io/ebeaninternal/api/SpiDdlGenerator.java

@@ -8,8 +8,14 @@ public interface SpiDdlGenerator {
   /**
    * Generate and run the DDL for drop-all and create-all scripts.
    * <p>
-   * Run based on on property settings for ebean.ddl.generate and ebean.ddl.run etc.
+   * Run based on on property settings for ebean.ddl.generate
    */
-  void execute(boolean online);
+  void generateDdl();
 
+  /**
+   * Runs the created DDL files.
+   * <p>
+   * Run based on on property settings for ebean.ddl.run etc.
+   */
+  void runDdl();
 }

ebean-core/src/main/java/io/ebeaninternal/server/core/DefaultServer.java

@@ -246,7 +246,7 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
    */
   public void executePlugins(boolean online) {
     if (!config.isDocStoreOnly()) {
-      ddlGenerator.execute(online);
+      ddlGenerator.generateDdl();
     }
     for (Plugin plugin : serverPlugins) {
       plugin.online(online);
@@ -359,27 +359,54 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
     serverCacheManager.enabledRegions(config.getEnabledL2Regions());
   }
 
+
   /**
    * Start any services after registering with the ClusterManager.
    */
   public void start() {
-    if (config.isRunMigration() && TenantMode.DB != config.getTenantMode()) {
-      final AutoMigrationRunner migrationRunner = ServiceUtil.service(AutoMigrationRunner.class);
-      if (migrationRunner == null) {
-        throw new IllegalStateException("No AutoMigrationRunner found. Probably ebean-migration is not in the classpath?");
+
+    // check, if DB is available to run DDL and migration
+    boolean dbAvailable = !config.isDocStoreOnly() 
+        && !config.isDbOffline() 
+        && config.getDataSource() != null
+        && config.getTenantMode().isDdlEnabled();
+
+    if (dbAvailable) {
+      if (config.isDdlRun()) {
+        runDdl();
       }
-      final String dbSchema = config.getDbSchema();
-      if (dbSchema != null) {
-        migrationRunner.setDefaultDbSchema(dbSchema);
+      if (config.isRunMigration()) {
+        runMigration();
       }
-      migrationRunner.setName(config.getName());
-      migrationRunner.setPlatform(config.getDatabasePlatform().getPlatform().base().name().toLowerCase());
-      migrationRunner.loadProperties(config.getProperties());
-      migrationRunner.run(config.getDataSource());
+    } else if (config.isDdlRun() || config.isRunMigration()) {
+      log.warn("There was a request to run DDL or migration, but this is currently not possible, as the database is not available");
     }
     startQueryPlanCapture();
   }
 
+  @Override
+  public void runDdl() {
+    ddlGenerator.runDdl();
+  }
+
+  @Override
+  public void runMigration() {
+    final AutoMigrationRunner migrationRunner = ServiceUtil.service(AutoMigrationRunner.class);
+    if (migrationRunner == null) {
+      throw new IllegalStateException(
+          "No AutoMigrationRunner found. Probably ebean-migration is not in the classpath?");
+    }
+
+    final String dbSchema = config.getDbSchema();
+    if (dbSchema != null) {
+      migrationRunner.setDefaultDbSchema(dbSchema);
+    }
+    migrationRunner.setName(config.getName());
+    migrationRunner.setPlatform(config.getDatabasePlatform().getPlatform().base().name().toLowerCase());
+    migrationRunner.loadProperties(config.getProperties());
+    migrationRunner.run(dataSource());
+  }
+
   private void startQueryPlanCapture() {
     if (config.isQueryPlanCapture()) {
       long secs = config.getQueryPlanCapturePeriodSecs();

ebean-core/src/main/java/io/ebeaninternal/server/core/InternalConfiguration.java

@@ -610,8 +610,13 @@ public final class InternalConfiguration {
     }
 
     @Override
-    public void execute(boolean online) {
-      if (online && ddlRun) {
+    public void generateDdl() {
+      // do nothing
+    }
+    
+    @Override
+    public void runDdl() {
+      if (ddlRun) {
         CoreLog.log.error("Configured to run DDL but ebean-ddl-generator is not in the classpath (or ebean-test in the test classpath?)");
       }
     }

ebean-ddl-generator/src/main/java/io/ebeaninternal/dbmigration/DdlGenerator.java

@@ -41,7 +41,6 @@ public class DdlGenerator implements SpiDdlGenerator {
   private final SpiEbeanServer server;
 
   private final boolean generateDdl;
-  private final boolean runDdl;
   private final boolean extraDdl;
   private final boolean createOnly;
   private final boolean jaxbPresent;
@@ -67,14 +66,7 @@ public class DdlGenerator implements SpiDdlGenerator {
     final DatabasePlatform databasePlatform = server.databasePlatform();
     this.platform = databasePlatform.getPlatform();
     this.platformName = platform.base().name();
-    if (!config.getTenantMode().isDdlEnabled() && config.isDdlRun()) {
-      log.warn("DDL can't be run on startup with TenantMode " + config.getTenantMode());
-      this.runDdl = false;
-      this.ddlAutoCommit = false;
-    } else {
-      this.runDdl = config.isDdlRun();
-      this.ddlAutoCommit = databasePlatform.isDdlAutoCommit();
-    }
+    this.ddlAutoCommit = databasePlatform.isDdlAutoCommit();
     this.scriptTransform = createScriptTransform(config);
     this.baseDir = initBaseDir();
   }
@@ -89,18 +81,11 @@ public class DdlGenerator implements SpiDdlGenerator {
     return new File(".");
   }
 
-  @Override
-  public void execute(boolean online) {
-    generateDdl();
-    if (online) {
-      runDdl();
-    }
-  }
-
   /**
    * Generate the DDL drop and create scripts if the properties have been set.
    */
-  protected void generateDdl() {
+  @Override
+  public void generateDdl() {
     if (generateDdl) {
       if (!createOnly) {
         writeDrop(getDropFileName());
@@ -112,16 +97,15 @@ public class DdlGenerator implements SpiDdlGenerator {
   /**
    * Run the DDL drop and DDL create scripts if properties have been set.
    */
-  protected void runDdl() {
-    if (runDdl) {
-      Connection connection = null;
-      try {
-        connection = obtainConnection();
-        runDdlWith(connection);
-      } finally {
-        JdbcClose.rollback(connection);
-        JdbcClose.close(connection);
-      }
+  @Override  
+  public void runDdl() {
+    Connection connection = null;
+    try {
+      connection = obtainConnection();
+      runDdlWith(connection);
+    } finally {
+      JdbcClose.rollback(connection);
+      JdbcClose.close(connection);
     }
   }
 

ebean-test/src/test/java/io/ebean/config/TestServerOffline.java

@@ -0,0 +1,151 @@
+package io.ebean.config;
+
+
+import io.ebean.Database;
+import io.ebean.DatabaseFactory;
+import io.ebean.annotation.ForPlatform;
+import io.ebean.annotation.Platform;
+import io.ebean.datasource.DataSourceAlert;
+import io.ebean.datasource.DataSourceInitialiseException;
+
+import org.junit.jupiter.api.Test;
+import org.tests.model.basic.EBasicVer;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Properties;
+
+import javax.persistence.PersistenceException;
+import javax.sql.DataSource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class TestServerOffline {
+
+  @Test
+  @ForPlatform({Platform.H2})
+  public void testOffline_default() throws SQLException {
+
+    String url = "jdbc:h2:mem:testoffline1";
+    try (Connection bootup = DriverManager.getConnection(url, "sa", "secret")) {
+      Properties props = props(url);
+      DatabaseConfig config = config(props);
+
+      assertThatThrownBy(() -> DatabaseFactory.create(config))
+        .isInstanceOf(DataSourceInitialiseException.class);
+   }
+
+  }
+
+  private static class LazyDatasourceInitializer implements DataSourceAlert {
+
+    public Database server;
+
+    private boolean initialized;
+
+    @Override
+    public void dataSourceUp(DataSource dataSource) {
+      if (!initialized) {
+        initDatabase();
+      }
+    }
+
+    public synchronized void initDatabase() {
+      if (!initialized) {
+        server.runDdl();
+        server.runMigration();
+        initialized = true;
+      }
+    }
+
+    @Override
+    public void dataSourceDown(DataSource dataSource, SQLException reason) {}
+
+    @Override
+    public void dataSourceWarning(DataSource dataSource, String msg) {}
+
+  }
+
+  @Test
+  @ForPlatform({Platform.H2})
+  public void testOffline_recovery() throws SQLException {
+
+    String url = "jdbc:h2:mem:testoffline3";
+    try (Connection bootup = DriverManager.getConnection(url, "sa", "secret")) {
+
+      Properties props = props(url);
+
+      // to bring up ebean without a database, we must disable varous things
+      // that happen on startup
+      props.setProperty("datasource.h2_offline.failOnStart", "false");
+      props.setProperty("ebean.h2_offline.skipDataSourceCheck", "true");
+      props.setProperty("ebean.h2_offline.ddl.run", "false");
+      DatabaseConfig config = config(props);
+
+      LazyDatasourceInitializer alert = new LazyDatasourceInitializer() ;
+      config.getDataSourceConfig().setAlert(alert);
+      config.getDataSourceConfig().setHeartbeatFreqSecs(1);
+      
+      Database h2Offline = DatabaseFactory.create(config);
+      alert.server = h2Offline;
+      assertThat(h2Offline).isNotNull();
+      // DB is online now in offline mode
+
+      // Accessing the DB will throw a PE
+      assertThatThrownBy(() -> alert.initDatabase())
+        .isInstanceOf(PersistenceException.class)
+        .hasMessageContaining("Failed to obtain connection to run DDL");
+
+      assertThatThrownBy(() -> h2Offline.find(EBasicVer.class).findCount()).isInstanceOf(PersistenceException.class);
+
+      // so - reset the password so that the server can reconnect
+      try (Statement stmt = bootup.createStatement()) {
+        stmt.execute("alter user sa set password 'sa'");
+      }
+
+      assertThat(alert.initialized).isFalse();
+      
+      // next access to ebean should bring DS online
+      h2Offline.find(EBasicVer.class).findCount();
+      assertThat(alert.initialized).isTrue();
+
+      // check if server is working (ie ddl was run)
+      EBasicVer bean = new EBasicVer("foo");
+      h2Offline.save(bean);
+      assertThat(h2Offline.find(EBasicVer.class).findCount()).isEqualTo(1);
+      h2Offline.delete(bean);
+    }
+  }
+
+  private Properties props(String url) {
+
+    Properties props = new Properties();
+
+    props.setProperty("datasource.h2_offline.username", "sa");
+    props.setProperty("datasource.h2_offline.password", "sa");
+    props.setProperty("datasource.h2_offline.url", url);
+    props.setProperty("datasource.h2_offline.driver", "org.h2.Driver");
+
+    props.setProperty("ebean.h2_offline.databasePlatformName", "h2");
+    props.setProperty("ebean.h2_offline.ddl.extra", "false");
+
+    props.setProperty("ebean.h2_offline.ddl.generate", "true");
+    props.setProperty("ebean.h2_offline.ddl.run", "true");
+
+    return props;
+  }
+
+  private DatabaseConfig config(Properties props) {
+    DatabaseConfig config = new DatabaseConfig();
+    config.setName("h2_offline");
+    config.loadFromProperties(props);
+    config.setDefaultServer(false);
+    config.setRegister(false);
+    config.getClasses().add(EBasicVer.class);
+    return config;
+  }
+
+}

ebean-test/src/test/java/io/ebeaninternal/api/TDSpiServer.java

@@ -642,4 +642,14 @@ public class TDSpiServer implements SpiServer {
   public void loadBean(EntityBeanIntercept ebi) {
 
   }
+
+  @Override
+  public void runDdl() {
+
+  }
+
+  @Override
+  public void runMigration() {
+
+  }
 }