feat: allow db-migrate without version

Signed-off-by: David Goss <david@davidgoss.co>

api/src/main/java/marquez/MarquezApp.java

@@ -28,7 +28,7 @@
 import marquez.api.filter.JobRedirectFilter;
 import marquez.api.filter.exclusions.Exclusions;
 import marquez.api.filter.exclusions.ExclusionsConfig;
-import marquez.cli.DbMigrationCommand;
+import marquez.cli.DbMigrateCommand;
 import marquez.cli.DbRetentionCommand;
 import marquez.cli.MetadataCommand;
 import marquez.cli.SeedCommand;
@@ -90,6 +90,7 @@ public void initialize(@NonNull Bootstrap<MarquezConfig> bootstrap) {
             new EnvironmentVariableSubstitutor(ERROR_ON_UNDEFINED)));
 
     // Add CLI commands
+    bootstrap.addCommand(new DbMigrateCommand());
     bootstrap.addCommand(new DbRetentionCommand());
     bootstrap.addCommand(new MetadataCommand());
     bootstrap.addCommand(new SeedCommand());
@@ -202,12 +203,6 @@ public void registerResources(
     }
   }
 
-  @Override
-  protected void addDefaultCommands(Bootstrap<MarquezConfig> bootstrap) {
-    bootstrap.addCommand(new DbMigrationCommand<>(this));
-    super.addDefaultCommands(bootstrap);
-  }
-
   private void registerServlets(@NonNull Environment env) {
     log.debug("Registering servlets...");
 

api/src/main/java/marquez/cli/DbMigrateCommand.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018-2022 contributors to the Marquez project
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package marquez.cli;
+
+import io.dropwizard.cli.ConfiguredCommand;
+import io.dropwizard.db.DataSourceFactory;
+import io.dropwizard.db.ManagedDataSource;
+import io.dropwizard.setup.Bootstrap;
+import lombok.NonNull;
+import lombok.extern.slf4j.Slf4j;
+import marquez.MarquezConfig;
+import marquez.db.DbMigration;
+import net.sourceforge.argparse4j.inf.Namespace;
+
+/**
+ * A command to manually run database migrations. This command to be used to run migrations
+ * decoupled from application deployment.
+ */
+@Slf4j
+public class DbMigrateCommand extends ConfiguredCommand<MarquezConfig> {
+
+  public DbMigrateCommand() {
+    super("db-migrate", "A command to manually run database migrations.");
+  }
+
+  @Override
+  protected void run(
+      @NonNull Bootstrap<MarquezConfig> bootstrap,
+      @NonNull Namespace namespace,
+      @NonNull MarquezConfig configuration)
+      throws Exception {
+
+    final DataSourceFactory sourceFactory = configuration.getDataSourceFactory();
+    final ManagedDataSource source =
+        sourceFactory.build(bootstrap.getMetricRegistry(), "MarquezApp-source");
+
+    DbMigration.migrateDbOrError(configuration.getFlywayFactory(), source, true);
+  }
+}

api/src/main/java/marquez/db/DbMigration.java

@@ -25,15 +25,15 @@ public static void migrateDbOrError(@NonNull final DataSource source) {
   public static void migrateDbOrError(
       @NonNull final FlywayFactory flywayFactory,
       @NonNull final DataSource source,
-      final boolean migrateDbOnStartup) {
+      final boolean migrateNow) {
     final Flyway flyway = flywayFactory.build(source);
     // Only attempt a database migration if there are pending changes to be applied,
     // or on the initialization of a new database. Otherwise, error on pending changes
     // when the flag 'migrateOnStartup' is set to 'false'.
     if (!hasPendingDbMigrations(flyway)) {
       log.info("No pending migrations found, skipping...");
       return;
-    } else if (!migrateDbOnStartup && hasDbMigrationsApplied(flyway)) {
+    } else if (!migrateNow && hasDbMigrationsApplied(flyway)) {
       errorOnPendingDbMigrations(flyway);
     }
     // Attempt to perform a database migration. An exception is thrown on failed migration attempts