Added naming to migration bundles

docs/source/manual/migrations.rst

@@ -209,6 +209,104 @@ To mark a pending changeset as applied (e.g., after having backfilled your ``mig
 This will mark the next pending changeset as applied. You can also use the ``--all`` flag to mark
 all pending changesets as applied.
 
+Support For Adding Multiple Migration Bundles
+=============================================
+
+Assuming migrations need to be done for two different databases, you would need to have two different data source factories:
+
+.. code-block:: java
+
+    public class ExampleConfiguration extends Configuration {
+        @Valid
+        @NotNull
+        private DataSourceFactory database1 = new DataSourceFactory();
+
+        @Valid
+        @NotNull
+        private DataSourceFactory database2 = new DataSourceFactory();
+
+        @JsonProperty("database1")
+        public DataSourceFactory getDb1DataSourceFactory() {
+            return database1;
+        }
+
+        @JsonProperty("database2")
+        public DataSourceFactory getDb2DataSourceFactory() {
+            return database2;
+        }
+    }
+
+Now multiple migration bundles can be added with unique names like so:
+
+.. code-block:: java
+
+    @Override
+    public void initialize(Bootstrap<ExampleConfiguration> bootstrap) {
+        bootstrap.addBundle(new MigrationsBundle<ExampleConfiguration>() {
+            @Override
+            public DataSourceFactory getDataSourceFactory(ExampleConfiguration configuration) {
+                return configuration.getDb1DataSourceFactory();
+            }
+
+            @Override
+            public String name() {
+                return "db1";
+            }
+        });
+
+        bootstrap.addBundle(new MigrationsBundle<ExampleConfiguration>() {
+            @Override
+            public DataSourceFactory getDataSourceFactory(ExampleConfiguration configuration) {
+                return configuration.getDb2DataSourceFactory();
+            }
+
+            @Override
+            public String name() {
+                return "db2";
+            }
+        });
+    }
+
+To migrate your schema:
+
+.. code-block:: text
+
+    java -jar hello-world.jar db1 migrate helloworld.yml
+
+and
+
+.. code-block:: text
+
+    java -jar hello-world.jar db2 migrate helloworld.yml
+
+.. note::
+
+    Whenever a name is added to a migration bundle, it becomes the command that needs to be run at the command line.
+    eg: To check the state of your database, use the ``status`` command:
+
+.. code-block:: text
+
+    java -jar hello-world.jar db1 status helloworld.yml
+
+or
+
+.. code-block:: text
+
+    java -jar hello-world.jar db2 status helloworld.yml
+
+By default the migration bundle uses the "db" command. By overriding you can customize it to provide any name you want
+and have multiple migration bundles. Wherever the "db" command was being used, this custom name can be used.
+
+There will also be a need to provide different change log migration files as well. This can be done as
+
+.. code-block:: text
+
+    java -jar hello-world.jar db1 migrate helloworld.yml --migrations <path_to_db1_migrations.xml>
+
+.. code-block:: text
+
+    java -jar hello-world.jar db2 migrate helloworld.yml --migrations <path_to_db2_migrations.xml>
+
 More Information
 ================
 

dropwizard-migrations/src/main/java/io/dropwizard/migrations/DbCommand.java

@@ -13,8 +13,8 @@ public class DbCommand<T extends Configuration> extends AbstractLiquibaseCommand
     private static final String COMMAND_NAME_ATTR = "subcommand";
     private final SortedMap<String, AbstractLiquibaseCommand<T>> subcommands;
 
-    public DbCommand(DatabaseConfiguration<T> strategy, Class<T> configurationClass) {
-        super("db", "Run database migration tasks", strategy, configurationClass);
+    public DbCommand(String name, DatabaseConfiguration<T> strategy, Class<T> configurationClass) {
+        super(name, "Run database migration tasks", strategy, configurationClass);
         this.subcommands = new TreeMap<>();
         addSubcommand(new DbCalculateChecksumCommand<>(strategy, configurationClass));
         addSubcommand(new DbClearChecksumsCommand<>(strategy, configurationClass));

dropwizard-migrations/src/main/java/io/dropwizard/migrations/MigrationsBundle.java

@@ -7,11 +7,17 @@
 import io.dropwizard.setup.Environment;
 
 public abstract class MigrationsBundle<T extends Configuration> implements Bundle, DatabaseConfiguration<T> {
+    public static final String DEFAULT_NAME = "db";
+
     @Override
     @SuppressWarnings("unchecked")
     public final void initialize(Bootstrap<?> bootstrap) {
         final Class<T> klass = (Class<T>) bootstrap.getApplication().getConfigurationClass();
-        bootstrap.addCommand(new DbCommand<>(this, klass));
+        bootstrap.addCommand(new DbCommand<>(name(), this, klass));
+    }
+
+    protected String name() {
+        return DEFAULT_NAME;
     }
 
     @Override