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Dropwizard Migrations

The dropwizard-migrations module provides you with a wrapper for Liquibase database refactoring.

Configuration

Like Dropwizard JDBI, your configuration class needs a DatabaseConfiguration instance:

public class ExampleConfiguration extends Configuration {
    @Valid
    @NotNull
    @JsonProperty
    private DatabaseConfiguration database = new DatabaseConfiguration();

    public DatabaseConfiguration getDatabaseConfiguration() {
        return database;
    }
}

Adding The Bundle

Then, in your service’s initialize method, add a new MigrationsBundle subclass:

@Override
public void initialize(Bootstrap<MyConfiguration> bootstrap) {
    bootstrap.addBundle(new MigrationsBundle<MyConfiguration>() {
        @Override
        public DatabaseConfiguration getDatabaseConfiguration(MyConfiguration configuration) {
            return configuration.getDatabaseConfiguration();
        }
    });
}

Defining Migrations

Your database migrations are stored in your Dropwizard project, in src/main/resources/migrations.xml. This file will be packaged with your service, allowing you to run migrations using your service’s command-line interface.

For example, to create a new people table, I might create an initial migrations.xml like this:

<?xml version="1.0" encoding="UTF-8"?>

<databaseChangeLog
        xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
         http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-2.0.xsd">

    <changeSet id="1" author="codahale">
        <createTable tableName="people">
            <column name="id" type="bigint" autoIncrement="true">
                <constraints primaryKey="true" nullable="false"/>
            </column>
            <column name="fullName" type="varchar(255)">
                <constraints nullable="false"/>
            </column>
            <column name="jobTitle" type="varchar(255)"/>
        </createTable>
    </changeSet>
</databaseChangeLog>

For more information on available database refactorings, check the Liquibase documentation.

Checking Your Database’s State

To check the state of your database, use the db status command:

java -jar hello-world.jar db status helloworld.yml

Dumping Your Schema

If your database already has an existing schema and you’d like to pre-seed your migrations.xml document, you can run the db dump command:

java -jar hello-world.jar db dump helloworld.yml

This will output a Liquibase change log with a change set capable of recreating your database.

Tagging Your Schema

To tag your schema at a particular point in time (e.g., to make rolling back easier), use the db tag command:

java -jar hello-world.jar db tag helloworld.yml 2012-10-08-pre-user-move

Migrating Your Schema

To apply pending change sets to your database schema, run the db migrate comnand:

java -jar hello-world.jar db migrate helloworld.yml

Warning

This will potentially make irreversible changes to your database. Always check the pending DDL scripts by using the --dry-run flag first. This will output the SQL to be run to stdout.

Note

To apply only a specific number of pending change sets, use the --count flag.

Rolling Back Your Schema

To roll back change sets which have already been applied, run the db rollback command. You will need to specify either a tag, a date, or a number of change sets to roll back to:

java -jar hello-world.jar db rollback helloworld.yml --tag 2012-10-08-pre-user-move

Warning

This will potentially make irreversible changes to your database. Always check the pending DDL scripts by using the --dry-run flag first. This will output the SQL to be run to stdout.

Testing Migrations

To verify that a set of pending change sets can be fully rolled back, use the db test command, which will migrate forward, roll back to the original state, then migrate forward again:

java -jar hello-world.jar db test helloworld.yml

Warning

Do not run this in production, for obvious reasons.

Preparing A Rollback Script

To prepare a rollback script for pending change sets before they have been applied, use the db prepare-rollback command:

java -jar hello-world.jar db prepare-rollback helloworld.yml

This will output a DDL script to stdout capable of rolling back all unapplied change sets.

Generating Documentation

To generate HTML documentation on the current status of the database, use the db generate-docs command:

java -jar hello-world.jar db generate-docs helloworld.yml ~/db-docs/

Dropping All Objects

To drop all objects in the database, use the db drop-all command:

java -jar hello-world.jar db drop-all --confirm-delete-everything helloworld.yml

Warning

You need to specify the --confirm-delete-everything flag because this command deletes everything in the database. Be sure you want to do that first.

Fast-Forwarding Through A Change Set

To mark a pending change set as applied (e.g., after having backfilled your migrations.xml with db dump), use the db fast-forward command:

java -jar hello-world.jar db fast-forward helloworld.yml

This will mark the next pending change set as applied. You can also use the --all flag to mark all pending change sets as applied.

More Information

For more information on available commands, either use the db --help command, or for more detailed help on a specific command, use db <cmd> --help.