How to configure multiple DataSources for multitenancy in Hibernate

Question

I am trying to add multitenancy to a java application using the separate schema approach as outlined in this webinar

I wanted to know how would I configure multiple

Answer 1

As I explained in this article, the routing can be done by Hibernate via its MultiTenancyConnectionProvider which you can implement like this:

public class MultiTenantConnectionProvider
        extends AbstractMultiTenantConnectionProvider {

    public static final MultiTenantConnectionProvider INSTANCE =
            new MultiTenantConnectionProvider();

    private final Map connectionProviderMap = 
            new HashMap<>();

    Map getConnectionProviderMap() {
        return connectionProviderMap;
    }

    @Override
    protected ConnectionProvider getAnyConnectionProvider() {
        return connectionProviderMap.get(
            TenantContext.DEFAULT_TENANT_IDENTIFIER
        );
    }

    @Override
    protected ConnectionProvider selectConnectionProvider(
            String tenantIdentifier) {
        return connectionProviderMap.get(
            tenantIdentifier
        );
    }
}

Assuming each tenant uses its own dedicated DataSource, you can register the individual ConnectionProviders using a utility method like this one:

private void addTenantConnectionProvider(
        String tenantId, 
        DataSource tenantDataSource, 
        Properties properties) {

    DatasourceConnectionProviderImpl connectionProvider = 
        new DatasourceConnectionProviderImpl();
    connectionProvider.setDataSource(tenantDataSource);
    connectionProvider.configure(properties);

    MultiTenantConnectionProvider.INSTANCE
    .getConnectionProviderMap()
    .put(
        tenantId, 
        connectionProvider
    );
}

You can register a default tenant for admin-related tasks:

addTenantConnectionProvider(
    TenantContext.DEFAULT_TENANT_IDENTIFIER, 
    defaultDataSource, 
    properties()
);

And for the actual tenants, you could use a method like this one:

private void addTenantConnectionProvider(
        String tenantId) {

    DataSourceProvider dataSourceProvider = database()
    .dataSourceProvider();

    Properties properties = properties();

    MysqlDataSource tenantDataSource = new MysqlDataSource();
    tenantDataSource.setDatabaseName(tenantId);
    tenantDataSource.setUser(dataSourceProvider.username());
    tenantDataSource.setPassword(dataSourceProvider.password());

    properties.put(
        Environment.DATASOURCE,
        dataSourceProxyType().dataSource(tenantDataSource)
    );

    addTenantConnectionProvider(
        tenantId, 
        tenantDataSource, 
        properties
    );
}

You can change the MysqlDataSource to whatever database you are using.

Then, registering the tenants is as simple as that:

addTenantConnectionProvider("asia");
addTenantConnectionProvider("europe");

The last thing to take into consideration is to provide the MultiTenancyConnectionProvider implementation to Hibernate via the hibernate.multi_tenant_connection_provider configuration property.

properties.put(
    AvailableSettings.MULTI_TENANT_CONNECTION_PROVIDER, 
    MultiTenantConnectionProvider.INSTANCE
);