Magento 2 provides a separated module for data migration: magento/data-migration-tool. During the migration, it needs to customize this module and implement some additional steps to port 3rd-party customizations. Right now, we have the following changes in the .gitignore file of the project:
!/vendor/magento/data-migration-tool/etc/commerce-to-commerce/126.96.36.199/config.xml !/vendor/magento/data-migration-tool/etc/commerce-to-commerce/188.8.131.52/map.xml !/vendor/magento/data-migration-tool/etc/commerce-to-commerce/settings.xml !/vendor/magento/data-migration-tool/etc/commerce-to-commerce/map-sales.xml !vendor/magento/data-migration-tool/etc/commerce-to-commerce/eav-attribute-groups.xml !vendor/magento/data-migration-tool/src/Migration/Step/Claims/*
Is there any best practice how to extend this module? During magento porting, version of Magento 2 is being updating that's why the tool is being updated as well and it's important to save changes there.