fuel-web (nailgun) implements REST API and deployment data management. It manages disk volumes configuration data, networks configuration data and any other environment specific data which are necessary for successful deployment. It has required orchestration logic to build instructions for provisioning and deployment in a right order. Nailgun uses SQL database to store its data and AMQP service to interact with workers.
Project status, bugs, and blueprints are tracked on Launchpad: https://launchpad.net/fuel
Development documentation is hosted here: https://docs.fuel-infra.org/fuel-dev
Any additional information can be found on the Fuel's project wiki https://wiki.openstack.org/wiki/Fuel
Anyone wishing to contribute to fuel-web should follow the general OpenStack process. A good reference for it can be found here: https://wiki.openstack.org/wiki/How_To_Contribute