Balrog is a rewrite of the Application Update Server used by Mozilla to provide updates to Firefox. It uses a database to store a series of rules which map update requests to releases. Documentation is available at https://wiki.mozilla.org/Balrog. To run a development environment you must have Docker and docker-compose installed (if you're on Windows or Mac you need "Docker for Windows" or "Docker for Mac" at least v1.12.0). Once these prerequisites are installed, run the following command to create and run the necessary images: docker-compose up MySQL data will persist across runs and stored under `.cache/mysql`. To reset the data, you can delete the directory and run `docker-compose up`. Now you should be able to access the admin interface at: http://127.0.0.1:8080 And you can access the public interface with URLs such as: http://127.0.0.1:9090/update/3/Firefox/33.0/20141202185629/Darwin_x86_64-gcc3-u-i386-x86_64/en-US/release/default/default/default/update.xml?force=1