Tiller is a tool that generates configuration files. It takes a set of templates, fills them in with values from a variety of sources (such as environment variables, Consul, YAML files, JSON from a webservice...), installs them in a specified location and then optionally spawns a child process.
You might find this particularly useful if you're using Docker, as you can ship a set of configuration files for different environments inside one container, and/or easily build "parameterized containers" which users can then configure at runtime.
However, its use is not just limited to Docker; you may also find it useful as a sort of "proxy" that can provide values to application configuration files from a data source that the application does not natively support.
It's available as a Ruby Gem, so installation should be a simple gem install tiller.
The main documentation has been updated and a searchable, easy to read version is now hosted on readthedocs.io. You can also read the raw markdown files by browsing the docs directory in this repository.
There is also a Gitter chatroom for you to ask any questions, suggest new features and talk to other users.