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.
You may like to read the Quickstart guide if you want a very quick overview.
There is also a Gitter chatroom for you to ask any questions, suggest new features and talk to other users.