Config File Requirements

ConfigFileRequirements

evan/tianon
My Immediate Needs:
- be able to extend the config file with new properties w/o breaking existing code
- in particular, I want to add new HTTP headers so I can add new code to docker to send them on each HTTP request

Longer-term things I think we'll need:
- allow for user to specify config file location when running docker (e.g docker --config <file> )
  I think this is mainly needed so we can run multiple CLIs at the same time and each can have its own
  config data - like auth headers, dockerHost, etc...  and asking users to pass all of this in on the
  cmd line or via env vars is a bit tedious.
- add Docker env vars to config file so 3rd party tooling can set them (e.g. DOCKER_HOST, http headers)

Next steps:
- modify existing code/config-file so that new properties can be added in a well-defined way that won't
  break the auth/registry code
- create PRs:
  1 - add new http headers to config file + code to send it to daemon
  2 - add DockerHost to config file if Machine needs it