Apply renders a CloudConfig to an Environment.

ExtractIPsFromMetaData parses a JSON blob in the OpenStack metadata service format and returns a substitution map possibly containing private_ipv4, public_ipv4, private_ipv6, and public_ipv6 addresses.

TODO(jonboulle): this is getting unwieldy, should be able to simplify the interface somehow.

ParseMetaData parses a JSON blob in the OpenStack metadata service format, and converts it to a partially hydrated CloudConfig.

CloudConfigFile represents a CoreOS specific configuration option that can generate an associated system.File to be written to disk.

CloudConfigUnit represents a CoreOS specific configuration option that can generate associated system.Units to be created/enabled appropriately.