module ChefConfig::Mixin::TrainTransport

def credentials_file_path


3) #credentials_file_path from parent ($HOME/.chef/credentials)
2) /etc/chef/TARGET_MODE_HOST/credentials
1) target_mode.credentials_file

Credentials file preference:

overriding it here.
ChefConfig::Mixin::Credentials.credentials_file_path is designed around knife, 
def credentials_file_path
  tm_config = config.target_mode
  profile = tm_config.host
  credentials_file =
    if tm_config.credentials_file && File.exist?(tm_config.credentials_file)
      tm_config.credentials_file
    elsif File.exist?(config.platform_specific_path("#{ChefConfig::Config.etc_chef_dir}/#{profile}/credentials"))
      config.platform_specific_path("#{ChefConfig::Config.etc_chef_dir}/#{profile}/credentials")
    else
      super
    end
  raise ArgumentError, "No credentials file found for target '#{profile}'" unless credentials_file
  raise ArgumentError, "Credentials file specified for target mode does not exist: '#{credentials_file}'" unless File.exist?(credentials_file)
  logger.debug("Loading credentials file '#{credentials_file}' for target '#{profile}'")
  credentials_file
end