code: function loadConfigFile(dist, paths, options, callback) {
          if (options.config) {
              fs.readFile(options.config, {encoding: 'utf8'}, function(err, contents) {
                  if (err) {
                      callback(err);
                      return;
                  }
                  
                  var config = ini.parse(contents);
  
                  if (config && config.default) {
                      options.accessKeyId = config.default.access_key;
                      options.secretAccessKey = config.default.secret_key;
                  }
                  if (!options.secretAccessKey || !options.accessKeyId) {
                      callback("Config file missing access_key or secret_key");
                      return;
                  }
  
                  invalidate(dist, paths, options, callback);
              });
          } else {
              invalidate(dist, paths, options, callback);
          }
      }
docs: Function: loadConfigFile
  
  Wrapper around invalidate(). Adds AWS sercet and access from .ini config file if its set with --config.