code: func getDockerClient(dockerEndpoint string) (*dockerapi.Client, error) {
  	if len(dockerEndpoint) > 0 {
  		klog.Infof("Connecting to docker on %s", dockerEndpoint)
  		return dockerapi.NewClient(dockerEndpoint, "", nil, nil)
  	}
  	return dockerapi.NewEnvClient()
  }
docs: // Get a *dockerapi.Client, either using the endpoint passed in, or using
  // DOCKER_HOST, DOCKER_TLS_VERIFY, and DOCKER_CERT path per their spec