code: func splitDockerImageName(imageName string) (host, namespace, repo, tag string) {
  	hostNamespaceImage := strings.Split(imageName, "/")
  	last := len(hostNamespaceImage) - 1
  	repoTag := strings.Split(hostNamespaceImage[last], ":")
  	repo = repoTag[0]
  	if len(repoTag) > 1 {
  		tag = repoTag[1]
  	}
  	switch len(hostNamespaceImage) {
  	case 2:
  		host = ""
  		namespace = hostNamespaceImage[0]
  	case 3:
  		host = hostNamespaceImage[0]
  		namespace = hostNamespaceImage[1]
  	}
  	return
  }
docs: // splitDockerImageName split a docker image name of the form [HOST/][NAMESPACE/]REPOSITORY[:TAG]