code: func (c *Collector) getContainerMetrics() error {
  	u := url.URL{
  		Scheme: c.RequestProtocol,
  		Host:   net.JoinHostPort(c.nodeInfo.IPAddress, strconv.Itoa(c.Port)),
  		Path:   "/containers",
  	}
  
  	c.HTTPClient.Timeout = c.RequestTimeout
  
  	return client.Fetch(c.HTTPClient, u, &c.containerMetrics)
  }
docs: // poll queries an agent for container-level metrics, such as
  // CPU, memory, disk, and network usage.