code: func (sink *influxdbSink) GetSystemContainersFromNode(node string) ([]string, error) {
  	if !nameAllowedChars.MatchString(node) {
  		return nil, fmt.Errorf("Invalid node name %q", node)
  	}
  	// This is a bit difficult for the influx query language, so we cheat a bit here --
  	// we just get all series for the uptime measurement for system containers on our node
  	// (any measurement should work here, though)
  	q := fmt.Sprintf("SHOW SERIES FROM %q WHERE %s = '%s' AND type = '%s'", core.MetricUptime.MetricDescriptor.Name, core.LabelNodename.Key, node, core.MetricSetTypeSystemContainer)
  	return sink.stringListQueryCol(q, core.LabelContainerName.Key, fmt.Sprintf("Unable to list system containers on node %q", node))
  }
docs: // GetSystemContainersFromNode retrieves the list of free containers for a given node