code: func GetEnvVarRefString(from *corev1.EnvVarSource) string {
  	if from.ConfigMapKeyRef != nil {
  		return fmt.Sprintf("configmap %s, key %s", from.ConfigMapKeyRef.Name, from.ConfigMapKeyRef.Key)
  	}
  
  	if from.SecretKeyRef != nil {
  		return fmt.Sprintf("secret %s, key %s", from.SecretKeyRef.Name, from.SecretKeyRef.Key)
  	}
  
  	if from.FieldRef != nil {
  		return fmt.Sprintf("field path %s", from.FieldRef.FieldPath)
  	}
  
  	if from.ResourceFieldRef != nil {
  		containerPrefix := ""
  		if from.ResourceFieldRef.ContainerName != "" {
  			containerPrefix = fmt.Sprintf("%s/", from.ResourceFieldRef.ContainerName)
  		}
  		return fmt.Sprintf("resource field %s%s", containerPrefix, from.ResourceFieldRef.Resource)
  	}
  
  	return "invalid valueFrom"
  }
docs: // GetEnvVarRefString returns a text description of whichever field is set within the supplied EnvVarSource argument.