code: func ValidateSecret(secret *api.Secret) field.ErrorList {
  	allErrs := ValidateObjectMeta(&secret.ObjectMeta, true, ValidateSecretName, field.NewPath("metadata"))
  
  	dataPath := field.NewPath("data")
  	totalSize := 0
  	for key, value := range secret.Data {
  		if !IsSecretKey(key) {
  			allErrs = append(allErrs, field.Invalid(dataPath.Key(key), key, fmt.Sprintf("must have at most %d characters and match regex %s", validation.DNS1123SubdomainMaxLength, SecretKeyFmt)))
  		}
  		totalSize += len(value)
  	}
  	if totalSize > api.MaxSecretSize {
  		allErrs = append(allErrs, field.TooLong(dataPath, "", api.MaxSecretSize))
  	}
  
  	switch secret.Type {
  	case api.SecretTypeServiceAccountToken:
  		// Only require Annotations[kubernetes.io/service-account.name]
  		// Additional fields (like Annotations[kubernetes.io/service-account.uid] and Data[token]) might be contributed later by a controller loop
  		if value := secret.Annotations[api.ServiceAccountNameKey]; len(value) == 0 {
  			allErrs = append(allErrs, field.Required(field.NewPath("metadata", "annotations").Key(api.ServiceAccountNameKey), ""))
  		}
  	case api.SecretTypeOpaque, "":
  	// no-op
  	case api.SecretTypeDockercfg:
  		dockercfgBytes, exists := secret.Data[api.DockerConfigKey]
  		if !exists {
  			allErrs = append(allErrs, field.Required(dataPath.Key(api.DockerConfigKey), ""))
  			break
  		}
  
  		// make sure that the content is well-formed json.
  		if err := json.Unmarshal(dockercfgBytes, &map[string]interface{}{}); err != nil {
  			allErrs = append(allErrs, field.Invalid(dataPath.Key(api.DockerConfigKey), "<secret contents redacted>", err.Error()))
  		}
  
  	default:
  		// no-op
  	}
  
  	return allErrs
  }
docs: // ValidateSecret tests if required fields in the Secret are set.