no-reserved-resource-property

Id

@azure-tools/typespec-azure-resource-manager/no-reserved-resource-property

Reserved property names must not be present in a resource’s property bag. The property name is matched case-insensitively.

Reserved names are used by the ARM platform and common types; declaring them in RP-specific properties can conflict with standardized behavior.

This rule checks the immediate and inherited members of an ARM resource’s properties model. TypeSpec property names are matched case-insensitively and are disallowed regardless of their type.

Reserved name	Reason
billingData	Reserved for platform billing integration.
systemData	Resource system metadata belongs in the resource envelope, alongside id, name, and type, not in the properties bag.

Standard ARM resource templates already provide the envelope’s systemData. The rule does not recursively inspect nested objects or embedded resource envelopes.

The following examples assume a standard ARM resource whose properties model is WidgetProperties.

❌ Incorrect

model WidgetProperties {
  description?: string;
  billingData?: string;
  systemData?: {
    createdBy?: string;
  };
}

✅ Correct

model WidgetProperties {
  description?: string;
  billingInfo?: string;
}

Keep system metadata in the resource envelope rather than moving it into another resource-specific setting. Moving a property in an already released API changes its contract and requires compatibility review.

LintDiff Equivalent

This rule covers the direct ARM resource-properties-bag restriction from SystemDataInPropertiesBag. It does not reproduce the Swagger linter’s recursive search through arbitrary nested objects.