Bicep - Do you use User-defined Data Types?

<introEmbed body={<> [User-defined data types in Bicep](https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/user-defined-data-types?WT.mc_id=DP-MVP-33518) allow you to create custom data structures for better code organization and type safety. They enhance reusability, abstraction, and maintainability within projects. </>} />

When creating a cloud resource, numerous parameters are typically required for configuration and customization. Organizing and naming these parameters effectively is increasingly important.

@allowed(['Basic', 'Standard'])
param skuName string = 'Basic'
@allowed([5, 10, 20, 50, 100])
param skuCapacity int = 5
param skuSizeInGB int = 2

❌ Figure: Bad example - Relying on parameter prefixes and order leads to unclear code, high complexity, and increased maintenance effort

param sku object

❌ Figure: Bad example - When declaring a parameter as an untyped object, bicep cannot validate the object's properties and values at compile time, risking runtime errors.

// User-defined data type
type skuConfig = {
  name: 'Basic' | 'Standard'
  capacity: 5 | 10 | 20 | 50 | 100
  sizeInGB: int
}

param sku skuConfig = {
  name: 'Basic'
  capacity: 5
  sizeInGB: 2
}

✅ Figure: Good example - User-defined data type provides type safety, enhanced readability and making maintenance easier