Allow custom types on module outputs

[WhitWaldo]

I have a lot of modules, that, because of scoping, looping and organizational complexity pass a bunch of variables from the outputs back to the caller. Especially once I'm able to define these custom types in one place and import them around the solution, I'd like to be able to apply the outputs of a module as a custom type so I might trivially pass the output from the module into a parameter of another module using the same type rather than having to manually map it regularly on either end.

Especially if I'm able to rely on explicit and implicit validation on the values passed into these custom types, this would go a long way towards eliminating development error and assumptions about the values being shuffled between modules that violate constraints on dependencies.

An example of what I'd like to see (mixing one of my linked asks to simplify the example):

//kv-module.bicep
type resourceIdentifier = {
  subscriptionId: string
  resourceGroupName: string
  resourceName: string
}

param KeyVaultName string

resource KV 'Microsoft.KeyVault/vaults@2022-07-01' = {
  name: KeyVault.resourceName
  properties: {
    //...
  }
}

output KeyVaultResource resourceIdentifier = {
  subscriptionId: subscription().subscriptionId //I don't know this syntax is right - just scribbling this example off the top of my head
  resourceGroupName: resourceGroup().name
  resourceName: KeyVaultName
}

//other-module.bicep
type resourceIdentifier = {
  subscriptionId: string
  resourceGroupName: string
  resourceName: string
}

param KeyVaultId resourceIdentifier

module Doodad './other-other-module.bicep' = {
  //...
}

//root.bicep
module KV './kv-module.bicep' = {
  name: 'dp-kv-a'
  params: {
    KeyVaultName: 'mykeyvault'
  }
}

module OtherThing './other-module.bicep' = {
  name: 'dp-other'
  params: {
    KeyVaultId: KV.outputs.KeyVaultResource
  }
}

This would go a long way to not only bundle like-values into a single discrete type for downstream use from the output, but would also work to eliminate development-time errors (especially invalid scope assignments) by ensuring that when the input parameters require the type derived from an output, I just return that value directly from said output and eliminate an opportunity to mis-map that in some manner.

[santo2]

hey guys, where can I find the information about this? the import as specified above gives me an error. Is this expected?

[jeskew]

Hi @santo2, The import statement used in the issue description has not been implemented. This issue was just about using custom types on outputs; syntax for how to share types across templates is still being discussed in #10121.

I'll edit the imports out of the description to clarify what was implemented in #10052.

[santo2]

ok thanks for the feedback, guess I'll have to wait a bit longer :-)