Linter rule - what-if short circuiting

This rule detects when runtime values are passed as parameters to modules, which in turn use them to determine resource IDs (such as when the parameter is used to determine the name, subscriptionId, resourceGroup, condition, scope, or apiVersion of one or more resources within the module) , and flags potential what-if short-circuiting.

Linter rule code

Use the following value in the Bicep configuration file to customize rule settings:

what-if-short-circuiting

Solution

This rule checks for runtime values used to determine resource IDs within modules. It alerts you if your Bicep code could cause what-if short-circuiting. In the example below, appServiceOutputs and appServiceTests would be flagged for what-if short-circuiting because they pass runtime values as parameters to the module, which uses them when naming the resource:

main.bicep

resource storageAccount 'Microsoft.Storage/storageAccounts@2023-05-01' = {
  name: 'storageAccountName'
  location: 'chinanorth3'
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'StorageV2'
}

module appServiceModule 'modules/appService.bicep' = {
  name: 'appService2'
  params: {
    appServiceName: 'test'
  }
}

module appServiceOutputs 'modules/appService.bicep' = {
  name: 'appService3'
  params: {
    appServiceName: appServiceModule.outputs.outputName
  }
}

module appServiceTest 'modules/appService.bicep' = {
  name:'test3'
  params: {
    appServiceName: storageAccount.properties.accessTier
  }
}

modules/appService.bicep

param appServiceName string

resource appServiceApp 'Microsoft.Web/sites@2023-12-01' = {
  name: appServiceName
  location: 'chinanorth3'
  properties: {
    httpsOnly: true
  }
}

output outputName string = 'outputName'

To avoid this issue, use deployment-time constants for values that are used in determining resource IDs.

Next steps

For more information about the linter, see Use Bicep linter.