Azure Bicep: Create ServiceBus subscription in existing namespace from another Resource Group

Question

I have an existing ServiceBus namespace and Topic in Resource Group A, and I am working on a new bicep template that will deploy resources to Resource Group B, in this template I have to create a new Subscription to the Topic that is in Resource Group A.

I have tried following till now without any success:

param EngineServiceBus string
param EngineTopicName string
param EngineMatasPlusSubscriber string

resource EngineServicebus 'Microsoft.ServiceBus/namespaces@2022-10-01-preview' existing = {
  name: EngineServiceBus
  scope: resourceGroup(offerEngineRG)
}
resource EngineTopic 'Microsoft.ServiceBus/namespaces/topics@2022-10-01-preview' existing = {
  name: EngineTopicName
  parent: EngineServicebus

}

resource EngineSubscriber 'Microsoft.ServiceBus/namespaces/topics/subscriptions@2022-10-01-preview' = {
  name: '${EngineServicebus.name}/${EngineTopic.name}/${EngineMatasPlusSubscriber}'
}

Answer 1

When invoking this module from your parent bicep file, you need to scopes the module to the resource group.

In your subscription module, remove the scope:

// subscription.bicep

param EngineServiceBus string
param EngineTopicName string
param EngineMatasPlusSubscriber string

resource EngineServicebus 'Microsoft.ServiceBus/namespaces@2022-10-01-preview' existing = {
  name: EngineServiceBus
}
resource EngineTopic 'Microsoft.ServiceBus/namespaces/topics@2022-10-01-preview' existing = {
  name: EngineTopicName
  parent: EngineServicebus

}

resource EngineSubscriber 'Microsoft.ServiceBus/namespaces/topics/subscriptions@2022-10-01-preview' = {
  name: EngineMatasPlusSubscriber
  parent: EngineTopic
}

Then from the parent, add the scope on the module

param offerEngineRG string
param EngineServiceBus string
param EngineTopicName string
param EngineMatasPlusSubscriber string

module createSubscription 'subscription.bicep' = {
  name: '...'
  scope: resourceGroup(offerEngineRG) // scope of the deployment
  params: {    
    EngineServiceBus: EngineServiceBus
    EngineTopicName: EngineTopicName
    EngineMatasPlusSubscriber: EngineMatasPlusSubscriber
  }
}