[Bug Report]: resources/resource-group - ResourceGroupManagedByMismatch

[coolhome]

Describe the bug

Azure defaults ResourceGroup.managedBy as null but the ResourceModule template defaults to empty string. It is also not possible to set null with this module.

If I check if empty and send null then I get another error:

InvalidTemplate - Long running operation failed with status 'Failed'.
     | Additional Info:'Deployment template validation failed: 'The template
     | resource 'RG-Workday' at line '1' and column '2529' is not valid:
     | Evaluation result of language expression
     | '[if(empty(parameters('managedBy')), null(), parameters('managedBy'))]'
     | is type 'Null', expected type is 'String'.. Please see
     | https://aka.ms/arm-functions for usage details.'.

To reproduce

1. Create a resource group through azure portal
2. Create bicep for this resource group

module ResourceGroup '.carml/resources/resource-groups/main.bicep' = {
  name: '${deployment().name}-ResourceGroup'
  params: {
    name: resourceGroupName
    location: resourceGroupLocation
  }
}

3. Deploy Bicep

The managed by property of the resource group cannot be changed from its current value '<null>'

Code snippet

No response

Relevant log output

{
  "code": "DeploymentFailed",
  "target": "/subscriptions/***",
  "message": "At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.",
  "details": [
    {
      "code": "ResourceGroupManagedByMismatch",
      "message": "The managed by property of the resource group cannot be changed from its current value '<null>'."
    }
  ]
}

[zydio]

This also happens to any Resource Group deployed using CARML modules with v <= 0.8.0, when trying to deploy again the same BICEP with CARML v >= 0.9.0: the deployment will fail.

The PR that introduced the managedBy parameter is #2319 which was also erroneously marked as non-breaking change.. but as stated this breaks any existing deployment.

[adnkai]

Any news on this?

[coolhome]

I wonder if we should report this as a Resource Provider bug because I think the value should always be an immutable string. Alternatively, maybe there should be a ManagedResourceGroup module that separates this functionality out.

If you consume this module, I suggest removing the managedBy param.

[zydio]

I wonder if we should report this as a Resource Provider bug because I think the value should always be an immutable string. Alternatively, maybe there should be a ManagedResourceGroup module that separates this functionality out.

If you consume this module, I suggest removing the managedBy param.

I believe anyone using the module has been removing the managedBy param but this is a (painful) temporary workaround because it forces us to not use the stock modules: a proper fix should be available in CARML.