scope property in deployment() function

[slavizh]

Is your feature request related to a problem? Please describe.
We have function like subscription() and soon to have managementGroup(). There are a few resources that allow to deployed at both subscription and management group scopes. The difference when these resources are deployed at these two scopes are minor. For example the main differences I have seen are:

• cannot deploy resource group at mg level
• policy definition and assignment names needs to be maximum 24 characters at management group level (at sub level it is higher number). No idea why this limit exists but it is there.
  With that said if you want to create one bicep solution that can deploy the applicable resources to both scopes it is good that you can use managementGroup() or subscription() function depending on the scope the deployment happens.

Describe the solution you'd like
the solution would be something like:

var someVar = deployment().scope =~ 'subscription' ? subscription().id : managementGroup().id

[slavizh]

/cc @alex-frankel @anthony-c-martin

[alex-frankel]

In order for this property to be useful, do we need to finish #788?

[anthony-c-martin]

In order for this property to be useful, do we need to finish #788?

That was my motivation for supporting it, because it allows Bicep to generate resourceId expressions that are scope-agnostic.

Note that I was imagining a different implementation to @slavizh though - I was thinking it would return the actual value of the scope - e.g. /subscriptions/<subId>, /subscriptions/<subId>/resourceGroups/<rgName>, / or /providers/Microsoft.Management/managementGroups/<mgName>.

That would allow Bicep to codegen resourceId expressions with the following format:

"[extensionResourceId(
    deployment().scope,
    'My.Rp/myType',
    variables('resourceName')
)]"

[slavizh]

@anthony-c-martin I guess we just need to think of all the possible options for such scenario. Though probably there still might be useful to be able to use subscription() or managementGroup() depending on the scope. As they might use some of the properties in those functions for other functions like uniqueString, concat, etc.