[AVM Module Issue]: Support for Application Gateway Backend Pool placement in different subscription

[konopkap]

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Issue Type?

Feature Request

(Optional) Module Version

0.20.0

(Optional) Correlation Id

No response

Description

Currently adding VM to Application Gateway Backend Pool is supported via network_interfaces.[].ip_configurations.[].app_gateway_backend_pools.[].app_gateway_backend_pool_resource_id variable. However it works only if both VM and Application Gateway are in the same subscription (effectively using the same Terraform provider).

It's common scenario to have Application Gateway in separate subscription than VMs are deployed to - hence it would be useful to support that as well (exposing possibility to pass different provider for Backend Pool configuration).

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For additional guidance on how to triage this issue/PR, see the Terraform Issue Triage documentation.

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Tagging the AVM Core Team (@Azure/avm-core-team-technical-terraform) due to a module owner or contributor having not responded to this issue within 3 business days. The AVM Core Team will attempt to contact the module owners/contributors directly.

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[microsoft-github-policy-service]

Caution

**This issue requires the AVM Core Team's (@Azure/avm-core-team-technical-terraform) immediate attention as it hasn't been responded to within 6 business days. **

Tip

• To avoid this rule being (re)triggered, the "Needs: Triage 🔍" and "Status: Response Overdue 🚩" labels must be removed when the issue is first responded to!
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