Terraform-provider-azurerm: Support for adding new Backend Address Pool to an existing Application Gateway

[d-lee]

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Description

We would like an ability to add new backend pool to an existing application gateway without having to tear the gateway down. It is possible to do this via Azure CLI but Terraform doesn't seem to support such use-case.

[boillodmanuel]

I agree, and I would be great to be able to add any part of an application gateway as a separate resource
:

• azurerm_application_gateway_frontend_port
• azurerm_application_gateway_frontend_ip_configuration
• azurerm_application_gateway_backend_address_pool
• azurerm_application_gateway_backend_http_settings
• azurerm_application_gateway_http_listener_request_routing_rule
• azurerm_application_gateway

This could already be done with azurerm_loadbalancer and separate resources :

• azurerm_loadbalancer_backend_address_pool
• azurerm_loadbalancer_nat_rule
• azurerm_loadbalancer_outbound_rule
• azurerm_loadbalancer_probe
• azurerm_loadbalancer_rule

[boillodmanuel]

After some investigations, I notice theses resources are missing from the azure-sdk-for-go, so I opened 2 issues :

• azure-sdk-for-go : https://github.com/Azure/azure-sdk-for-go/issues/7234
• azure-rest-api-specs : https://github.com/Azure/azure-rest-api-specs/issues/8252

If anyone could vote for these root issues 👏

[tombuildsstuff]

@boillodmanuel both of those are blocked on this issue unfortunately: https://github.com/Azure/azure-rest-api-specs/issues/2313

[boillodmanuel]

Indeed @tombuildsstuff . I voted for this issue too. Thanks for sharing

[boillodmanuel]

Asked on azure feedback site: https://feedback.azure.com/forums/217313-networking/suggestions/39634588-add-rest-apis-and-sdk-to-manage-application-gatewa
If people following this issue could vote on it, it will be great 👍

[Dmitry1987]

Is this for real, there is no option to add a new backend address pool like in AWS ALB (a new target group to route to) when app-gateway is already operational in production??
Is it a TF module limitation or Azure cloud itself?