Conditionals for application gateway backend pools

[PleaseStopAsking]

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Description

It would be helpful if there was a way to conditionally create certain arguments when using the application gateway resource. Specifically, I would like to be able to create additional backend_address_pool, probe, backend_http_settings and path_rule based on a true/false variable that I am also using to conditionally deploy extra servers behind the application gateway.

New or Affected Resource(s)

azurerm_application_gateway

Potential Terraform Configuration

resource "azurerm_application_gateway" "appGateway" {
 ...

  backend_address_pool {
    count = "${var.deployInfo["enableExtraServers"] == "true" ? 1 : 0}"
    name = "${var.extraServers["name"]}"
    ip_address_list = ["${var.extraServers["ip_address_list"]}"]
  }

  probe {
    count = "${var.deployInfo["enableExtraServers"] == "true" ? 1 : 0}"
    name = "${var.extraServers["name"]}"
    protocol = "Https"
    path = "${var.extraServers["healthCheckPath"]}"
    host = "127.0.0.1"
    interval  = 30
    timeout = 30
    unhealthy_threshold = 3
  }

  backend_http_settings {
    count = "${var.deployInfo["enableExtraServers"] == "true" ? 1 : 0}"
    name = "${var.extraServers["name"]}"
    cookie_based_affinity = "Disabled"
    port = 443
    protocol = "Https"
    request_timeout = 20
    probe_name = "${var.extraServers["name"]}"
    }
  }

  url_path_map {
    ...

    path_rule {
      count = "${var.deployInfo["enableExtraServers"] == "true" ? 1 : 0}"
      name = "${var.extraServers["name"]}"
      backend_address_pool_name = "${var.extraServers["name"]}"
      backend_http_settings_name = "${var.extraServers["name"]}"
      paths = ["/${var.extraServers["path"]}/*"]
    }
  }
}

References

[tombuildsstuff]

hi @PleaseStopAsking

Thanks for opening this issue :)

Whilst this isn't possible today using Terraform 0.11 - I believe this may be possible with some of the changes coming in Terraform 0.12 later this summer (although using lists/the for_each attribute on nested resources vs the count attribute). The other option we're looking into here is if we can split this resource out as we have for the Load Balancer resource to create multiple resources - the API doesn't currently allow for this however there's an issue tracking this Feature Request here after which time this may be possible.

It's worth noting that we're currently blocked on an upstream issue in the Azure API that means we're holding off on enhancements to the Application Gateway resource; we're tracking that on our side in #1576 which I'm going to close this in favour of to allow us to keep track of this in a single place.

Thanks!

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

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