Terraform crashed- for azure_application_gateway while using dynamic for inside properties

[ghost]

This issue was originally opened by @samitkumarpatel as hashicorp/terraform#24315. It was migrated here as a result of the provider split. The original body of the issue is below.

---

Terraform Version

Terraform v0.12.14
+ provider.azurerm v2.0.0

Terraform Configuration Files

resource "azurerm_public_ip" "network" {
  name                = "pip01"
  resource_group_name = azurerm_resource_group.example.name
  location            = azurerm_resource_group.example.location
  allocation_method   = "Dynamic"
}

variable "gateway_config" {
  type = list
  default = [
    {
      gwPublicIpName            = "nginxPublicIp"
      gwFrontendHttpPortName    = "nginxFEPort80"
      gwFrontendIpName          = "nginxFEIpip"
      gwBackendPoolName         = "nginxBEPool"
      gwBackendHttpPortName     = "nginxBEhttpPort80"
      gatewayListnerName        = "nginxListner"
      gatewayRuleName           = "nginxRule"
    },
    {
      gwPublicIpName            = "jeninsPublicIp"
      gwFrontendHttpPortName    = "jenkinsFEPort8080"
      gwFrontendIpName          = "jenkinsFEIpip"
      gwBackendPoolName         = "jenkinsBEPool"
      gwBackendHttpPortName     = "jenkinsBEhttpPort8080"
      gatewayListnerName        = "jenkinsListner"
      gatewayRuleName           = "jenkinsRule"
    }
  ]
}

resource "azurerm_application_gateway" "example" {
  name                = "ag01"
  resource_group_name = azurerm_resource_group.example.name
  location            = azurerm_resource_group.example.location

  sku {
    name     = "Standard_Small"
    tier     = "Standard"
    capacity = 2
  }
  
  dynamic "gateway_ip_configuration" {
    for_each = [for s in var.gateway_config: {
        name      = s.gwPublicIpName
        subnet_id = element(tolist(azurerm_virtual_network.example.subnet),0).id
    }]

    content {
      name          = gateway_ip_configuration.value.name
      subnet_id     = gateway_ip_configuration.value.subnet_id
    }
  }
  
  dynamic "frontend_port" {
      for_each  =  [ for s in var.gateway_config: {
        name = s.gwFrontendHttpPortName
        port = 80
      }]
      content {
        name = frontend_port.value.name
        port = frontend_port.value.port
      }
  }
  
  dynamic "frontend_ip_configuration" {
      for_each  =  [ for s in var.gateway_config: {
        name                 = s.gwFrontendIpName
        public_ip_address_id = azurerm_public_ip.network.id
      }]
      content {
        name                 = frontend_ip_configuration.value.name
        public_ip_address_id = frontend_ip_configuration.value.public_ip_address_id
      }
  }
  
  dynamic "backend_address_pool" {
      for_each  =  [ for s in var.gateway_config: {
        name          = s.gwBackendPoolName
        #ip_addresses = []
      }]
      content {
        name          = backend_address_pool.value.name
        #ip_addresses = backend_address_pool.value.ip_addresses
      }
  }

  dynamic "backend_http_settings" {
      for_each  =  [ for s in var.gateway_config: {
        name                  = s.gwBackendHttpPortName
        cookie_based_affinity = "Disabled"
        port                  = 80
        protocol              = "Http"
        request_timeout       = 1
      }]
      content {
        name                  = backend_http_settings.value.name
        cookie_based_affinity = backend_http_settings.value.cookie_based_affinity
        port                  = backend_http_settings.value.port
        protocol              = backend_http_settings.value.protocol
        request_timeout       = backend_http_settings.value.request_timeout
      }
  }

  dynamic "http_listener" {
      for_each  =  [ for s in var.gateway_config: {
        name                           = s.gatewayListnerName
        frontend_ip_configuration_name = s.gwFrontendIpName
        frontend_port_name             = s.gwFrontendHttpPortName
        protocol                       = "Http"
      }]
      content {
        name                           = http_listener.value.name
        frontend_ip_configuration_name = http_listener.value.frontend_ip_configuration_name
        frontend_port_name             = http_listener.value.frontend_port_name
        protocol                       = http_listener.value.protocol
      }
  }

  dynamic "request_routing_rule" {
      for_each  =  [ for s in var.gateway_config: {
        name                       = s.gatewayRuleName
        rule_type                  = "Basic"
        http_listener_name         = s.gatewayListnerName
        backend_address_pool_name  = s.gwBackendPoolName
        backend_http_settings_name = s.gwBackendHttpPortName
      }]
      content {
        name                       = request_routing_rule.value.name
        rule_type                  = request_routing_rule.value.rule_type
        http_listener_name         = request_routing_rule.value.http_listener_name
        backend_address_pool_name  = request_routing_rule.value.backend_address_pool_name
        backend_http_settings_name = request_routing_rule.value.backend_http_settings_name
      }
  }
  
  tags  =   azurerm_resource_group.example.tags
}

Debug Output

Crash Output

attached
crash.log

Expected Behavior

Should create the application gateway with configuration

Actual Behavior

ERROR

Steps to Reproduce

Just run the hcl sysntex

[ghost]

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