In terraform tfvars file can we put value somewhere else and then simply we can just recall?

Can we put route table value somewhere else eg other tfvars file or varibles/local and then just in the tfvars file. we can call route table route_table =""

networks = {
  umms-security-vnet = {
    resource_group_name = "testrg" #required
    location            = "eastus"                      #required
    addressSpace = [
      "10.229.192.0/20" #required
    ]
    dnsServers = [
      "10.231.18.4",
      "146.189.24.10",
      "172.26.40.125"
    ]
    subnets = {
      GatewaySubnet = {
        addressPrefix = "10.229.192.0/24"
      }
      app-1-subnet = {
        addressPrefix                     = "10.229.198.0/24" #required
        route_table = {                                        #optional
          security-rt = {
            disableBgpRoutePropagation = false
            routes = [
              {
                name             = "default-udr"
                addressPrefix    = "0.0.0.0/0"
                nextHopType      = "VirtualAppliance"
                nextHopIpAddress = "10.231.10.100"
              },
              {
                name             = "network-146.189.0.0-16-udr"
                addressPrefix    = "146.189.0.0/16"
                nextHopType      = "VirtualAppliance"
                nextHopIpAddress = "10.231.10.200"
              }
            ]
          }
        }

Can we put route table value somewhere else eg other tfvars file or varibles/local and then just in the tfvars file. we can call route table route_table

Yes, you can store the value of the route table in variables instead of directly in the tfvars file. This allows you to define the route table value in variables and reference it in tfvars file.

Here is the updated Terraform code.

Main.tf

provider "azurerm" {
  features {}
}

resource "azurerm_resource_group" "vnetrg" {
  name     = "VNET-RG"
  location = "eastus"
}

resource "azurerm_virtual_network" "security-vnet" {
  name                = "security-vnet"
  address_space       = var.address_space
  location            = azurerm_resource_group.vnetrg.location
  resource_group_name = azurerm_resource_group.vnetrg.name
}

resource "azurerm_subnet" "subnet-without-rt" {
  name                 = "subnet-without-rt"
  address_prefixes     = [var.subnet_prefixes[0]]
  virtual_network_name = azurerm_virtual_network.security-vnet.name
  resource_group_name  = azurerm_resource_group.vnetrg.name
}

resource "azurerm_subnet" "subnet-with-rt" {
  name                 = "subnet-with-rt"
  address_prefixes     = [var.subnet_prefixes[1]]
  virtual_network_name = azurerm_virtual_network.security-vnet.name
  resource_group_name  = azurerm_resource_group.vnetrg.name
}

resource "azurerm_subnet_route_table_association" "subnet-with-rt-association" {
  subnet_id      = azurerm_subnet.subnet-with-rt.id
  route_table_id = azurerm_route_table.security-rt.id
}

resource "azurerm_route_table" "security-rt" {
  name                = "security-rt"
  location            = azurerm_resource_group.vnetrg.location
  resource_group_name = azurerm_resource_group.vnetrg.name

  dynamic "route" {
    for_each = var.route_table["security-rt"].routes
    content {
      name             = route.value.name
      address_prefix   = route.value.addressPrefix
      next_hop_type    = route.value.nextHopType
      next_hop_in_ip_address = route.value.nextHopIpAddress
    }
  }
}

variables.tf

variable "address_space" {
  description = "Address space for the virtual network"
  type        = list(string)
}

variable "subnet_prefixes" {
  description = "Prefixes for the subnets"
  type        = list(string)
}
variable "route_table" {
  description = "Route table configuration"
  type        = map(object({
    disableBgpRoutePropagation = bool
    routes = list(object({
      name             = string
      addressPrefix    = string
      nextHopType      = string
      nextHopIpAddress = string
    }))
  }))
  default     = {
    security-rt = {
      disableBgpRoutePropagation = false
      routes = [
        {
          name             = "default-udr"
          addressPrefix    = "0.0.0.0/0"
          nextHopType      = "VirtualAppliance"
          nextHopIpAddress = "10.231.10.100"
        },
        {
          name             = "network-146.189.0.0-16-udr"
          addressPrefix    = "146.189.0.0/16"
          nextHopType      = "VirtualAppliance"
          nextHopIpAddress = "10.231.10.200"
        }
      ]
    }
  }
}

terraform.tfvars

address_space = ["10.229.192.0/20"]

subnet_prefixes = ["10.229.192.0/24", "10.229.198.0/24"]

route_table = {
  "security-rt" = {
    disableBgpRoutePropagation = false
    routes = [
      {
        name             = "default-udr"
        addressPrefix    = "0.0.0.0/0"
        nextHopType      = "VirtualAppliance"
        nextHopIpAddress = "10.231.10.100"
      },
      {
        name             = "network-146.189.0.0-16-udr"
        addressPrefix    = "146.189.0.0/16"
        nextHopType      = "VirtualAppliance"
        nextHopIpAddress = "10.231.10.200"
      }
    ]
  }
}

Theroute_table variable is defined in variables.tf block, and its value is referenced in the tfvars file using var.route_table["security-rt"].

Terraform Apply

Once the ran above Terraform code, the resources are created successfully as below.

Reference: azurestack_virtual_network