Terraform Azure VNet with Dual Subnets and Route Tables

This Terraform project provisions a secure Azure Virtual Network (VNet) with two distinct subnets: 'internal' and 'external'. It creates corresponding route tables for each subnet to control traffic flow explicitly.

Features

• Creates a new Azure Resource Group or use existing.
• Deploys a Virtual Network (VNet) with a user-defined address space.
• Creates an internal subnet.
• Creates an external subnet.
• Sets default_outbound_access_enabled = false on both subnets. This is a security best practice, requiring explicit outbound access (e.g., via a NAT Gateway or firewall) rather than relying on Azure's default SNAT.
• Creates an internal route table (rt-internal) and associates it with the internal subnet. This table has no default routes, isolating it from the internet.
• Creates an external route table (rt-external) and associates it with the external subnet.
• Adds a default route (0.0.0.0/0) with a next hop of Internet to the external route table, allowing resources in this subnet to access the internet.

File Structure

• main.tf: Contains all the Azure resource definitions (VNet, Subnets, Route Tables, etc.).
• variables.tf: Declares all input variables used in the project.
• output.tf: Declares outputs from the created resources (e.g., VNet ID, subnet IDs).
• terraform.auto.tfvars: An example file to provide values for the variables.

Prerequisites

• Terraform (v1.0.0+)
• An Azure Subscription
• Azure CLI authenticated (or a Service Principal configured for Terraform).

How to Use

1. Clone the repository (or copy the files to a local directory).

2. Review and edit terraform.auto.tfvars: Update the values in this file to match your naming conventions and networking requirements.

   # --- Resource Group and Location ---
   resource_group_name = "my-networking-rg"
   location            = "West Europe"
   
   # --- Virtual Network ---
   vnet_name          = "main-vnet"
   vnet_address_space = ["10.61.0.0/16"]
   
   # --- Subnets ---
   internal_subnet = {
     name           = "snet-internal"
     address_prefix = "10.61.1.0/24"
   }
   
   external_subnet = {
     name           = "snet-external"
     address_prefix = "10.61.2.0/24"
   }
   
   # --- Route Tables ---
   internal_route_table_name = "rt-internal"
   external_route_table_name = "rt-external"
   

3. Initialize Terraform:

   terraform init
   

4. Review the plan:

   terraform plan
   

5. Apply the configuration:

   terraform apply
   

Inputs

Outputs