How to use terraform to quickly deploy a decent Azure network

While I still #heart Pulumi, I still come across terraform in most engagements with customers. Here, I want to give you a quick way of deploying a decent “Getting started” virtual network that will allow you to test many different scenarios and keep iterating easily.
Deploying this code will cost you a little bit, due to the VPN Gateway (to support P2S or S2S VPN). You can easily comment that out though.
I know you just want to see the code, so if you do not want to read the rest, just hop over to https://github.com/davidobrien1985/decent-azure-vnet and see for yourself.

Deploying the infrastructure with terraform

Still here? Cool. What will you get when you deployed this code?

• an Azure virtual network
• multiple subnets, defined in the root’s variables.tf
• multiple private DNS zones to support a multitude of private endpoint scenarios
• a VPN Gateway deployed into the GatewaySubnet
• a Log Analytics workspace
• an Application Insights instance

You will find parameterised modules, the use of for_each concepts around terraform maps and lists, lookups of data and some other terraform things.

How to deploy with terraform

In the repo you will find an install-terraform.sh file you can execute and it will install terraform version 1.3.7. That file is not by me, I found it in one of my many random repos locally. If you wrote it, let me know and I’ll send you some money for a coffee as thanks.
I use WSL on Windows 11 for this kind of work, so bash was very handy for me.
Terraform is configured to use a local backend, so really all you need to do is:

• ./terraform/install-terraform.sh - install terraform. Make sure you reload your shell.
• cd infra/foundations
• terraform init - initialise the terraform backend / code
• az login - log in to your Azure subscription
• terraform plan - see what will happen if you were to deploy this
• terraform apply - this will actually apply the code

Do not want the resources anymore? terraform destroy will remove all those resources for you.

Making updates or changes to terraform

Want more or different subnets? Have a look at infra/foundations/variables.tf

variable "subnet" {
  description = "Map of Azure VNET subnet configuration"
  type        = map(any)
  default = {
    bastion_subnet = {
      name                 = "AzureBastionSubnet"
      address_prefixes     = ["10.0.1.0/26"]
    },
    gateway_subnet = {
      name                 = "GatewaySubnet"
      address_prefixes     = ["10.0.1.64/26"]
    }
    appgateway_subnet = {
      name                 = "ApplicationGatewaySubnet"
      address_prefixes     = ["10.0.2.0/26"]
    }
    forensicregisterapi_subnet = {
      name                 = "app"
      address_prefixes     = ["10.0.3.0/27"]
    }
    data_subnet = {
      name                 = "data"
      address_prefixes     = ["10.0.3.32/27"]
    }
  }
}

Change CIDR, add or remove subnets. Easy. This will be picked up next time you run the steps above.
Want to make changes or add other resources? Feel free to create a Pull Request on the repo and I will merge your resources / modules in to the repo.