Terraform

Terraform ↗ is an infrastructure as code tool that lets you define and manage your tunnels alongside other infrastructure. This guide deploys:

• A GCP virtual machine that runs a web server
• A Cloudflare Tunnel that makes the server available over the Internet
• (Optional) A Cloudflare Access policy that defines who can connect

• A Google Cloud Project ↗
• A zone on Cloudflare

Refer to the Terraform installation guide ↗ for your operating system.

1. Install the gcloud CLI ↗ so that Terraform can interact with your GCP account.

2. Authenticate with the CLI by running:

   gcloud auth application-default login

Create an API token so that Terraform can interact with your Cloudflare account. At minimum, your token should include the following permissions:

Terraform functions through a working directory that contains configuration files. You can store your configuration in multiple files or just one — Terraform will evaluate all of the configuration files in the directory as if they were in a single document.

1. Create a folder for your Terraform configuration:

   mkdir cloudflare-tf

2. Change into the directory:

   cd cloudflare-tf

The following variables will be passed into your GCP and Cloudflare configuration.

1. In your configuration directory, create a .tf file:

   touch variables.tf

2. Open the file in a text editor and copy and paste the following:

   # GCP variables
   variable "gcp_project_id" {
     description = "Google Cloud Platform (GCP) project ID"
     type        = string
   }
   
   variable "zone" {
     description = "Geographical zone for the GCP VM instance"
     type        = string
   }
   
   variable "machine_type" {
     description = "Machine type for the GCP VM instance"
     type        = string
   }
   
   # Cloudflare variables
   variable "cloudflare_zone" {
     description = "Domain used to expose the GCP VM instance to the Internet"
     type        = string
   }
   
   variable "cloudflare_zone_id" {
     description = "Zone ID for your domain"
     type        = string
   }
   
   variable "cloudflare_account_id" {
     description = "Account ID for your Cloudflare account"
     type        = string
     sensitive   = true
   }
   
   variable "cloudflare_email" {
     description = "Email address for your Cloudflare account"
     type        = string
     sensitive   = true
   }
   
   variable "cloudflare_token" {
     description = "Cloudflare API token"
     type        = string
     sensitive   = true
   }

1. In your configuration directory, create a .tfvars file:

   touch terraform.tfvars

   Terraform will automatically use these variables if the file is named terraform.tfvars, otherwise the variable file will need to be manually passed in.

2. Add the following variables to terraform.tfvars. Be sure to modify the example with your own values.

   cloudflare_zone           = "example.com"
   cloudflare_zone_id        = "023e105f4ecef8ad9ca31a8372d0c353"
   cloudflare_account_id     = "372e67954025e0ba6aaa6d586b9e0b59"
   cloudflare_email          = "user@example.com"
   cloudflare_token          = "y3AalHS_E7Vabk3c3lX950F90_Xl7YtjSlzyFn_X"
   gcp_project_id            = "testvm-123"
   zone                      = "us-central1-a"
   machine_type              = "e2-medium"

You will need to declare the providers ↗ used to provision the infrastructure.

1. In your configuration directory, create a .tf file:

   touch providers.tf

2. Add the following providers to providers.tf. The random provider is used to generate a tunnel secret.

   terraform {
   	required_providers {
   		cloudflare = {
   			source = "cloudflare/cloudflare"
   			version = ">= 5.8.2"
   		}
   		google = {
   			source = "hashicorp/google"
   		}
   	}
   	required_version = ">= 1.2"
   }
   
   # Providers
   provider "cloudflare" {
   	api_token    = var.cloudflare_token
   }
   provider "google" {
   	project    = var.gcp_project_id
   }
   provider "random" {
   }

   terraform {
   	required_providers {
   		cloudflare = {
   			source = "cloudflare/cloudflare"
   			version = ">= 4.40.0, < 5.0.0"
   		}
   		google = {
   			source = "hashicorp/google"
   		}
   		random = {
   			source = "hashicorp/random"
   		}
   	}
   	required_version = ">= 1.2"
   }
   
   # Providers
   provider "cloudflare" {
   	api_token    = var.cloudflare_token
   }
   provider "google" {
   	project    = var.gcp_project_id
   }
   provider "random" {
   }

The following configuration will modify settings in your Cloudflare account.

1. In your configuration directory, create a .tf file:

   touch Cloudflare-config.tf

2. Add the following resources to Cloudflare-config.tf:

   
   # Creates a new remotely-managed tunnel for the GCP VM.
   resource "cloudflare_zero_trust_tunnel_cloudflared" "gcp_tunnel" {
   	account_id    = var.cloudflare_account_id
   	name          = "Terraform GCP tunnel"
   	config_src    = "cloudflare"
   }
   
   # Reads the token used to run the tunnel on the server.
   data "cloudflare_zero_trust_tunnel_cloudflared_token" "gcp_tunnel_token" {
   	account_id 	= var.cloudflare_account_id
   	tunnel_id 	= cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.id
   }
   
   # Creates the CNAME record that routes http_app.${var.cloudflare_zone} to the tunnel.
   resource "cloudflare_dns_record" "http_app" {
   	zone_id = var.cloudflare_zone_id
   	name    = "http_app"
   	content = "${cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.id}.cfargotunnel.com"
   	type    = "CNAME"
   	ttl     = 1
   	proxied = true
   }
   
   # Configures tunnel with a published application for clientless access.
   resource "cloudflare_zero_trust_tunnel_cloudflared_config" "gcp_tunnel_config" {
   	tunnel_id  = cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.id
   	account_id = var.cloudflare_account_id
   	config     = {
   		ingress 	= [
   			{
   				hostname = "http_app.${var.cloudflare_zone}"
   				service  = "http://httpbin:80"
   			},
   			{
   				service  = "http_status:404"
   			}
   		]
   	}
   }
   
   # (Optional) Routes internal IP of GCP instance through the tunnel for private network access using WARP.
   resource "cloudflare_zero_trust_tunnel_cloudflared_route" "example_tunnel_route" {
   account_id         = var.cloudflare_account_id
   tunnel_id          = cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.id
   network            = google_compute_instance.http_server.network_interface.0.network_ip
   comment            = "Example tunnel route"
   }
   
   # Creates a reusable Access policy.
   resource "cloudflare_zero_trust_access_policy" "allow_emails" {
   	account_id   = var.cloudflare_account_id
   	name         = "Allow email addresses"
   	decision     = "allow"
   	include      = [
   		{
   			email = {
   				email = var.cloudflare_email
   			}
   		},
   		{
   			email_domain = {
   				domain = "@example.com"
   			}
   		}
   	]
   }
   
   # Creates an Access application to control who can connect to the public hostname.
   resource "cloudflare_zero_trust_access_application" "http_app" {
   	account_id       = var.cloudflare_account_id
   	type             = "self_hosted"
   	name             = "Access application for http_app.${var.cloudflare_zone}"
   	domain           = "http_app.${var.cloudflare_zone}"
   	policies = [
   		{
   			id = cloudflare_zero_trust_access_policy.allow_emails.id
   			precedence = 1
   		}
   	]
   }

   # Generates a 32-byte secret for the tunnel.
   resource "random_bytes" "tunnel_secret" {
   	byte_length = 32
   }
   
   # Creates a new remotely-managed tunnel for the GCP VM.
   resource "cloudflare_zero_trust_tunnel_cloudflared" "gcp_tunnel" {
   	account_id = var.cloudflare_account_id
   	name       = "Terraform GCP tunnel"
   	secret     = random_bytes.tunnel_secret.base64
   }
   
   # Creates the CNAME record that routes http_app.${var.cloudflare_zone} to the tunnel.
   resource "cloudflare_record" "http_app" {
   	zone_id = var.cloudflare_zone_id
   	name    = "http_app"
   	content   = "${cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.cname}"
   	type    = "CNAME"
   	proxied = true
   }
   
   # Configures tunnel with a published application for clientless access.
   resource "cloudflare_zero_trust_tunnel_cloudflared_config" "gcp_tunnel_config" {
   	tunnel_id = cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.id
   	account_id = var.cloudflare_account_id
   	config {
   		ingress_rule {
   			hostname = "${cloudflare_record.http_app.hostname}"
   			service  = "http://httpbin:80"
   		}
   		ingress_rule {
   			service  = "http_status:404"
   		}
   	}
   }
   
   # (Optional) Route internal IP of GCP instance through the tunnel for private network access using WARP.
   resource "cloudflare_zero_trust_tunnel_route" "example_tunnel_route" {
   account_id         = var.cloudflare_account_id
   tunnel_id          = cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.id
   network            = google_compute_instance.http_server.network_interface.0.network_ip
   comment            = "Example tunnel route"
   }
   
   # Creates an Access application to control who can connect to the public hostname.
   resource "cloudflare_zero_trust_access_application" "http_app" {
   	account_id          = var.cloudflare_account_id
   	name             = "Access application for http_app.${var.cloudflare_zone}"
   	domain           = "http_app.${var.cloudflare_zone}"
   }
   
   # Creates a (legacy) Access policy for the Access application.
   resource "cloudflare_zero_trust_access_policy" "allow_emails" {
   	application_id = cloudflare_zero_trust_access_application.http_app.id
   	account_id        = var.cloudflare_account_id
   	name           = "Example policy for http_app.${var.cloudflare_zone}"
   	precedence     = "1"
   	decision       = "allow"
   	include {
   		email = [var.cloudflare_email]
   	}
   }

To learn more about these resources, refer to the Cloudflare provider documentation ↗.

The following configuration defines the specifications for the GCP virtual machine and configures a startup script to run upon boot.

1. In your configuration directory, create a .tf file:

   touch GCP-config.tf

2. Add the following content to GCP-config.tf:

   # OS the server will use
   data "google_compute_image" "image" {
   	family  = "ubuntu-2204-lts"
   	project = "ubuntu-os-cloud"
   }
   
   # GCP Instance resource
   resource "google_compute_instance" "http_server" {
   	name         = "test"
   	machine_type = var.machine_type
   	zone         = var.zone
   	tags         = []
   	boot_disk {
   		initialize_params {
   			image = data.google_compute_image.image.self_link
   		}
   	}
   
   	network_interface {
   		network = "default"
   		access_config {
   			//Ephemeral IP
   		}
   	}
   	// Optional config to make instance ephemeral
   /*  scheduling {
   		preemptible       = true
   		automatic_restart = false
   	} */
   
   	// Pass the tunnel token to the GCP server so that the server can install and run the tunnel upon startup.
   	metadata_startup_script = templatefile("./install-tunnel.tftpl",
   		{
   			tunnel_token = data.cloudflare_zero_trust_tunnel_cloudflared_token.gcp_tunnel_token.token
   		})
   }

   # OS the server will use
   data "google_compute_image" "image" {
   	family  = "ubuntu-2204-lts"
   	project = "ubuntu-os-cloud"
   }
   
   # GCP Instance resource
   resource "google_compute_instance" "http_server" {
   	name         = "test"
   	machine_type = var.machine_type
   	zone         = var.zone
   	tags         = []
   	boot_disk {
   		initialize_params {
   			image = data.google_compute_image.image.self_link
   		}
   	}
   
   	network_interface {
   		network = "default"
   		access_config {
   			//Ephemeral IP
   		}
   	}
   	// Optional config to make instance ephemeral
   /*  scheduling {
   		preemptible       = true
   		automatic_restart = false
   	} */
   
   	// Pass the tunnel token to the GCP server so that the server can install and run the tunnel upon startup.
   	metadata_startup_script = templatefile("./install-tunnel.tftpl",
   		{
   			tunnel_token = cloudflare_zero_trust_tunnel_cloudflared.gcp_tunnel.tunnel_token
   		})
   }

The following script will install cloudflared and run the tunnel as a service. This example also installs a lightweight HTTP application that you can use to test connectivity.

1. In your configuration directory, create a Terraform template file:

   touch install-tunnel.tftpl

2. Open the file in a text editor and copy and paste the following bash script:

   # Script to install Cloudflare Tunnel and Docker resources
   
   # Docker configuration
   cd /tmp
   sudo apt-get install software-properties-common
   # Retrieving the docker repository for this OS
   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
   sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable"
   # The OS is updated and docker is installed
   sudo apt update -y && sudo apt upgrade -y
   sudo apt install docker docker-compose -y
   # Add the HTTPBin application and run it on localhost:8080.
   cat > /tmp/docker-compose.yml << "EOF"
   version: '3'
   services:
     httpbin:
       image: kennethreitz/httpbin
       restart: always
       container_name: httpbin
       ports:
         - 8080:80
   
     cloudflared:
       image: cloudflare/cloudflared:latest
       restart: always
       container_name: cloudflared
       command: tunnel run --token ${tunnel_token}
   EOF
   cd /tmp
   sudo docker-compose up -d

To deploy the configuration files:

1. Initialize your configuration directory:

   terraform init

2. Preview everything that will be created:

   terraform plan

3. Apply the configuration:

   terraform apply

It may take several minutes for the GCP instance and tunnel to come online. You can view your new tunnel in the Cloudflare dashboard ↗ under Networking > Tunnels.

1. In the Cloudflare dashboard ↗, go to Networking > Tunnels and verify that your tunnel is Active.

2. (Optional) If you configured Access, go to Security > Access > Applications and verify that your Cloudflare email is allowed by the Access policy.

3. From any device, open a browser and go to http_app.<CLOUDFLARE_ZONE> (for example, http_app.example.com).

   If you configured Access, you will see the Access login page. Log in with your Cloudflare email.

4. You should see the HTTPBin homepage, confirming that your tunnel is routing traffic correctly.