How to Manage Internal IP Addresses with Terraform

Terraform is a software toolkit designed for organizing infrastructure, including its creation and further management in the cloud. Its main advantage lies in automating all processes related to infrastructure deployment.

Private IP addresses are intended for organizing interaction between users within the same network. They are used to identify users who have connected to the network, as well as to grant them specific permissions for work.

In this guide, we will explain how Terraform can be used to set up private IP addresses and subsequently manage them. 

Creating Private IPs

Copy link

Step 1. Define Requirements

Copy link

First, compile a list of requirements for the future private IP addresses:

• Define the network zones and subnets where the future IP addresses will be placed;
• Specify the objects they will be used for (Virtual Machine, container, etc.);
• Select the provider that will be responsible for creating resources;
• Define the range of future IP addresses.

Step 2. Describe the Configuration

Copy link

Next, you need to write the code responsible for creating private IP addresses.

provider "provider_name" {
  project = "<project_name>"
  region  = "<region>"
}

resource "resource_name" "subnet_name" {
  name          = "subnet_name"
  ip_cidr_range = "IP_address_range"
  network       = "network_name"
}

resource "resource_name_for_private_ip" "private_ip_name" {
  name       = "private_ip_name"
  subnetwork = resource_name.subnet_name.self_link
}

Let’s break down the configuration to better understand it.

provider "provider_name" {
  project = "<project_name>"
  region  = "<region>"
}

Here we specify the provider name, project name, and region. All of these are required for creating future resources.

resource "resource_name" "subnet_name" {
  name          = "subnet_name"
  ip_cidr_range = "IP_address_range"
  network       = "network_name"
}

This part creates a subnet, which will later be used to assign resources. Here, you should specify the subnet name, IP address range, and the name of the network where the subnet will be created.

resource "resource_name_for_private_ip" "private_ip_name" {
  name       = "private_ip_name"
  subnetwork = resource_name.subnet_name.self_link
}

The last fragment is where we create the private IP address. It will be assigned within the subnet you set up in the previous fragment. The private IP address will fall within the range specified earlier.

We also use a reference to the self_link attribute (URI of the created resource) for the previously created subnet.

Step 3. Create Resources

Copy link

After writing the code, you can proceed to create the resource creation.

Run terraform plan to display which resources will be created. If everything is correct, run terraform apply to create the resources.

Managing Resources

Copy link

With Terraform, you can modify existing resources by editing your configuration.

If you need to edit, update, or delete private IP addresses you created, change the settings in the configuration file and run terraform plan to verify the settings.

If the configuration is valid, use terraform apply to implement the changes.

Using Modules in Terraform

Copy link

Modules allow you to organize containers for multiple resources at once, which will be used together. You can also call modules multiple times, enabling you to package resource configurations and reuse them.

The root module can call other child modules.

If you plan to create a large number of private IP addresses, you can use modules to reuse your code.

Using Variables in Configuration

Copy link

Variables allow you to customize aspects of Terraform modules without changing the module's source code. This feature enables modules to be shared across different Terraform configurations, making your module more modular and reusable.

The root module will contain only references to variables. All variable content will be in another module, which you can edit as needed. It is recommended to create a module named variables.tf for convenience.

Example of using variables to create private IP addresses:

provider "provider_name" {
  project = var.project_id
  region  = var.region
}

module "private_ip_address" {
  source          = "./modules/private-ip-address"
  subnetwork_name = var.subnetwork_name
  ip_cidr_range   = var.ip_cidr_range
  network_name    = var.network_name
  ip_address_name = var.ip_address_name
}

variable "project_id" {
  type        = string
  description = "Project identifier."
}

variable "region" {
  type        = string
  description = "Server region."
}

variable "subnetwork_name" {
  type        = string
  description = "Subnet name."
}

variable "ip_cidr_range" {
  type        = string
  description = "IP address range for the subnet."
}

variable "network_name" {
  type        = string
  description = "Network name."
}

variable "ip_address_name" {
  type        = string
  description = "private IP address name."
}

You also need to create a file containing the variable declarations.

Before making changes to the configuration, always check them using terraform plan. Only after that should you apply changes using terraform apply.

When creating new resources, always check which people and services are granted access. This applies not only to the process of creating private IP addresses.

In addition, you can use security scanning tools such as tfsec and Checkov. They can help detect potential vulnerabilities in your configuration.

Provide sufficient documentation for each resource and module you create, including leaving comments in the code. This will help you easily understand what is happening in your infrastructure and quickly resolve issues.

Conclusion

Copy link

In this guide, we have described in detail the process of creating and managing private IP addresses in Terraform, as well as provided additional tips for improving your configuration.