AWS NAT Instance

Overview

Features

• Autoscaling group that spreads nat instances across the AWS region
• Spot instance support
• Optional Elastic IP

Usage

module "nat_instance" {
  source              = "github.com/htec-infra/terraform-aws-nat-instance"
  environment         = "Development"
  name                = "Test"
  namespace           = "PoC"
  vpc_id              = "vpc-123456"
  public_subnets      = ["subnet-123456789"]
  allocate_elastic_ip = true
}

Requirements

Name	Version
terraform	>= 0.13
aws	~> 3.0

Providers

Name	Version
aws	~> 3.0
template	n/a

Modules

Name	Source	Version
net_interface	./modules/net-interface

Resources

Name	Type
aws_autoscaling_group.this	resource
aws_iam_instance_profile.this	resource
aws_iam_role.this	resource
aws_iam_role_policy.eni	resource
aws_iam_role_policy_attachment.ssm	resource
aws_launch_template.this	resource
aws_security_group.this	resource
aws_ami.this	data source
aws_iam_policy_document.ec2_assume_role	data source
aws_iam_policy_document.eni	data source
aws_route_tables.private	data source
aws_vpc.this	data source
template_cloudinit_config.user_data	data source

Inputs

Name	Description	Type	Default	Required
add_db_subnet_route	Whether the DB subnet should have a route to the NAT Instance ENI	bool	false	no
allocate_elastic_ip	n/a	bool	false	no
enabled	Enable or not costly resources	bool	true	no
environment	Environment	string	n/a	yes
health_check_grace_period	How long ASG should wait before a health-check starts	number	180	no
image_id	AMI of the NAT instance. Default to the latest Amazon Linux 2	string	""	no
instance_types	Candidates of spot instance type for the NAT instance. This is used in the mixed instances policy	list(string)	[ "t3a.nano", "t3.nano" ]	no
key_name	Name of the key pair for the NAT instance. You can set this to assign the key pair to the NAT instance	string	""	no
name	Name for all the resources as identifier	string	n/a	yes
namespace	Module namespace	string	n/a	yes
public_subnets	IDs of the public subnets to place the NAT instance	list(string)	n/a	yes
tags	Tags applied to resources created with this module	map(string)	{}	no
use_spot_instance	Whether to use spot or on-demand EC2 instance	bool	true	no
vpc_id	ID of the VPC	string	n/a	yes

Outputs

Name	Description
iam_role_name	Name of the IAM role for the NAT instance
sg_id	ID of the security group of the NAT instance

Development

Prerequisites

• terraform
• terraform-docs
• pre-commit
• golang

Configurations

• Configure pre-commit hooks

pre-commit install

Tests

• Tests are available in test directory
• In the test directory, run the below command

go test