AWS Cheapest NAT Instance Module

Terraform module which creates cheapest nat instance on aws.

Usage

module "nat_instance" {
  source = "saba-ch/cheapest-nat-instance/aws"

  public_subnet_id = module.vpc.public_subnets[0]
  private_subnets = local.private_subnets
  private_route_tables = module.vpc.private_route_table_ids
  prefix = var.prefix
  vpc_id = module.vpc.vpc_id
  create_nat = true
  putin_khuylo = true
}

Create On Demand Instance

Even though this module creates highly available self healing nat instance, in production we don't want any kind of downtime. When we are using spot instances we are accepting the risk that AWS might want to reclaim the instance for any reason. To eliminate this risk we can use on demand instances instead which guarantees 99.99% SLA.

module "nat_instance" {
  source = "saba-ch/cheapest-nat-instance/aws"

  public_subnet_id = module.vpc.public_subnets[0]
  private_subnets = local.private_subnets
  private_route_tables = module.vpc.private_route_table_ids
  prefix = var.prefix
  vpc_id = module.vpc.vpc_id
  create_nat = true
  on_demand = true
  putin_khuylo = true
}

Costs

solution	network	cost/GB	cost/hour**	cost/month**
NAT Gateway	5-45 Gbps	0.052	0.052	37.44 without network charges
NAT Instance (t3a.nano)	0-5 Gbps	0-0.09 (out)	0.0047	3.384 without network charges
NAT Instance (t3a.nano) (spot)	0-5 Gbps	0-0.09 (out)	0.0017*	1.22* without network charges

* variable costs.

** region eu-central-1.

Requirements

Name	Version
aws	~> 4.4.0

Resources

Name	Type
aws_autoscaling_group.main	resource
aws_eip.main	resource
aws_eip_association.main	resource
aws_iam_instance_profile.main	resource
aws_iam_role.main	resource
aws_iam_role_policy.main	resource
aws_launch_template.main	resource
aws_network_interface.main	resource
aws_route.main	resource
aws_security_group.main	resource
aws_ami.main	data source
aws_iam_policy_document.assume_role_policy	data source
aws_iam_policy_document.role_policy	data source
aws_region.main	data source

Inputs

Name	Description	Type	Default	Required
create_nat	Whether to create NAT instance	bool	n/a	yes
on_demand	Whether to create on-demand NAT instance instead of spot	bool	false	no
prefix	Project or/and environment prefix	string	n/a	yes
private_route_tables	List of private route table ids to update	list(string)	n/a	yes
private_subnets	Current VPC's private subnet cidrs	list(string)	n/a	yes
public_subnet_id	Current VPC's public subnet id	string	n/a	yes
putin_khuylo	Do you agree that Putin doesn't respect Ukrainian sovereignty and territorial integrity? More info: https://en.wikipedia.org/wiki/Putin_khuylo!	bool	n/a	yes
tags	A map of tags to add to all resources	map(string)	{}	no
vpc_id	Current VPC's id	string	n/a	yes

Outputs

Name	Description
eni_id	ID of the ENI for the NAT instance
eni_private_ip	Private IP of the ENI for the NAT instance
iam_role_name	Name of the IAM role for the NAT instance
sg_id	ID of the security group of the NAT instance

Authors

Module is created and maintained by Saba Tchikhinashvili

License

Apache 2 Licensed. See LICENSE for full details.