README.md

Terraform fck-nat

Introduction

A Terraform module for deploying NAT Instances using fck-nat. The (f)easible (c)ost (k)onfigurable NAT! The following is a list of features available with this module:

• High-availability mode achieved through a floating internal ENI automatically attached to instances being started by an ASG
• Optional consistent static IP via EIP re-attachment to the internet facing ENI
• Cloudwatch metrics reported similar to those available with the managed NAT Gateway
• Use of spot instances instead of on-demand for reduced costs

Example

module "fck-nat" {
  source = "git::https://github.com/RaJiska/terraform-aws-fck-nat.git"

  name                 = "my-fck-nat"
  vpc_id               = "vpc-abc1234"
  subnet_id            = "subnet-abc1234"
  # ha_mode              = true                 # Enables high-availability mode
  # eip_allocation_ids   = ["eipalloc-abc1234"] # Allocation ID of an existing EIP
  # use_cloudwatch_agent = true                 # Enables Cloudwatch agent and have metrics reported

  update_route_tables = true
  route_tables_ids = {
    "your-rtb-name-A" = "rtb-abc1234Foo"
    "your-rtb-name-B" = "rtb-abc1234Bar"
  }
}

Requirements

Name	Version
terraform	~> 1.3
aws	>= 4.0

Providers

Name	Version
aws	>= 4.0

Resources

Name	Type
aws_autoscaling_group.main	resource
aws_iam_instance_profile.main	resource
aws_iam_policy.main	resource
aws_iam_role.main	resource
aws_iam_role_policy_attachment.main	resource
aws_instance.main	resource
aws_launch_template.main	resource
aws_network_interface.main	resource
aws_route.main	resource
aws_security_group.main	resource
aws_ssm_parameter.cloudwatch_agent_config	resource
aws_ami.main	data source
aws_arn.ssm_param	data source
aws_caller_identity.current	data source
aws_iam_policy_document.instance_assume_role_policy	data source
aws_iam_policy_document.main	data source
aws_region.current	data source
aws_vpc.main	data source

Inputs

Name	Description	Type	Default	Required
additional_security_group_ids	A list of identifiers of security groups to be added for the NAT instance	list(string)	[]	no
ami_id	AMI to use for the NAT instance. Uses fck-nat latest AMI in the region if none provided	string	null	no
attach_ssm_policy	Whether to attach the minimum required IAM permissions to connect to the instance via SSM.	bool	true	no
cloudwatch_agent_configuration	CloudWatch configuration for the NAT instance	object({ namespace = optional(string, "fck-nat"), collection_interval = optional(number, 60), endpoint_override = optional(string, "") })	{ "collection_interval": 60, "endpoint_override": "", "namespace": "fck-nat" }	no
cloudwatch_agent_configuration_param_arn	ARN of the SSM parameter containing the CloudWatch agent configuration. If none provided, creates one	string	null	no
ebs_root_volume_size	Size of the EBS root volume in GB	number	8	no
eip_allocation_ids	EIP allocation IDs to use for the NAT instance. Automatically assign a public IP if none is provided. Note: Currently only supports at most one EIP allocation.	list(string)	[]	no
encryption	Whether or not to encrypt the EBS volume	bool	true	no
ha_mode	Whether or not high-availability mode should be enabled via autoscaling group	bool	true	no
instance_type	Instance type to use for the NAT instance	string	"t4g.micro"	no
kms_key_id	Will use the provided KMS key ID to encrypt the EBS volume. Uses the default KMS key if none provided	string	null	no
name	Name used for resources created within the module	string	n/a	yes
route_table_id	Deprecated. Use route_tables_ids instead	string	null	no
route_tables_ids	Route tables to update. Only valid if update_route_tables is true	map(string)	{}	no
ssh_cidr_blocks	CIDR blocks to allow SSH access to the NAT instance from	object({ ipv4 = optional(list(string), []) ipv6 = optional(list(string), []) })	{ "ipv4": [], "ipv6": [] }	no
ssh_key_name	Name of the SSH key to use for the NAT instance. SSH access will be enabled only if a key name is provided	string	null	no
subnet_id	Subnet ID to deploy the NAT instance into	string	n/a	yes
tags	Tags to apply to resources created within the module	map(string)	{}	no
update_route_table	Deprecated. Use update_route_tables instead	bool	false	no
update_route_tables	Whether or not to update the route tables with the NAT instance	bool	false	no
use_cloudwatch_agent	Whether or not to enable CloudWatch agent for the NAT instance	bool	false	no
use_default_security_group	Whether or not to use the default security group for the NAT instance	bool	true	no
use_spot_instances	Whether or not to use spot instances for running the NAT instance	bool	false	no
use_ssh	Whether or not to enable SSH access to the NAT instance	bool	false	no
vpc_id	VPC ID to deploy the NAT instance into	string	n/a	yes

Outputs

Name	Description
ami_id	AMI to use for the NAT instance. Uses fck-nat latest arm64 AMI in the region if none provided
autoscaling_group_arn	The ARN of the autoscaling group if running in HA mode
cw_agent_config_ssm_parameter_arn	The ARN of the SSM parameter containing the Cloudwatch agent config
encryption	Whether or not fck-nat instance EBS volumes are encrypted
eni_arn	The ARN of the static ENI used by the fck-nat instance
eni_id	The ID of the static ENI used by the fck-nat instance
ha_mode	Whether or not high-availability mode is enabled via autoscaling group
instance_arn	The ARN of the fck-nat instance if running in non-HA mode
instance_profile_arn	The ARN of the instance profile used by the fck-nat instance
instance_public_ip	The public IP address of the fck-nat instance if running in non-HA mode
instance_type	Instance type used for the fck-nat instance
kms_key_id	KMS key ID to use for encrypting fck-nat instance EBS volumes
launch_template_id	The ID of the launch template used to spawn fck-nat instances
name	Name used for resources created within the module
role_arn	The ARN of the role used by the fck-nat instance profile
security_group_id	Deprecated. The ID of the security group used by fck-nat ENIs
security_group_ids	List of security group IDs used by fck-nat ENIs
subnet_id	Subnet ID to which the fck-nat instance is deployed into
vpc_id	VPC ID to which the fck-nat instance is deployed into