cfn-cheapest-nat

Cheapest AWS VPC NAT solution for personal projects.

Context

The current solutions is:

• EC2 running on Spot.
• Auto Healing
  • automatically replaces the unhealthy instance.
  • re-attaches a persistent network interface to recover transport level details such as routes.

The solution is not:

• Highly Available
  • instance unavailability will cause NAT disruption.
• Fault Tolerant
  • the persistent network interface results in dependency on a single zone.

Logical Diagram

Deploy

STACK_NAME=examples-nat \
PRIVATE_ROUTE_TABLES=rtb-0eee90cf29e333813,rtb-0c1d060b614e74b88 \
PUBLIC_SUBNET=subnet-03ad595bb28ce7679 \
  ./bin/deploy

Testing

I use the AWS System Manager Session Manager to SSH into an instance in a private subnet utilizing the NAT and run:

yum install python python-pip -y \
 && pip install --upgrade pip \
 && pip install speedtest-cli \
 && speedtest-cli
Retrieving speedtest.net configuration...
Testing from Amazon.com (54.206.26.162)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Telstra (Sydney) [1.01 km]: 1.82 ms
Testing download speed................................................................................
Download: 3283.42 Mbit/s
Testing upload speed................................................................................................
Upload: 2274.26 Mbit/s

Costs

solution	network	cost/GB	cost/hour**	cost/month**
NAT Gateway	5-45 Gbps	0.059	0.059	42.48
NAT Instance (t3a.nano)	0-5 Gbps	0-0.114	0.0059	4.25
NAT Instance (t3a.nano) (spot)	0-5 Gbps	0-0.114	0.0018*	1.30*

* variable costs.

** region ap-southeast-2.

AMI

Documentation

• VPC NAT Instance Documentation

Configuration

• /etc/sysctl.d/10-nat-settings.conf
• /usr/sbin/configure-pat.sh