# chime/terraform-aws-alternat

High availability implementation of AWS NAT instances.

Repository: https://github.com/chime/terraform-aws-alternat
Canonical: https://ross.abutalabs.com/products/terraform-aws-alternat
Language: HCL
License: MIT
License Family: permissive
Topics: aws
Last push: 2026-04-16T20:47:25+00:00

## Health v2 (maintenance only)
Score: 76/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 77, release rhythm 60, longevity 100
- inputs: {"age_days": 1468, "days_push": 139, "days_rel": 264, "gap_med": 13, "n_releases_24m": 18}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1261, forks 94 (observed 2026-08-28T04:04:10.214931+00:00)

## What it is
A Terraform module that deploys highly available NAT instances on AWS as a cost-effective alternative to NAT Gateways. It automates EC2-based NAT with automatic route recovery and failover across availability zones.

## Use cases
- reduce AWS NAT Gateway data processing costs
- set up high availability NAT instances in a VPC
- replace NAT gateways with EC2 NAT instances via Terraform
- automatically recover NAT instance routes after failures
- cut egress networking costs for high-traffic private subnets

## When to choose
- NAT Gateway data processing charges are a significant part of your AWS bill
- you want infrastructure-as-code, self-healing NAT instances across multiple AZs
- your traffic volumes are high enough that EC2 instances are cheaper than managed NAT

## When to avoid
- you prefer a fully managed solution with no EC2 instances to maintain
- your traffic volume is low enough that NAT Gateway pricing is negligible
- you need NAT features like built-in high bandwidth or CloudWatch metrics without operational overhead

## Facets
- artifact type: infra-config
- maturity: active
- function: infrastructure-as-code, networking, cloud, deployment
- domain: cloud-computing, infrastructure-as-code, networking
- platform: cloud
- tags: nat-instance, high-availability, aws-vpc, cost-optimization, terraform-module, ec2, devops, terraform, linux

## Member repositories
- chime/terraform-aws-alternat (main) score 76

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:10.214931+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T05:04:18.033863+00:00, confidence not recorded.
  - readme: https://github.com/chime/terraform-aws-alternat (fetched 2026-08-28T04:04:10.214931+00:00, sha 5f918d347b37)
- Data as of 2026-08-30T08:39:29.467469+00:00.