multiregion-terraform

Example multi-region AWS Terraform application

TL;DR: launch ~56 EC2 instances in 18 regions with a single terraform command

Amazon has 18 data centers with ~56 availability zones spread around the world. This Terraform application launches EC2 instances in every possible zone, and ties them together into a single domain name that routes pings to the closest instance.

Features

Single main.tf with a module instance for each Amazon's 14 regions
Creates an EC2 instance in every region and availability zone
Creates two Route 53 records (A and AAAA) with latency based routing to all EC2 instances
All instances allow ICMP Echo Request (ping) from 0.0.0.0/0
Supports IPv4 and IPv6

Latency Map

Note the lower latency when the ping source is near to one of Amazon's datacenters:

Terraform Dependency Graph

How-to

Notes:

IMPORTANT: edit cdn/variables.tf and set r53_zone_id and r53_domain_name
requires Terraform >= v0.12
override the Amazon credential profile settings by setting AWS_PROFILE=blah
optionaly update blacklisted_az with any availibility zones that might not support the instances types you want
comment out regions in main.tf to test a smaller deployment
Terraform types used: aws_ami, aws_vpc, aws_internet_gateway, aws_subnet, aws_route_table, aws_route_table_association, aws_security_group, aws_instance, and aws_route53_record

$ terraform init
...

# replace 'personal' with the name of your AWS profile in ~/.aws/crendentials or leave blank for 'default'
$ AWS_PROFILE=personal terraform plan
module.cdn-us-east-1.data.aws_ami.default: Refreshing state...
module.cdn-us-west-1.data.aws_ami.default: Refreshing state...
...
Plan: 32 to add, 0 to change, 0 to destroy.

$ AWS_PROFILE=personal terraform apply
module.cdn-us-west-1.data.aws_ami.default: Refreshing state...
module.cdn-us-east-1.data.aws_ami.default: Refreshing state...
...
Apply complete! Resources: 32 added, 0 changed, 0 destroyed.

$ dig +short @8.8.8.8 cdn.jonathan.camp
52.207.230.71
52.90.73.117
52.91.127.142
54.198.56.163

$ dig +short @8.8.8.8 cdn.jonathan.camp AAAA
2a05:d01c:f93:2701:c9ab:9b4d:c81:9f05
2a05:d01c:f93:2700:604a:53ae:33b8:24c0

# print all servers using jq (https://stedolan.github.io/jq/)
$ jq -r '[.resources[].instances[] | select(.attributes.public_ip != null) | .attributes.public_ip] | .[]' terraform.tfstate
18.230.154.45
54.233.83.81
18.231.187.164
15.206.28.49
15.206.88.49
3.7.58.137
...
]