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
...
]