multiregion-terraform

Example multi-region AWS Terraform application

TL;DR: launch 36 EC2 instances in 14 regions with a single terraform command

Amazon has 14 data centers with 38 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 >= v0.10.3
• override the Amazon credential profile settings by setting AWS_PROFILE=blah
• 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.

$ terraform output -module=cdn-us-east-1
servers = [
    54.198.56.163,
    52.90.73.117,
    52.91.127.142,
    52.207.230.71
]

$ 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 '[.modules[] | select(.outputs.servers.value != null) | .outputs.servers.value[] ]' terraform.tfstate
[
  "52.199.99.175",
  "52.193.39.37",
  "52.78.183.148",
  "52.78.230.74",
  "35.154.67.193",
  "35.154.47.136",
  "52.77.254.174",
  "52.221.244.90",
  "13.54.91.109",
  "13.54.35.0",
...
]