Terraform module: Delete default VPCs

Terraform itself does not have the capability to delete default VPCs. In this example, I will use terraform and a shell script to perform the deletion.

The delete-default-vpcs module

The module itself contains just 1 resource, which uses the local exec provisioner to execute a script

resource "null_resource" "shell" {
  provisioner "local-exec" {
    command = "/bin/bash -c '${path.module}/exec.sh ${var.region-name}'"
  }
}

The exec.sh uses aws-cli to delete the default VPC and dependent resources

#!/bin/bash

region=$1
vpc=$(aws ec2 --region ${region} describe-vpcs --filter Name=isDefault,Values=true | jq -r .Vpcs[0].VpcId)
if [ "${vpc}" = "null" ]; then
  echo "Default vpc not exist"
  exit 0
fi

aws ec2 --region ${region} describe-internet-gateways --filter Name=attachment.vpc-id,Values=${vpc} | jq -r '.InternetGateways[0].InternetGatewayId' | while read igw; do
  echo "Removing internet gateway ${igw}"
  aws ec2 --region ${region} detach-internet-gateway --internet-gateway-id ${igw} --vpc-id ${vpc}
  aws ec2 --region ${region} delete-internet-gateway --internet-gateway-id ${igw}
done

aws ec2 --region ${region} describe-subnets --filters Name=vpc-id,Values=${vpc} | jq -r '.Subnets[].SubnetId' | while read subnet; do
  echo "Removing subnet ${subnet}"
  aws ec2 --region ${region} delete-subnet --subnet-id ${subnet}
done

echo "Removing vpc ${vpc}"
aws ec2 --region ${region} delete-vpc --vpc-id ${vpc}

The root module

The root module calling the delete-default-vpcs module looks like this. It uses the aws_regions data source to query enabled regions, then provide it to the delete-default-vpcs module.

data "aws_regions" "current" {}

module delete-default-vpc {
  source = "./module/delete-default-vpc"
  for_each = data.aws_regions.current.names
  region-name = each.value
}