Removes internet gateways and subnets from and then deletes all default VPCs in an AWS account.

delete-default-vpc-networks.sh

#!/usr/bin/env bash
set -euo pipefail

function error {
  >&2 printf "\033[31mERROR\033[0m: $@\n"
}

INIT_ERROR=
for DEP_NAME in aws-vault jq aws; do
  if ! which "${DEP_NAME}" 2>/dev/null >/dev/null; then
    error "Command '${DEP_NAME}' not found. Please install."
    INIT_ERROR=1
  fi
done
[[ ${INIT_ERROR} ]] && exit 1

for region in $(aws ec2 describe-regions | jq -r .Regions[].RegionName); do

  echo "==> Region ${region}"

  vpc=$(aws ec2 --region ${region} describe-vpcs --filter Name=isDefault,Values=true | jq -r .Vpcs[0].VpcId)
  if [ "${vpc}" = "null" ]; then
    echo "  - No default VPC found"
    continue
  fi
  echo "Found default VPC ${vpc}"

  igw=$(
    aws ec2 --region ${region} describe-internet-gateways --filter Name=attachment.vpc-id,Values=${vpc} \
      | jq -r .InternetGateways[0].InternetGatewayId
  )
  if [ "${igw}" != "null" ]; then
    echo "  - Detaching and deleting 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}
  fi

  subnets=$(aws ec2 --region ${region} describe-subnets --filters Name=vpc-id,Values=${vpc} | jq -r .Subnets[].SubnetId)
  if [ "${subnets}" != "null" ]; then
    for subnet in ${subnets}; do
      echo "  - Deleting subnet ${subnet}"
      aws ec2 --region ${region} delete-subnet --subnet-id ${subnet}
    done
  fi

  echo "  - Deleting default VPC ${vpc}"
  aws ec2 --region ${region} delete-vpc --vpc-id ${vpc}
done