find-free-vpcs.sh

#!/bin/bash

# Dependencies: AWS CLI, GNU sort, bc
# Tested on Fedora 35.

# Requires valid AWS creds be available to the AWS CLI.

# Example usage: 

# find-free-vpcs.sh
# -- query all regions you have access to
# (this will be very slow as it has to make multiple queries for every AWS region)

# find-free-vpcs.sh "string"
# -- query only the regions that begin with a match to "string", e.g. "us" or "us-east"

# You can also use an egrep-compatible regex, e.g.:
# find-free-vpcs.sh 'us-east|eu-west'

REGION_LIST=$(aws --output text --no-paginate --query 'Regions[*].RegionName' ec2 describe-regions)
AWS_GEO=$1

OUTPUT=""

for region in $REGION_LIST; do
  if [[ ! -z $AWS_GEO && $(echo $region | grep -E ^$AWS_GEO) ]] || [[ -z $AWS_GEO ]]; then
    VPC_QUOTA=$(echo "scale=0; $(aws service-quotas list-service-quotas --output text --service-code vpc --query "Quotas[?QuotaName=='VPCs per Region'].Value" --region $region)/1" | bc)
    VPC_USAGE=$(aws ec2 describe-vpcs --output text --no-paginate --query 'length(Vpcs[].VpcId)' --region $region)
    VPC_QUOTA_FREE=$(echo "scale=0; ($VPC_QUOTA - $VPC_USAGE)/1" | bc)
    OUTPUT+="$region:\tQuota = $VPC_QUOTA\tUsed = $VPC_USAGE\tFree = $VPC_QUOTA_FREE\n"
  fi
done


echo -e "$OUTPUT" | sort -n -r -k 10