Estimate Terraform Costs

estimate-costs.sh

#!/usr/bin/env bash

# Runs https://github.com/antonbabenko/terraform-cost-estimation with sanitization
#
# Depends on:
#   - terraform cli >= 0.12
#   - curl
#   - jq >= 1.6

set -eo pipefail

function help {
	echo "usage: $0 [MODE] [TERRAFORM-DIRECTORY]"
	echo ""
	echo "  Mode (how to estimate costs)"
	echo "    plan - estimates the cost before a deployment"
	echo "    state - estimates the cost after a deployment"
}

MODE="state"
if [[ -n "$1" ]]
then
	if [[ "$1" == "plan" || "$1" == "state" ]]
	then
		MODE="$1"
	else
		echo "Could not find mode with name '$1'"
		help
		exit 1
	fi
fi

TERRAFORM_DIRECTORY="$(pwd)"
if [[ -n "$2" ]]
then
	if [[ -d "$2" ]]
	then
		TERRAFORM_DIRECTORY="$2"
	else
		echo "Could not find directory with path '$2'"
		help
		exit 1
	fi
fi

SCRIPT_DIRECTORY="$( cd "$( dirname "$0" )" && pwd )"

WORKDIR="$(mktemp -t -d estimate-costs-XXXXXX)"
TFPLAN="${WORKDIR}/plan.tfplan"
TFPLAN_JSON="${WORKDIR}/plan.json"
TFPLAN_JSON_SANITIZED="${WORKDIR}/plan-sanitized.json"

SANITIZATION_SCRIPT="${SCRIPT_DIRECTORY}/terraform.jq"

trap cleanup EXIT
cleanup() {
	rm -rf ${WORKDIR}
}

if [ ! -f "${SANITIZATION_SCRIPT}" ]
then
	echo "Downloading terraform sanitization script..."
	SANITIZATION_SCRIPT="${WORKDIR}/terraform.jq"
	curl -fsSL https://raw.githubusercontent.com/antonbabenko/terraform-cost-estimation/master/terraform.jq -o "${SANITIZATION_SCRIPT}"
fi

if [ "${MODE}" == "plan" ]
then
	terraform -chdir="${TERRAFORM_DIRECTORY}" plan -out="${TFPLAN}" > /dev/null
	terraform -chdir="${TERRAFORM_DIRECTORY}" show -json "${TFPLAN}" | jq > "${TFPLAN_JSON}"
elif [ "${MODE}" == "state" ]
then
	terraform -chdir="${TERRAFORM_DIRECTORY}" state pull | jq > "${TFPLAN_JSON}"
else
	echo "Could not find mode with name '$MODE'"
	help
	exit 1
fi

# Sanitize plan
cat "${TFPLAN_JSON}" | jq -cf ${SANITIZATION_SCRIPT} > "${TFPLAN_JSON_SANITIZED}"

# Check costs
cat "${TFPLAN_JSON_SANITIZED}" | curl -s -X POST -H "Content-Type: application/json" -d @- https://cost.modules.tf/