Validate CloudFormation during build

validate-cloudformation.sh

#!/bin/bash

# Add this script to your cloudformation directory (we have ours in the project root).
# Then set up a build step in Team City that executes the custom script:
#
# [[ -f ./cloudformation/validate-cloudformation.sh ]] && ./cloudformation/validate-cloudformation.sh
#
# That way branches without the script will still build.
#
# Make sure your CI user has the following policy attached to it for AWS:
# {
#    "Version": "2012-10-17",
#    "Statement": [
#        {
#            "Effect": "Allow",
#            "Action": [
#                "cloudformation:ValidateTemplate"
#            ],
#            "Resource": "*"
#        }
#    ]
#}
#

CLOUDFORMATION_DIRECTORY="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

which aws 1>/dev/null 2>&1
if [[ $? -gt 0 ]]; then
	echo "AWS CLI not installed. Cannot validate Cloudformation Templates."
	exit 1
fi

if [[ -d "${CLOUDFORMATION_DIRECTORY}" ]]; then
	for TEMPLATE in $(find ${CLOUDFORMATION_DIRECTORY} -iname "*.json"); do
		echo -n "Validating CloudFormation template ${TEMPLATE}..."
		aws cloudformation validate-template --template-body "file://${TEMPLATE}" 1>/dev/null
		if [[ $? -gt 0 ]]; then
			exit 1
		fi
		echo " OK"
	done
fi

Nice one @nlindblad!