gistfile1.txt

#!/usr/bin/env bash
set -o errexit
set -o nounset
set -o pipefail

CFN_FILE=file://$(pwd)/github_service_account.yaml
STACK='github-service-account'
REGION='us-east-1'

if ! (aws cloudformation describe-stacks --region ${REGION} --stack-name ${STACK}) ; then
    echo "Creating stack"
    aws cloudformation create-stack --stack-name ${STACK} --template-body ${CFN_FILE} --region ${REGION} --capabilities CAPABILITY_NAMED_IAM
    echo "Waiting for stack to be created ..."
    aws cloudformation wait stack-create-complete --stack-name ${STACK} --region ${REGION}

else

    echo "Stack exists, attempting to update."
    set +e
    update=$(aws cloudformation update-stack --stack-name ${STACK} --template-body $CFN_FILE --region ${REGION} --capabilities CAPABILITY_NAMED_IAM)
    status=$?
    set -e

    echo "$update"

    if [ $status -ne 0 ] ; then

        # Don't fail for no-op update
        if [[ $update == *"ValidationError"* && $update == *"No updates"* ]] ; then
            echo -e "\nFinished create/update - no updates to be performed"
            exit 0
        else
            exit $status
        fi

    fi

    echo "Waiting on ${STACK} to update..."
    aws cloudformation wait stack-update-complete --stack-name ${STACK} --region ${REGION}
fi

echo "Finished create/update successfully!"