Execute heroku-cli without local install

install-heroku-cli.sh

#!/bin/bash

set -e
set -u

readonly image='wingrunr21/alpine-heroku-cli'
readonly bashrc="${HOME}/.bashrc"
readonly netrc="${HOME}/.netrc"
readonly heroku_alias="alias heroku='docker run --rm --interactive --tty --volume ${HOME}/.netrc:/root/.netrc --volume '/etc/ssl/certs/ca-certificates.crt:/etc/ssl/certs/ca-certificates.crt:ro' ${image}'"
readonly regexp='^alias heroku.+$'

docker pull ${image}

readonly alias_from_file=$(grep -E "${regexp}" ${bashrc})
if [[ ${alias_from_file} == '' ]]; then
	echo ${heroku_alias} >> ${bashrc}
	source ${bashrc}
else
	if [[ ${alias_from_file} != ${heroku_alias} ]]; then
		readonly replace_slash_pattern="s#/#\\\/#g"
		readonly safe_alias_from_file=$(echo ${alias_from_file} | sed -e ${replace_slash_pattern})
		readonly safe_alias=$(echo ${heroku_alias} | sed -e ${replace_slash_pattern})
		sed -i "s/${safe_alias_from_file}/${safe_alias}/g" ${bashrc}
		source ${bashrc}
	fi
fi

eval ${heroku_alias}
shopt -s expand_aliases
touch ${netrc}
heroku login