Speedup node modules installation if cache exists on s3

npm-install.sh

#!/usr/bin/env bash

NPM_TARBALL=node_modules.tgz
NPM_MD5SUM_FILE=package-lock.md5sum
NPM_CACHE_DIR=${HOME}/.cache/YOUR_PROJECT/npmtarball
S3_DIR=s3://YOUR_BUCKET/YOUR_PROJECT

function shouldInstallFromCache() {
	printf "\nChecking the cache\n"
	[[ ! -e $NPM_CACHE_DIR ]] && mkdir -p $NPM_CACHE_DIR
	cd $NPM_CACHE_DIR
	if aws s3 cp ${S3_DIR}/${NPM_MD5SUM_FILE} ./${NPM_MD5SUM_FILE}; then
		printf "Downloaded cached package-lock.json\n"
	else
		touch ${NPM_MD5SUM_FILE}
		printf "No package-lock.json cached yet\n"
	fi
	cd -
	md5 package-lock.json >${NPM_MD5SUM_FILE}

	if diff ${NPM_CACHE_DIR}/${NPM_MD5SUM_FILE} ${NPM_MD5SUM_FILE}; then
		return 0
	else
		return 1
	fi
}

function installFromCache() {
	aws s3 cp ${S3_DIR}/${NPM_TARBALL} ${NPM_CACHE_DIR}/${NPM_TARBALL}
	tar xzf ${NPM_CACHE_DIR}/${NPM_TARBALL}
}

function updateCache() {
	tar -zcf ${NPM_TARBALL} node_modules
	mv ${NPM_TARBALL} ${NPM_CACHE_DIR}
	mv ${NPM_MD5SUM_FILE} ${NPM_CACHE_DIR}
	cd $NPM_CACHE_DIR
	aws s3 cp ./$NPM_TARBALL $S3_DIR/$NPM_TARBALL
	aws s3 cp ./$NPM_MD5SUM_FILE $S3_DIR/$NPM_MD5SUM_FILE
	cd -
}

function md5() {
	md5sum $1 | cut -d\  -f 1
}

function installModules() {
	if shouldInstallFromCache; then
		printf "\nInstalling from cache\n"
		installFromCache
	else
		printf "\nInstalling from scratch\n"
		npm install

		printf "\nUpdating the cache\n"
		updateCache
	fi
}

installModules