Use Yarn for Elastic Beanstalk

This article describes how to use yarn (or any other package manager than npm) instead of npm when deploying an Elastic Beanstalk Node.js app.

One problem is that EB will automatically run npm install if it finds a package.json file. An easy way to prevent EB from running npm install is to create an empty node_modules folder in a prebuild hook:

Inside your project root directory (where EB is configured), run:

mkdir -p .platform/hooks/{prebuild,predeploy}

Then create .platform/hooks/prebuild/prevent-npm.sh:

#!/bin/bash
# EB build scripts will not install using npm if node_modules folder exists
mkdir node_modules

This way, EB will still install Node.js, so you don't have to install that yourself. But it will skip npm install when node_modules exists.

Then, inside the predeploy hook, you can run yarn or whatever you like. If you are running Node.js 16 or newer, you can use corepack yarn, and it will just work (you don't have to install yarn from yum, npm or anything else.)

Create .platform/hooks/predeploy/yarn.sh:

#!/bin/bash
corepack yarn

Update: As of Amazon Linux 2023, corepack is no longer included, and needs to be explicitly installed:

Edit your_project/.platform/hooks/prebuild/corepack.sh:

#!/bin/bash
npm i -g corepack

⚠️ Be sure to also create symlinks under confighooks in your project, or else it will fail to build when changing config (e.g. updating environment values):

mkdir -p .platform/confighooks/{prebuild,predeploy}
ln -s ../../hooks/predeploy/yarn.sh .platform/confighooks/predeploy/yarn.sh
ln -s ../../hooks/prebuild/prevent-npm.sh .platform/confighooks/prebuild/prevent-npm.sh
ln -s ../../hooks/prebuild/corepack.sh .platform/confighooks/prebuild/corepack.sh

References:​

References: