Elastic Beanstalk Rails+Webpacker extension

yarm.config

# Copyright 2018 SwiftComply.com
commands:
  01_node_install:
    test: "[ `node --version` != 'v8.10.0' ]"
    command: "curl --silent --location https://rpm.nodesource.com/setup_8.x | sudo bash -"
  02_yarn_repo:
    test: "[ ! -f /etc/yum.repos.d/yarn.repo ]"
    command: "curl --silent --location https://dl.yarnpkg.com/rpm/yarn.repo | sudo tee /etc/yum.repos.d/yarn.repo"
  03_yarn_install:
    test: "[ ! -x /usr/bin/yarn ]"
    command: "yum install -y yarn"
files:
  # If this file is edited, it must be removed from EC2 instance prior to deploy.
  "/opt/elasticbeanstalk/hooks/appdeploy/pre/09_yarn_install.sh" :
    mode: "00555"
    owner: root
    group: root
    content: |
      #!/usr/bin/env bash
      #==============================================================================
      # Copyright 2018 SwiftComply.com
      #
      # This file is distributed on
      # an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or
      # implied.
      #==============================================================================

      . /opt/elasticbeanstalk/hooks/common.sh

      set -xe

      EB_SCRIPT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k script_dir)
      EB_APP_STAGING_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k app_staging_dir)
      EB_APP_USER=$(/opt/elasticbeanstalk/bin/get-config container -k app_user)
      EB_SUPPORT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k support_dir)

      . $EB_SUPPORT_DIR/envvars

      cd $EB_APP_STAGING_DIR

      if [ -f package.json ]; then
          echo "running 'yarn install' with package.json:"
          cat package.json
          ./bin/yarn install
      else
          echo "no package.json found! Skipping yarn install stage!"
      fi

      if [ -f yarn.lock ]; then
          echo "encountered a yarn.lock, setting proper permissions"
          chown $EB_APP_USER:$EB_APP_USER yarn.lock
      else
          echo "no yarn.lock file found, so no permissions to set on it"
      fi