node_modules folder caching on build servers

yarncache.sh

#!/bin/bash

# set ACCESS_TOKEN with gcloud auth print-access-token
UPLOAD_URL="https://storage.googleapis.com/<project>-npmcache"

SCRIPT_PATH=$(cd `dirname ${0}`; pwd)
YARN_LOCK_HASH=`cat yarn.lock package.json|sha1sum|cut -d' ' -f1`

if [ ! -d "node_modules" ]; then
  echo "Trying to extract cached yarn dump"
  curl -L -v "$UPLOAD_URL/$YARN_LOCK_HASH.tar.gz" | tar -xz
fi

if [ -f "node_modules/$YARN_LOCK_HASH.yarncache" ]; then
  echo "Skipping yarn because we already got a node_modules folder"
else
  yarn
  if [[ -n "$ACCESS_TOKEN" ]]; then
    echo "Creating $YARN_LOCK_HASH.tar.gz of node_modules"
    touch "node_modules/$YARN_LOCK_HASH.yarncache"
    tar -czf $YARN_LOCK_HASH.tar.gz node_modules
    curl -L -v -H "Authorization: Bearer $ACCESS_TOKEN" --upload-file $YARN_LOCK_HASH.tar.gz "$UPLOAD_URL/"
  else
    echo "No ACCESS_TOKEN set, so not uploading $YARN_LOCK_HASH.tar.gz";
  fi
fi