Yarn cache for ephemeral VMs using GCS + fuse (gcsfuse)

cache

#!/bin/bash

GREEN='\033[0;32m'
YELLOW='\033[1;33m'
ORANGE='\033[0;33m'
RED='\033[0;31m'
DEFAULT='\033[0m'

BUCKET=challenge-correction-cache
HOME_DIR=/home/deploy
MOUNT_DIR=cache-bucket
TAR_FILE=cache.tar.gz

show_help=false
help_command=rehydrate
help_info="  Rehydrate the GCS bucket cache with the local yarn cache."

help() {
  echo
  echo -e "  Usage: ${GREEN}cache ${YELLOW}[command]"
  echo
  echo "  Displays help information."
  echo
  echo "  Commands:"
  echo "    - rehydrate"
  echo "    - restore"
  echo
  echo -e "  Run ${GREEN}cache ${ORANGE}help ${YELLOW}[command] ${DEFAULT}for more information on specific commands."
  echo
}

show_command_help() {
  echo
  echo -e "  Usage: ${GREEN}cache ${YELLOW}$help_command"
  echo
  echo $help_info
  echo
}

rehydrate() {
  if [[ "x$show_help" == "xtrue" ]] ; then
    help_command=rehydrate
    help_info="  Rehydrate the GCS bucket cache with the local yarn cache."
    show_command_help
    return
  fi

  (cd $HOME_DIR && \
   tar -zcg cache.snap -f $TAR_FILE .cache && \
   cp $TAR_FILE "$MOUNT_DIR"/"$TAR_FILE")
}

restore() {
  if [[ "x$show_help" == "xtrue" ]] ; then
    help_command=restore
    help_info="  Restore yarn cache from GCS bucket."
    show_command_help
    return
  fi

  (cd $HOME_DIR && \
   cp "$MOUNT_DIR"/"$TAR_FILE" $TAR_FILE && \
   tar -xzf $TAR_FILE)
}

check_fs() {
  if ! mount -l | grep fuse &>/dev/null; then
    echo
    echo -e "  ${ORANGE}[WARN] ${DEFAULT}Remote file system not mounted."
    echo
    echo "  Creating user-space file system for interacting with GCS bucket..."
    (cd $HOME_DIR && fusermount -u cache-bucket/ 2>&1)
    if ! result=$(cd $HOME_DIR && gcsfuse $BUCKET $MOUNT_DIR 2>&1) ; then
      gcs_fail=true
    fi
    [[ "x$gcs_fail" == "xtrue" ]] && echo -e "\n  ${RED}[ERROR] ${DEFAULT}Failed to create user-space file system:" >&2
    fmt_result="$(echo $result | sed 's/^/  /g')"
    echo -e "\n${fmt_result}"
    [[ "x$gcs_fail" == "xtrue" ]] && exit 1
  fi
}

check_fs

case "$1" in
  -h | --help)
    help
    exit 0
    ;;
  help)
    case "$2" in
      rehydrate)
        show_help=true
        rehydrate
        exit 0
        ;;
      restore)
        show_help=true
        restore
        exit 0
        ;;
      "")
        help
        exit 0
        ;;
      *)
        echo
        echo -e "  ${RED}[ERROR] ${DEFAULT}Unknown command: ${YELLOW}$2" >&2
        help
        exit 1
        ;;
    esac
    ;;
  rehydrate)
    rehydrate
    exit 0
    ;;
  restore)
    restore
    exit 0
    ;;
  -* | --*)
    echo
    echo -e "  ${RED}[ERROR] ${DEFAULT}Unknown option: ${YELLOW}$1" >&2
    help
    exit 1
    ;;
  *)
    help
    exit 1
    ;;
esac