mongo-on-ramdisk

#!/usr/bin/env bash -x

# Creates RAM disk.
#
# SYNOPSIS
#   create_ramdisk [size [label]]
#
# OPTIONS
#   size:  RAM disk size in megabytes. Default: 1024
#   label: RAM disk volume label. Default: UUID
#
# RETURN VALUE
#   Created RAM disk device path.
create_ramdisk() {
  # Digits after `ram://` denote amount of 512B sectors.
  local sectors=$((${1:-1024} * 1024 * 1024 / 512))
  local ramdisk=$(hdiutil attach -nomount ram://$sectors)

  diskutil eraseVolume "HFS+" "${2:-$(uuidgen)}" "$ramdisk"

  echo "$ramdisk"
}

mount_ramdisk() {
  local ramdisk="$1"
  local mount_point="$2"

  diskutil unmount "$ramdisk"

  mkdir -p "$mount_point"
  mount -t hfs -o noatime "$ramdisk" "$mount_point"

  chflags hidden "$mount_point"
}

start_mongo() {
  sudo ifconfig lo0 alias 127.0.0.2 up
  sudo mongod --bind_ip "127.0.0.2" --dbpath "$1"
}

main() {
  local mount_point="/Users/${USER}/mongodb-ramdisk"
  local ramdisk=$(create_ramdisk 256)

  mount_ramdisk "$ramdisk" "$mount_point"
  start_mongo "$mount_point"
}

main