do-volume

#!/bin/bash
set -euo pipefail
exec 3>&1 # Preserve stdout
exec > "/tmp/do-volume.$(id -gn).log" 2>&1

DEV_PREFIX="/dev/disk/by-id/scsi-0DO_Volume_"
DO_API="https://api.digitalocean.com"
DO_TOKEN=

CURL="curl -LSsf"
DROPLET_ID=$($CURL "http://169.254.169.254/metadata/v1/id")
REGION=$($CURL "http://169.254.169.254/metadata/v1/region")
ACTION=

ocean() {
  local action=$1
  local path=$2
  shift 2
  args=$(echo "$@" | sed 's/\([^ ][^=]*\)=\([^ ]*\)/"\1": "\2",/g;s/,$//')
  $CURL -X "$action" "$DO_API/$path" \
    -H 'Content-Type: application/json' \
    -H "Authorization: Bearer $DO_TOKEN" \
    -d "{ $args }" 2>&1 # If curl suceeds, output is only stdout. If fails, only stderr
}

fatal() {
  local msg="$1"
  local device="${2:-}"
  [ -t 2 ] && echo "Fatal: $msg" >&2
  echo '{ "status": "Failure", "message": "'$msg'", "device": "'$device'" }' >&3
  exit 1
}

success() {
  local device="$1"
  local msg="${2:-}"
  [ -t 2 ] && echo "Success: $msg" >&2
  echo '{ "status": "Success", "message": "'$msg'", "device": "'$device'" }' >&3
  exit 0
}

init_vol() {
  if ! which jq > /dev/null; then
    fatal "jq required but not found in path" >&2
  fi
  success ""
}

attach_vol() {
  local name=$(echo "$1" | jq -r .volume)

  attached_id=$(ocean GET "v2/volumes?name=$name&region=$REGION" \
    | jq -r '.volumes[0].droplet_ids[0]') \
      || fatal "Couldn't retrieve volume"

  if [[ "$attached_id" != "null" ]]; then
    if [[ "$attached_id" -eq "$DROPLET_ID" ]]; then
      success "${DEV_PREFIX}$name" "already attached"
    fi
    fatal "Volume already attached to $attached_id"
  fi

  response=$(ocean POST "v2/volumes/actions" \
    "type=attach" \
    "droplet_id=$DROPLET_ID" \
    "volume_name=$name" \
    "region=$REGION" \
  ) || fatal "Couldn't attach volume: $response"
  success "${DEV_PREFIX}$name"
}

device_to_name() {
  local device="$1"
  if [[ $device != ${DEV_PREFIX}* ]]; then
    for f in ${DEV_PREFIX}*; do
      t=$(readlink -f "$f")
      if [[ "$t" == "$device" ]]; then
	device="$f"
	break
      fi
    done
  fi
  echo "${device#${DEV_PREFIX}}"
}

detach_vol() {
  local device="$1"
  local name=$(device_to_name "$device")
  response=$(ocean POST "v2/volumes/actions" \
    "type=detach" \
    "droplet_id=$DROPLET_ID" \
    "volume_name=$name" \
    "region=$REGION"
  ) || fatal "Couldn't detach volume: $response"
  success "$device"
}

mount_vol() {
  local mnt="$1"
  local device="$2"
  mkdir -p "$mnt"
  mount "$device" "$mnt" || fatal "Couldn't mount $device on $mnt"
  success "$device"
}

unmount_vol() {
  local mnt="$1"
  local device=$(grep "$mnt" /etc/mtab|cut -d' ' -f1)
  if [[ -z "$device" ]]; then
    success "$device" "Volume not mounted"
  fi
  umount "$mnt" || fatal "Couldn't unmount $mnt"
  success "$device"
}

create_vol() {
  local name="$1"
  local size="$2"
  shift 2
  local comment="$@"
  ocean POST "v2/volumes" \
    "name=$name" \
    "size_gigabytes=$size" \
    "comment=$comment" \
    "region=$REGION" \
    || fatal "Couldn't create volume"
}

main() {
  if [ "$#" -lt 1 ]; then
    fatal "Missing argument. Syntax: $0 create|init|attach|detach|mount|unmount"
  fi
  ACTION=$1
  shift

  DO_TOKEN=$(cat /etc/do.token 2>/dev/null) \
    || fatal "/etc/do.token missing or unreadable"

  if [ -n "${DEBUG:-}" ]; then
    CURL="curl -Lf"
    set -x
  fi

  case "$ACTION" in
    init)
      init_vol "$@"
      ;;
    attach)
      [ "$#" -lt 1 ] && fatal "Missing argument. Syntax $0 attach <json-options>"
      attach_vol "$@"
      ;;
    detach)
      [ "$#" -lt 1 ] && fatal "Missing argument. Syntax $0 detach <mount-device>"
      detach_vol "$@"
      ;;
    mount)
      [ "$#" -lt 2 ] && fatal "Missing argument. Syntax $0 mount <target mount dir> <mount-device> <json options>"
      mount_vol "$@"
      ;;
    unmount)
      [ "$#" -lt 1 ] && fatal "Missing argument. Syntax $0 unmount <mount dir>"
      unmount_vol "$@"
      ;;
    create)
      [ "$#" -lt 2 ] && fatal "Missing argument. Syntax $0 create <name> <size-in-gb> [description...]"
      create_vol "$@"
      ;;
    *)
      fatal "Invalid action $ACTION"
      ;;
  esac
}

main "$@"