custodian

#!/usr/bin/env bash

################################################################################
# Sanity
################################################################################

set -o errexit
set -o nounset
set -o pipefail

################################################################################
# DEBUG
################################################################################

if [[ "${SCRIPT_DBG:-0}" == "1" ]]; then
  set -x
fi

################################################################################
# Globals
################################################################################

# shellcheck disable=SC2155
declare -r SCRIPT_NAME="$(basename "$0")"

declare WATCH_TCP="${WATCH_TCP:-}"
declare WATCH_IDLE="${WATCH_IDLE:-}"
declare DNS_ZONE_ID="${DNS_ZONE_ID:-}"
declare DNS_RECORD="${DNS_RECORD:-}"
declare SNS_TOPIC_ARN="${SNS_TOPIC_ARN:-}"

declare FINISHED=false

################################################################################
# Helpers
################################################################################

function io::print_help() {
  printf '%s\n' "Ben's Terraform AWS Fargate on Demand Custodian"
  printf 'Usage: %s [-h|--help] [options]\n' "$(basename "$0")"
  printf '\t%s\n' "-h, --help: Prints help"
  printf '\t%s\n' ""
  printf '\n%s\n' "Watch Options"
  printf '\t%s\n' "--watch-tcp     (WATCH_TCP)     TCP Port to watch using a iptables rule"
  printf '\t%s\n' "--watch-idle    (WATCH_IDLE)    Number of seconds to remain idle"
  printf '\t%s\n' ""
  printf '\n%s\n' "Required Options"
  printf '\t%s\n' "--dns-zone-id   (DNS_ZONE_ID)   Route 53 Zone ID containing the record to update"
  printf '\t%s\n' "--dns-record    (DNS_RECORD)    Route 53 record to update"
  printf '\t%s\n' ""
  printf '\n%s\n' "Options"
  printf '\t%s\n' "--topic         (SNS_TOPIC_ARN) SNS Topic to send events, if not provided no events will be emitted"
  printf '\t%s\n' ""
}

function io::info() {
  echo "[${SCRIPT_NAME}] INFO $*"
}

function io::die() {
  local msg="${1}"
  local ret="${2:-1}"
  local print_help="${3:-}"

  if [[ ${print_help} == "print help" ]]; then
    io::print_help >&2
  fi

  echo "[${SCRIPT_NAME}] ERROR ${msg}" >&2

  exit "${ret}"
}

function io::die_missing_value() {
  local key="${1}"
  io::die "missing value for argument '${key}'"
}

################################################################################
# Trap
################################################################################

function sigterm() {
  rv=$?

  io::info "Terminating..."

  if [[ "${FINISHED}" = false ]]; then
    io::info "Stopping task..."
    ./task-reaper

    if [[ -n "${SNS_TOPIC_ARN}" ]]; then
      io::info "Emitting stop event..."
      ./event-emitter --type 'stop' --topic "${SNS_TOPIC_ARN}"
    fi
  fi

  io::info "... done"

  exit "${rv}"
}
trap sigterm SIGTERM

################################################################################
# Main
################################################################################

function main() {
  while test $# -gt 0; do
    key="${1}"
    shift

    case "${key}" in
    --help | -h)
      io::print_help
      exit 0
      ;;
    --watch-tcp)
      if [[ $# -lt 1 ]]; then
        io::die_missing_value "${key}"
      fi
      WATCH_TCP="${1}"
      shift
      ;;
    --watch-idle)
      if [[ $# -lt 1 ]]; then
        io::die_missing_value "${key}"
      fi
      WATCH_IDLE="${1}"
      shift
      ;;
    --dns-zone-id)
      if [[ $# -lt 1 ]]; then
        io::die_missing_value "${key}"
      fi
      DNS_ZONE_ID="${1}"
      shift
      ;;
    --dns-record)
      if [[ $# -lt 1 ]]; then
        io::die_missing_value "${key}"
      fi
      DNS_RECORD="${1}"
      shift
      ;;
    --SNS_TOPIC_ARN)
      if [[ $# -lt 1 ]]; then
        io::die_missing_value "${key}"
      fi
      SNS_TOPIC_ARN="${1}"
      shift
      ;;
    *)
      io::info "unsupported option: ${key}"
      ;;
    esac
  done

  io::info "Updating DNS record..."
  ./dns-updater --dns-zone-id "${DNS_ZONE_ID}" --dns-record "${DNS_RECORD}"

  if [[ -n "${SNS_TOPIC_ARN}" ]]; then
    io::info "Emitting start event..."
    ./event-emitter --type 'start' --topic "${SNS_TOPIC_ARN}"
  fi

  if [[ -n "${WATCH_TCP}" ]]; then
    io::info "Starting TCP Port Watcher..."
    ./watcher-tcp \
      --port "${WATCH_TCP}" \
      --events-topic "${SNS_TOPIC_ARN}" \
      --timeout "${WATCH_IDLE}"
  fi

  io::info "Stopping task..."
  ./task-reaper

  if [[ -n "${SNS_TOPIC_ARN}" ]]; then
    io::info "Emitting stop event..."
    ./event-emitter --type 'stop' --topic "${SNS_TOPIC_ARN}"
  fi

  # Prevent double "stop" in trap function
  FINISHED=true

  io::info "... done"
}

################################################################################
# Entry Point
################################################################################

main "$@"