#!/bin/bash

export TZ="UTC"

usage() {
  echo "$0 - script to mark a specified EC2 AMI as public

Usage:

  $0 --ami <AMI_ID> [<OPTIONS>]

Supported OPTIONS:

  --ami <AMI_ID>            mark AMI_ID as public
  --help                    display this help text
  --region <REGION>         specify region that should be used
                            (if unset defaults to the eu-west-1 zone)
"
}

CMDLINE_OPTS=ami:,help,region:

_opt_temp=$(getopt --name "$0" -o +bch --long ${CMDLINE_OPTS} -- "$@")
if [ $? -ne 0 ]; then
  echo "Try '$0 --help' for more information." >& 2
  exit 1
fi
eval set -- "${_opt_temp}"

while :; do
  case "$1" in
  --ami)
    shift; AMI_ID="$1"
    ;;
  --help)
    usage ; exit 0;
    ;;
  --region)
    shift; AWS_REGION="$1"
    ;;
  --)
    shift; break
    ;;
  *)
    echo "Internal getopt error! $1" >&2
    exit 1
    ;;
  esac
  shift
done

# if unset set sane defaults
[ -n "${AWS_REGION}" ] || AWS_REGION="eu-west-1"

check4progs(){
  local RC=''
  for arg in "$@" ; do
    which "${arg}" >/dev/null 2>&1 || RC="${arg}"
  done
  if [ -n "${RC}" ] ; then
    echo "${RC} not found/executable" >&2
    return 1
  fi
}

if ! check4progs aws ; then
  echo "Required tool aws not found, forgot to install awscli?" >&2
  exit 1
fi

if [ -z "${AMI_ID}" ] ; then
  usage >&2
  exit 1
fi

echo "Marking AMI ${AMI_ID} as public"
aws ec2 modify-image-attribute --region "${AWS_REGION}" --image-id "${AMI_ID}" --launch-permission "Add=[{Group=all}]"
if [ $? -ne 0 ] ; then
  echo "Noticed problem when trying to mark AMI with ID ${AMI_ID} as public." >&2
  exit 1
fi