#!/bin/bash

# This script will retrieve the latest Amazon Linux AMIs.
# Each AMI will be displayed one per line, and for each line,
# you'll get tab separated output:
#
# region  image_id  name  description
#
#
# If you run this script with no arguments you'll get the
# AMIs in every region.  Otherwise you can provide
# a "-r | --region" option that will only display
# images for the specified region.

list_amis() {
  # Tab separated output
  # region	image_id	name	description
  local region_name="$1"
  aws ec2 describe-images \
    --filters \
      Name=owner-alias,Values=amazon \
      Name=name,Values="amzn-ami-hvm-*" \
      Name=architecture,Values=x86_64 \
      Name=virtualization-type,Values=hvm \
      Name=root-device-type,Values=ebs \
      Name=block-device-mapping.volume-type,Values=gp2 \
  --region "$region_name" \
  --query "reverse(sort_by(Images[? !contains(Name, 'rc')], &CreationDate))[*].['$region_name',ImageId,Name,Description]" \
  --output text
}


if [ -z "$1" ]; then
  for region_name in $(aws ec2 describe-regions --query "sort(Regions[].RegionName)" --output text); do
    list_amis "$region_name"
  done
else
  case "$1" in
    -r|--region)
      shift
      region_name="$1"
      ;;
    *)
      echo "usage: latest-amis [-r | --region]" 1>&2
      exit 1
  esac
  list_amis "$region_name"
fi