Check IP addresses against AWS's published ip ranges

aws_ip_ranges.rb

#!/usr/bin/env ruby

require 'ipaddr'
require 'json'
require 'open-uri'

# From https://docs.aws.amazon.com/general/latest/gr/aws-ip-ranges.html#aws-ip-download
source_url = 'https://ip-ranges.amazonaws.com/ip-ranges.json'

file = File.join(__dir__, 'ip-ranges.json')
unless File.exists?(file)
    warn "Downloading from #{source_url} to #{file}..."
    URI.open(source_url) { |data| File.write(file, data.read) }
end

json = File.read('ip-ranges.json')
data = JSON.parse(json)['prefixes']
data_by_prefix = data.map do |d|
    [IPAddr.new(d['ip_prefix']), d]
end.to_h

if ARGV.empty?
    while true
        print "Enter IP address: "
        input = STDIN.gets.strip
        addr = IPAddr.new(input)
        data = data_by_prefix.detect {|prefix, data| prefix.include?(addr) }[1]
        puts data
    end
else
    ARGV.each do |input|
        puts input
        addr = IPAddr.new(input)
        data = data_by_prefix.detect {|prefix, data| prefix.include?(addr) }[1]
        puts data
        puts
    end
end