hosts.rb

#!/usr/bin/env ruby
require 'dotenv/load'
require 'net/http'
require 'uri'
require 'json'
require 'optparse'

class DigitalOcean
  class << self
    def list
      request = Net::HTTP::Get.new('/v2/droplets')
      request.add_field('Content-Type', 'application/json')
      request.add_field('Authorization', authorization)

      response = with_http do |http|
        http.request request
      end

      JSON.parse(response.body)
    end

    private

    def with_http(&block)
      Net::HTTP.start(uri.host, uri.port, use_ssl: use_ssl, &block)
    end

    def use_ssl
      uri.scheme = 'https'
    end

    def uri
      URI('https://api.digitalocean.com')
    end

    def authorization
      "Bearer #{ENV['DIGITALOCEAN_OAUTH_TOKEN']}"
    end
  end
end

OptionParser.new do |opts|
  opts.banner = 'Usage: hosts.rb [options]'

  opts.on('--list') do
    hosts = DigitalOcean.list['droplets'].map { |d| d['name'] }

    puts JSON.dump('digitalocean' => hosts)
  end

  opts.on('--host HOSTNAME') do |hostname|
    droplet = DigitalOcean.list['droplets'].find { |d| d['name'] == hostname }

    puts JSON.dump(
      'digitalocean' => droplet,
      'ansible_host' => droplet['networks']['v4'].first['ip_address']
    )
  end

  opts.on('--ip HOSTNAME') do |hostname|
    droplet = DigitalOcean.list['droplets'].find { |d| d['name'] == hostname }

    puts droplet['networks']['v4'].first['ip_address']
  end
end.parse!