Here's a Ruby script that deletes unused images (snapshots) on Hetzner

HETZNER-IMAGE-CLEANUP.md

Delete unused Hetzner images

I write images on Hetzner using Packer, but it becomes quite a pain to clean them up manually, luckily there's an API, so I built a quick script that does two things:

• Fetch all images in use by servers.
• Fetch all available images on Hetzner.

It then compares the 2, and offers you to delete the unused images.

Usage:

ruby unused_hetzner_image_deletion.rb

Examples

When images to delete:

3 image(s) in use:
- 192188323: shared-server-2.0.3
- 192188339: nomad-client-0.1.10
- 192732826: buildkite-0.0.6

8 image(s) to delete:
- 180526387: nomad-client-0.1.1
- 180558880: nomad-client-0.1.3
- 180928223: nomad-client-0.1.5
- 182489275: shared-server-2.0.1
- 182491740: nomad-client-0.1.6
- 182508392: nomad-client-0.1.7
- 182630086: nomad-client-0.1.8
- 185031268: nomad-client-0.1.9

.. delete 8 images? (Y/n)Y
Deleting nomad-client-0.1.1..!
Deleting nomad-client-0.1.3..!
Deleting nomad-client-0.1.5..!
Deleting shared-server-2.0.1..!
Deleting nomad-client-0.1.6..!
Deleting nomad-client-0.1.7..!
Deleting nomad-client-0.1.8..!
Deleting nomad-client-0.1.9..!

When no images to delete:

3 image(s) in use:
- 192188323: shared-server-2.0.3
- 192188339: nomad-client-0.1.10
- 192732826: buildkite-0.0.6

No unused images
.. bye!

unused_hetzner_image_deletion.rb

# A quick and dirty image deletion 
API_KEY = ''

require 'uri'
require 'net/http'
require 'openssl'
require 'json'

def json_get(url)
  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_PEER

  request = Net::HTTP::Get.new(url)
  request['Authorization'] = "Bearer #{API_KEY}"

  response = http.request(request)
  JSON.parse(response.read_body)
end

def delete(url)
  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_PEER

  request = Net::HTTP::Delete.new(url)
  request['Authorization'] = "Bearer #{API_KEY}"

  response = http.request(request)
  raise "Error deleting #{url}" if response.code != '204'

  response
end

Pagination = Struct.new(:page, :next_page) do
  def more?
    next_page != nil
  end
end

def parse_pagination(request_json)
  pagination = request_json['meta']['pagination']

  Pagination.new.tap do |pagy|
    pagy.page = pagination['page']
    pagy.next_page = pagination['next_page']
  end
end

Image = Struct.new(:id, :name, :description, :deleted, :type) do
  def snapshot?
    type == 'snapshot'
  end
end

def parse_server_images(request_json)
  [].tap do |images|
    request_json['servers'].each do |server|
      images << Image.new.tap do |image|
        image.id = server['image']['id']
        image.name = server['image']['labels']['imagename']
        image.description = server['image']['description']
        image.deleted = server['image']['deleted']
        image.type = server['image']['type']
      end
    end
  end
end

def parse_images(request_json)
  [].tap do |images|
    request_json['images'].each do |image_json|
      images << Image.new.tap do |image|
        image.id = image_json['id']
        image.name = image_json['labels']['imagename']
        image.description = image_json['description']
        image.deleted = image_json['deleted']
        image.type = image_json['type']
      end
    end
  end
end

images_in_use = [].tap do |images|
  page_id = 1
  loop do
    json = json_get(URI("https://api.hetzner.cloud/v1/servers?per_page=3&page=#{page_id}&status=running"))

    images.concat(parse_server_images(json))

    pagy = parse_pagination(json)
    break unless pagy.more?

    page_id += 1
  end
end.uniq(&:id).select(&:snapshot?)

images_available = [].tap do |images|
  page_id = 1
  loop do
    json = json_get(URI("https://api.hetzner.cloud/v1/images?per_page=3&page=#{page_id}&type=snapshot"))

    images.concat(parse_images(json))

    pagy = parse_pagination(json)
    break unless pagy.more?

    page_id += 1
  end
end.select(&:snapshot?)

images_to_delete = [].tap do |images|
  images_available.each do |available_image|
    next if images_in_use.any? { |i| i.id == available_image.id }

    images << available_image
  end
end

puts "#{images_in_use.size} image(s) in use:"
images_in_use.each do |image|
  puts "- #{image.id}: #{image.name}"
end
puts ''

if images_to_delete.any?
  puts "#{images_to_delete.size} image(s) to delete:"
  images_to_delete.each do |image|
    puts "- #{image.id}: #{image.name}"
  end
  puts ''
  print ".. delete #{images_to_delete.size} images? (Y/n)"

  answer = gets.chomp
  if answer == 'Y'
    images_to_delete.each do |image|
      print "Deleting #{image.name}.."
      delete(URI("https://api.hetzner.cloud/v1/images/#{image.id}"))
      print "!\n"
    end
  else
    puts 'Bye!'
  end
else
  puts 'No unused images'
  puts '.. bye!'
end