fluke/devops-service/db/mongo/models/stack_template/stack_template_base.rb

require 'tempfile'
require 'securerandom'

module Devops
  module Model
    class StackTemplateBase < MongoModel

      attr_accessor :id, :template_url, :template_json, :provider

      # Few words about template_url:
      # In Amazon Cloudformation the template file must be stored on an Amazon S3 bucket,
      # but for Openstack stacks it isn't neccessary (your may use local file).
      # I decided to enforce template_url strategy using in openstack to reach more common
      # interface between different providers' stack templates.

      types id: {type: String, empty: false},
        provider: {type: String, empty: false},
        template_json: {type: String, empty: false},
        template_url: {type: String, empty: false}

      def initialize(attrs)
        self.id = attrs['id']
        self.template_json = attrs['template_json'].to_s
        self.template_url = attrs['template_url']
        self.provider = attrs['provider']
        self
      end

      def to_hash_without_id
        {
          provider: provider,
          template_json: template_json,
          template_url: template_url
        }
      end

      # do not forget to destroy template files on template destroying
      def delete_template_file_from_storage
        raise 'Override me'
      end

      # attrs should include:
      # - id (String)
      # - provider (String)
      # - template_json (String)
      def self.create(attrs)
        json = attrs['template_json']
        attrs['template_url'] = generate_template_file_and_upload_to_storage(attrs['id'], json)
        new(attrs)
      end

      def self.build_from_bson(attrs)
        attrs['id'] = attrs["_id"]
        self.new(attrs)
      end

      class << self
        private

        def generate_template_file_and_upload_to_storage(id, json)
          tempfile = Tempfile.new('foo')
          tempfile.write(json)
          secure_filename = "#{id}-#{SecureRandom.hex}.template"
          upload_file_to_storage(secure_filename, tempfile.path)
        ensure
          tempfile.close
          tempfile.unlink
        end

        def upload_file_to_storage(filename, file_path)
          raise 'Override me'
        end

      end
    end
  end
end