Marat's Notes

As a part of my idea of Yandex Disk as ActiveStorage service implementation, I decided to implement PROPPATCH method into yandex disk gem.

As described in webdav documentation - all what we need - make a special PROPPATCH request with PATH of our folder or file.

We need to set proper option in development.rb:

 config.active_storage.service = :yandex_disk

When we need to add special section ino storage.yml file:

yandex_disk:
  service: YandexDisk
  access_token: "XXXXXXXXXXXXXXXXXXXXXXXX"

Let’s create /lib/active_storage/service/yandex_disk_service.rb. We need to inherit our new service from Service

require "yandex/disk"

module ActiveStorage
  # Wraps the Yandex Disk Service as an Active Storage service.
  # See ActiveStorage::Service for the generic API documentation that applies to all services.
  class Service::YandexDiskService < Service
    attr_reader :client

    def initialize(access_token:)
      @client = Yandex::Disk::Client.new(access_token: access_token)
    end

    def upload(key, io, checksum: nil)
      instrument :upload, key: key, checksum: checksum do
        begin
          # pseudocode - we can specify here local path to file, or read IO object
          @client.put(LOCAL_FILE_PATH, DESTINATION_FILE_PATH)
        rescue
          raise ActiveStorage::IntegrityError
        end
      end
    end
  end 
end

Of course, it’s not a final implementation, we should implement another methods, as described here: current active_storage services.

For example azure_storage_service.rb:

# frozen_string_literal: true

require "active_support/core_ext/numeric/bytes"
require "azure/storage"
require "azure/storage/core/auth/shared_access_signature"

module ActiveStorage
  # Wraps the Microsoft Azure Storage Blob Service as an Active Storage service.
  # See ActiveStorage::Service for the generic API documentation that applies to all services.
  class Service::AzureStorageService < Service
    attr_reader :client, :path, :blobs, :container, :signer

    def initialize(path:, storage_account_name:, storage_access_key:, container:)
      @client = Azure::Storage::Client.create(storage_account_name: storage_account_name, storage_access_key: storage_access_key)
      @signer = Azure::Storage::Core::Auth::SharedAccessSignature.new(storage_account_name, storage_access_key)
      @blobs = client.blob_client
      @container = container
      @path = path
    end

    def upload(key, io, checksum: nil)
      instrument :upload, key: key, checksum: checksum do
        begin
          blobs.create_block_blob(container, key, io, content_md5: checksum)
        rescue Azure::Core::Http::HTTPError
          raise ActiveStorage::IntegrityError
        end
      end
    end

    def download(key, &block)
      if block_given?
        instrument :streaming_download, key: key do
          stream(key, &block)
        end
      else
        instrument :download, key: key do
          _, io = blobs.get_blob(container, key)
          io.force_encoding(Encoding::BINARY)
        end
      end
    end

    def delete(key)
      instrument :delete, key: key do
        begin
          blobs.delete_blob(container, key)
        rescue Azure::Core::Http::HTTPError
          # Ignore files already deleted
        end
      end
    end

    def delete_prefixed(prefix)
      instrument :delete_prefixed, prefix: prefix do
        marker = nil

        loop do
          results = blobs.list_blobs(container, prefix: prefix, marker: marker)

          results.each do |blob|
            blobs.delete_blob(container, blob.name)
          end

          break unless marker = results.continuation_token.presence
        end
      end
    end

    def exist?(key)
      instrument :exist, key: key do |payload|
        answer = blob_for(key).present?
        payload[:exist] = answer
        answer
      end
    end

    def url(key, expires_in:, filename:, disposition:, content_type:)
      instrument :url, key: key do |payload|
        base_url = url_for(key)
        generated_url = signer.signed_uri(
          URI(base_url), false,
          permissions: "r",
          expiry: format_expiry(expires_in),
          content_disposition: content_disposition_with(type: disposition, filename: filename),
          content_type: content_type
        ).to_s

        payload[:url] = generated_url

        generated_url
      end
    end

    def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
      instrument :url, key: key do |payload|
        base_url = url_for(key)
        generated_url = signer.signed_uri(URI(base_url), false, permissions: "rw",
          expiry: format_expiry(expires_in)).to_s

        payload[:url] = generated_url

        generated_url
      end
    end

    def headers_for_direct_upload(key, content_type:, checksum:, **)
      { "Content-Type" => content_type, "Content-MD5" => checksum, "x-ms-blob-type" => "BlockBlob" }
    end

    private
      def url_for(key)
        "#{path}/#{container}/#{key}"
      end

      def blob_for(key)
        blobs.get_blob_properties(container, key)
      rescue Azure::Core::Http::HTTPError
        false
      end

      def format_expiry(expires_in)
        expires_in ? Time.now.utc.advance(seconds: expires_in).iso8601 : nil
      end

      # Reads the object for the given key in chunks, yielding each to the block.
      def stream(key)
        blob = blob_for(key)

        chunk_size = 5.megabytes
        offset = 0

        while offset < blob.properties[:content_length]
          _, chunk = blobs.get_blob(container, key, start_range: offset, end_range: offset + chunk_size - 1)
          yield chunk.force_encoding(Encoding::BINARY)
          offset += chunk_size
        end
      end
  end
end

Let’s take a look, how is our draft implementation working with our Job model with company_logo attachment:

require 'yandex/disk'
yandex_service = ActiveStorage::Service::YandexDiskService.new(access_token: 'XXXXXXXXXXX')
job = Job.new
job.company_logo.attach(io: File.open(Rails.root.join("public", "google.png")), filename: 'google.png' , content_type: "image/png")

And the output:

irb(main):009:0> job = Job.first
=> #<Job id: 1, title: "Rails developer", description: "New Jobs", email: "test@google.com", company: "Google", website: "http://google.com", salary_min: 100, salary_max: 1000, currency: "", status: nil, approved: nil, expire_at: nil, approved_at: nil, created_at: "2018-02-03 17:55:21", updated_at: "2018-02-03 22:51:40">
irb(main):010:0> job.company_logo.attach(io: File.open(Rails.root.join("public", "google.png")), filename: 'google.png' , content_type: "image/png")
  YandexDisk Storage (1099.5ms) Uploaded file to key: SSkvsod6Vme8Q4g3qPu7sicm (checksum: Es4hFkEdVEWDUDrSm6qrhw==)
   (0.3ms)  BEGIN
  ActiveStorage::Blob Create (18.6ms)  INSERT INTO "active_storage_blobs" ("key", "filename", "content_type", "metadata", "byte_size", "checksum", "created_at") VALUES ($1, $2, $3, $4, $5, $6, $7) RETURNING "id"  [["key", "SSkvsod6Vme8Q4g3qPu7sicm"], ["filename", "google.png"], ["content_type", "image/png"], ["metadata", "{\"identified\":true}"], ["byte_size", 13774], ["checksum", "Es4hFkEdVEWDUDrSm6qrhw=="], ["created_at", "2018-02-03 22:54:29.809896"]]
   (5.9ms)  COMMIT
   (0.2ms)  BEGIN
  ActiveStorage::Attachment Create (6.2ms)  INSERT INTO "active_storage_attachments" ("name", "record_type", "record_id", "blob_id", "created_at") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["name", "company_logo"], ["record_type", "Job"], ["record_id", 1], ["blob_id", 6], ["created_at", "2018-02-03 22:54:29.850081"]]
  Job Update All (0.4ms)  UPDATE "jobs" SET "updated_at" = '2018-02-03 22:54:29.857617' WHERE "jobs"."id" = $1  [["id", 1]]
   (6.1ms)  COMMIT

If you do a simple select on ActiveStorage tables, you can see our uploaded image information.

Of course, it’s not a final implementation - it’s just a draft, but I’ll continue work when I have more free time, and I hope you understood main idea.

YandexDisk as ActiveStorage service