Please excuse me for my poor English.

In our system, we use ActiveStorage in Rails to manage images. This time, we updated Rails from 6.0.3.6 to 6.1.3.2 and encountered the following problem. I would like to know the cause and how to solve the problem.

Problems that occurred

The URL to the images stored in S3 changed before and after the update, and images stored before the update could not be displayed.

Steps to reproduce

• Update Rails from 6.0.3.6 to 6.1.3.2
• Run rails active_storage:update
• Run rails db:migrate
• Open the page with the images that were saved before the Rails update

Source Code

class Image < ApplicationRecord
  include ActiveStorageSupport::SupportForBase64

  after_commit :process_variants

  has_one_base64_attached :file

  def provider_file_url
    key = file.variant(resize_to_limit: [500, 500]).key

    "#{ENV[‘BASE_URL']}/#{key}"
  end

  private

  def process_variants
    return unless file.attachment

    file.variant(resize_to_limit: [500, 500]).processed
  rescue StandardError
    nil
  end
end

# Call URL
image_instance.provider_file_url

Expected behavior

The same URL is generated before and after the Rails update.

Actual behavior

Generated URLs are different before and after Rails update.

Example：

Before update

https://sample.net/variants/zvd2z2dafhrht3yy99l8w9zw54h8/3a8af9a41326f81dcc439e015ab90b5d9d078e2b00dd7d021c4d4ee650e5c6e0

After update

https://sample.net/variants/zvd2z2dafhrht3yy99l8w9zw54h8/ac54d233b136b9f97f4d984f115d2e1c4695c2a0a3994c28d347637301445431

What I investigated

I compared the behavior of ActiveStorage 6.0.3.6 and 6.1.3.2, and found the following differences. However, I have not been able to get to the cause of this.

Added debug code in two places ↓.

① initialize of ActiveStorage::Variant class (source code)

class ActiveStorage::Variant
  # omitted

  def initialize(blob, variation_or_variation_key)
    p '-----------------------------------------------------------------------------------------'
    p 'blob'
    p blob
    p 'variation_or_variation_key'
    p variation_or_variation_key
    p '-----------------------------------------------------------------------------------------'

    @blob, @variation = blob, ActiveStorage::Variation.wrap(variation_or_variation_key)
  end

  # omitted
end

② encode method of ActiveStorage::Variation class (source code)

class ActiveStorage::Variation
  attr_reader :transformations

  class << self
    # omitted

    def encode(transformations)
      p '-----------------------------------------------------------------------------------------'
      p transformations
      p '-----------------------------------------------------------------------------------------'

      ActiveStorage.verifier.generate(transformations, purpose: :variation)
    end
  end

  # omitted
end

Run provider_file_url method

①

ActiveStorage6.0.3.6

"-----------------------------------------------------------------------------------------"
"blob"
#<ActiveStorage::Blob id: ９９９, key: "zvd2z2dafhrht3yy99l8w9zw54h7", filename: "sample.jpg", content_type: "image/jpeg", metadata: {"identified"=>true, "analyzed"=>true}, byte_size: 15789, checksum: "NwtXS6KRF1ty1WxXMicUew==", created_at: "2021-06-02 08:32:15">
"variation_or_variation_key"
{:resize_to_limit=>[500, 500]}
"-----------------------------------------------------------------------------------------"

ActiveStorage6.1.3.2

"-----------------------------------------------------------------------------------------"
"blob"
#<ActiveStorage::Blob id: 999, key: "zvd2z2dafhrht3yy99l8w9zw54h7", filename: "sample.jpg", content_type: "image/jpeg", metadata: {"identified"=>true, "analyzed"=>true}, byte_size: 15789, checksum: "NwtXS6KRF1ty1WxXMicUew==", created_at: "2021-06-02 17:32:15.000000000 +0900", service_name: "amazon">
"variation_or_variation_key"
#<ActiveStorage::Variation:0x00007fa2db230430 @transformations={:format=>"jpg", :resize_to_limit=>[500, 500]}>
"-----------------------------------------------------------------------------------------"

②

ActiveStorage6.0.3.6

"-----------------------------------------------------------------------------------------"
{:resize_to_limit=>[500, 500]}
"-----------------------------------------------------------------------------------------"

ActiveStorage6.1.3.2

"-----------------------------------------------------------------------------------------"
{:format=>"jpg", :resize_to_limit=>[500, 500]}
"-----------------------------------------------------------------------------------------"

As a test, I added a process to remove the :format key in the encode method, and now the URL is generated as before the update.

System configuration

Before update

Rails: 6.0.3.6

Ruby: 2.6.6

Gemfile.lock

    activestorage (6.0.3.6)
      actionpack (= 6.0.3.6)
      activejob (= 6.0.3.6)
      activerecord (= 6.0.3.6)
      marcel (~> 1.0.0)

After update

Rails version: 6.1.3.2

Ruby version: 2.6.6

Gemfile.lock

    activestorage (6.1.3.2)
      actionpack (= 6.1.3.2)
      activejob (= 6.1.3.2)
      activerecord (= 6.1.3.2)
      activesupport (= 6.1.3.2)
      marcel (~> 1.0.0)
      mini_mime (~> 1.0.2)