Steps to reproduce

• Install ActiveStorage
• Create a Post model with rails g model Post title:string & migrate
• Add has_one_attached :image to the Post model
• Add this code to db/seeds.rb:

post = Post.create(title: 'Test post')
post.image.attach(io: File.open("#{Rails.root}/test.png"), filename: "test.png")

• Add a sample image with the file name test.png at the Rails root directory
• Run rails db:drop db:create db:migrate db:seed

Expected behavior

rails db:seed should run & exit successfully.

Actual behavior

rails db:seed will successfully seed the database but it will not exit the process.

System configuration

Rails version: 5.2.0

Ruby version: ruby 2.5.1p57

Attempts to fix

I tried referencing the file by a variable image = File.open("#{Rails.root}/test.png") & then attaching it to the post like this post.image.attach(io: image, filename: "test.png") & finally closing the file with image.close. It still caused the process to hang.

Workaround

Adding config.active_job.queue_adapter = :inline to config/environments/development.rb will fix the issue for some reason, I'm not quite sure why. That's why I'm guessing this issue has something to do with the inner workings of ActiveJob.