Broken images when seeding database on heroku - ruby-on-rails

Question

I have a Rails 4 application that uses paperclip to attach photos. My db/seeds.rb file adds some photos for my Person model with lines like this:
Person.create(:first_name => 'Jon', :last_name => 'Snow',
:photo => File.open("#{Rails.root}/app/assets/images/jon-snow.png))
In my app/models/person.rb file I have the :photo as a paperclip attachment where it is cropped and resized:
class Person < ActiveRecord::Base
has_attached_file :photo,
:styles => { :medium => "256x256#", :small => "64x64#", :tiny => "24x24#" },
:default_url => :set_default_avatar,
:url => "/assets/photos/:id/:style/:basename.:extension",
:path => ":rails_root/public/assets/photos/:id/:style/:basename.:extension"
validates_attachment_size :photo, :less_than => 5.megabytes
validates_attachment_content_type :photo, :content_type => ['image/jpeg', 'image/png']
My problem is that when I try to deploy this to heroku (with the Cedar stack) and then seed the database, the images all come up as broken. However, on my local computer everything comes up completely fine.
The broken image tag that is generated on heroku might look something like:
<img alt="Jon Snow" src="/assets/photos/21/small/jon-snow.png?1386825683">
Does anyone know why this link would break on heroku but not on my computer? I know that heroku is generating the resized photos because the heroku console outputs things similar to what is in this post: Seed images in heroku with paperclip.
However, it is putting them into public/assets instead of in public/assets/photos/:id/:style/:basename.:extension as the controller specifies.
I've tried doing what that linked post mentions, as well as running:
heroku run rake assets:precompile
and a number of other things, but nothing works. Any help would be greatly appreciated.

Answer 1

The issue is the same I described in this answer How to use paperclip with rails and how does it work in deployment?
The legacy Bamboo stack had a read-only file system so you were unable to write on the file-system.
In the new Cedar stack, the file system is no longer read-only, so the upload will not fail. However, you should keep using AWS or any other external storage because Heroku distributes your compiled application across several machines, and it's not guaranteed that the image will be visible from another request. They call it ephemeral filesystem.
In other words, you should keep using AWS or any other storage outside Heroku file-system.

Answer 2

From heroku-dev
The filesystem for the slug is read-only, which means you cannot
dynamically write to the filesystem for semi-permanent storage. The
following types of behaviors are not supported: Caching pages in the
public directory Saving uploaded assets to local disk (e.g. with
attachment_fu or paperclip)
Use AWS S3