Heroku delete my uploaded files, why? - ruby-on-rails

Question

if I load the file in my app on Heroku, everything works, but when I tried again to reload the application, it gives me the following error:
2013-01-25T08:48:31+00:00 app[web.1]: app/controllers/main_controller.rb:20:in `index'
2013-01-25T08:48:31+00:00 app[web.1]:
2013-01-25T08:48:31+00:00 app[web.1]:
2013-01-25T08:48:31+00:00 app[web.1]: Errno::ENOENT (No such file or directory - /app/config/cases/casesID6.yml):
2013-01-25T08:48:31+00:00 app[web.1]: app/controllers/main_controller.rb:20:in `read'
LOCALLY IT WORK FINE !
main controller:
# importo yaml di configurazione
require 'yaml'
if Survey.exists?(1)
#idOfSurvey = Survey.find {|s| s['active_state'] == true}['id']
nameOfSurvey = "casesID"+String(#idOfSurvey)+".yml"
#survey = YAML::load(ERB.new(IO.read(File.join(Rails.root, 'config/cases', nameOfSurvey))).result)
else
render :action => 'noYaml' and return
end
upload controller :
#inserisco il nuovo questionario
survey = Survey.new
if Survey.exists?(1)
n = String(Integer(Survey.maximum("Id"))+1)
survey.name = "casesID#{n}"
else
survey.name = "casesID1"
end
File.open(Rails.root.join('config/cases', survey.name+".yml"), 'wb+') do |file|
file.write(uploaded_io.read)
end
survey.save()
I believe that my file uploaded to Heroku, may be cleared by the platform for issues of memory, for example, or because it saves them as temporary, is this possible? solutions!
I repeat, everything works fine locally :(

Answer 1

Whilst you can write to the Heroku filesystem once you scale, restart or push a new version of your code then the file will be gone.
You need to use a persistant file store such as Amazon S3, Rackspace or such like - read more at https://devcenter.heroku.com/articles/dynos#ephemeral-filesystem and use a gem like CarrierWave or Paperclip which make connecting to S3 super simple.