Ruby on Rails + Michael Hartl tutorial + VPS = issues with AWS - ruby-on-rails

Question

I have finished Michael Hartl tutorial and I'm trying to deploy it with https://www.digitalocean.com/community/tutorials/how-to-deploy-a-rails-app-with-puma-and-nginx-on-ubuntu-14-04. Unfortunately I'm stuck with RAILS_ENV=production rake db:migrate because it's generating following error:
ArgumentError: Missing required arguments: aws_access_key_id, aws_secret_access_key
/home/me/simpleapp/config/initializers/carrier_wave.rb:3:in `block in <top (required)>'
/home/me/simpleapp/config/initializers/carrier_wave.rb:2:in `<top (required)>'
/home/me/simpleapp/config/environment.rb:5:in `<top (required)>
'
I have even copied those files 1:1 and still this error persists. Any idea how could I solve it? I really am tired with trying to fix it with different solutions from web.
Thanks
edit: I am adding my carrier_wave file:
if Rails.env.production?
CarrierWave.configure do |config|
config.fog_credentials = {
# Configuration for Amazon S3
:provider => 'AWS',
:aws_access_key_id => ENV['S3_ACCESS_KEY'],
:aws_secret_access_key => ENV['S3_SECRET_KEY']
}
config.fog_directory = ENV['S3_BUCKET']
end
end

Answer 1

The root issue is that Carrier Wave is expecting your AWS environment variables to be populated but they are not set in your production environment.
I would recommend you look at something like the dotenv gem which can find here. Environment variable housekeeping in multiple environments can be a real pain so it helps to have a tool to facilitate. Dotenv (and others like it) provides more of a turn key approach to this.
Note that the recently introduced secrets.yml for Rails secret management is a nice step in the right direction, but still requires a bit of code/know how to utilize.
In any event, be very careful about how you manage any files with secrets. At a minimum, the file should be in your .gitignore so that you aren't potentially broadcasting your secrets.