I just installed the shopify_api gem and generated a placeholder app.
Once I visit localhost:3000 and enter my stores url I get the following in in HomeController#index error:
ActiveResource::ForbiddenAccess .
I have determined it is coming from this line in home_controller.rb
@orders = ShopifyAPI::Order.find(:all)
Commenting this out solves the issue.
It looks like some kind of permission is not working with the orders.
My domain in my app settings matches localhost:3000.
Have you followed the Getting Started steps at in the README for the shopify_api gem, because until you do ShopifyAPI::Base.activate_session(session) your request won’t have the required authentication. This is why you are getting a 403 (i.e. ForbiddenAccess) error response.
In this case you are listing orders, in which case you need the read_orders scope if you are using oauth2 authentication. See the Authentication page in the API docs for a list of scopes and where they are needed.
Edit: Realized that 403 response is for missing access (i.e. scope), rather than 401 which would be authentication.