问题
I have followed Ryan Bates railscast on subdomains (http://railscasts.com/episodes/123-subdomains-revised) and have my app working perfectly locally.
I have deployed to heroku but am unable to get my subdomains to work. I have read about custom domains, DNS and CNAME records but I don't think this is relevant because all I am trying to do is test straight on heroku what I was testing locally. So instead of accessing myapp.herokapp.com I would like to be able to access m.myapp.herokuapp.com. Currently when I try this I get the error: There is no app configured at that hostname.
Can anyone offer a solution?
UPDATE:
Whoops, I think this is a duplicate: How to create a subsubdomain for an app on heroku: (e.g. sub.myapp.herokuapp.com)
回答1:
Sub-sub domains aren't possible - you need to be using your own DNS records I'm afraid.
来源：https://stackoverflow.com/questions/17994288/subdomain-with-rails-and-herokuapp