rails get app root/base url

In my app I have a few APIs that under api domain. Now in one of the API I want to generate a url that pointing to the main domain, say

test.com/blabla...

I tried to use url_for but seems the default root_url or request.host is in api domain. Url_for will make it to be

api.test.com/blabla..

while I want it to be

test.com/blabla...

Url_for can take a parameter

host: ...

to set it to be test.com/, the question is how can I get the root/base url (test.com) for host? root_url or request.host are all api.test.com.

Any ideas? Thanks.

Just so that it's useful to someone else , i came across this today

request.base_url

gives the full path in local as well as on live .

request.domain

gives just the domain name so it sometimes kinda breaks the link while redirecting

According to this you can do request.domain