CODEWITHSUNDEEP
dnscname
Matt Gaidica
Matt Gaidica

Reputation: 554

Custom Subdomain with CNAME Problem

I am having a bit of a struggle grasping how to use custom domains with my app. Its the common case of having an app that assigns users to subdomains, ex. user.theapp.com and they want to use a CNAME so m.theirsite.com resolves to the application. It seems that most services that do this require you to tell them what your custom domain is, and that just adding a CNAME record doesn't work. Steps:

  1. User creates an account.
  2. We tell them they can make a CNAME entry to yourstuff.theapp.com (which is the current location).
  3. This is my confusion. After 1&2 my custom domain still isnt working.. so once the client makes that CNAME record and provides us with "m.theirsite.com", what special magic do we do with it to make those sites "the same"?

Thank you in advance.

Upvotes: 3

Views: 1431

Answers (1)

Matt Gaidica
Matt Gaidica

Reputation: 554

Our solution was to use PHP/MySQL to solve this. As normal, you should have the external domain/subdomain CNAME'd to your app, however as you will see, the CNAME entry doesn't need to be to the exact subdomain on the app. Next, you will build an area into your database where a user can tell you what external site they have CNAME'd from. At this point, you will perform most of your authentication on the website based on the HTTP host, either grabbing the subdomain and using it as a client, or checking if the HTTP host is in your list of CNAME's and then referencing the client from there.

What the CNAME does is just point to a server location, so if you are using wildcards in your apache configuration, foo.myapp.com resolves to the same location as bar.myapp.com, but in the app can use the host to pull out the subdomain and find the client ("foo" and "bar"). When using a CNAME, like m.mywebsite.com --cnamed--> foo.myapp.com, the application no longer has that client information in the HTTP host, and as we mentioned, the apache wildcard setup (*.myapp.com) just tosses out the subdomain.. so because of this the client must tell us "I will be visiting from m.mywebsite.com, so make that a valid host name for my authentication as well."

Upvotes: 4

Related Questions