I need help with multi tenant app + custom domain

You'll need to provide your users with a DNS target that they add in their domain dashboard.

You can use vhost then to parse the subdomain for incoming requests and get the 'user1' part and do whatever you need to do with it.

You'll need an SSL cert with a wildcard, which can be tricky once you reach over 100+ users. Heroku will manage this for you up to 100 users.

For the management of the multi-tenant aspects, you probably want to use something like Authress, which will solve SSO login and user access management.

For the domain masking, you actually need two pieces:

• a valid TLS cert containing user1.com that you can use to encrypt resources in your app, you'll need an additional cert for every domain you want to serve. This is fairly complicated, so my recommendation is use a TLS provider. We use AWS to request custom certs. But you could roll something with Traefik and LetsEncrypt
• a valid CNAME pointing at your CNAME record which is your app. To set yours up, you need this: https://vercel.com/docs/custom-domains. I have no idea if Vercel supports multiple custom domains, I'm assuming it doesn't out of the box.

I've solved this issue (probably in an unconventional way due to the product needs).

If you're interested:

https://buttondown.email/quill/archive/3ed93ce1-f4cd-4cd8-bae8-1bb4c0bbd73a

https://buttondown.email/quill/archive/2798abf4-a68e-4566-b0d1-e0e6ed77b98d

Hi Eunjae,

I know its not what you were expecting to hear but I strongly recommend leaving the vanity domain feature till much, much later.

I mean I access my business email from https://mail.google.com/mail/u/0/#inbox and its fine. I'm hard pressed to think of an example where my own domain when accessing an app would be a feature worth the effort.

I think @noahwbragg recently solved this with an indie hacker product.

We have a custom solution at https://versoly.com/ but spent 2 years perfecting it.