Add support for additional DNS records to Fermyon Cloud's custom domains feature.

[luca-aurelia]

Is your feature request related to a problem? Please describe.

Let's say you have the domain example.com, and that you've set up a service like Google Workspace to receive email at hi@example.com.

If you connect example.com as the domain for a Fermyon Cloud app, it breaks your Google Workspace installation.

Why does this happen?

Google Workspace (and many other services) need TXT, MX, and similar DNS records associated with a domain to function.

Currently, Fermyon Cloud works by adding NS records to your domain, pointing your domain at Fermyon's name servers.

When this happens, your domain registrar's name servers no longer handle your domain, and the additional TXT / MX / etc. records you've set through your registrar no longer take effect.

Describe the solution you'd like

In my experience, other hosting services don't use NS records to connect custom domains. Instead, they usually use CNAME or A records.

Another approach would be to continue using NS records and instead allow users to inform Fermyon's name servers about what additional DNS records should be associated with a domain. This feels a little clunky to me -- it starts requiring you to build out domain registrar type functionality which I don't think makes sense for your business. But it's technically an option.

There might also be some technical way to continue using NS records, but have Fermyon's name servers somehow automatically detect the TXT / MX / etc. records set with your registrar and replicate them. I don't know enough about DNS to say whether this is possible or practical, but might be worth looking into.

Describe alternatives you've considered

You can work around this by hosting your Fermyon Cloud app on a subdomain. For instance, example.com for Google Workspace and app.example.com for your Fermyon Cloud app.

Unfortunately, this means you can't use Fermyon Cloud to host marketing / landing pages where visitors go to example.com and expect to email you at hi@example.com.