[Feature Request]: Remove the distinction between subdirectory and subdomain installations

[johnbillion]

Is your feature request related to a problem?

I believe there is now almost no functional distinction between a subdirectory installation and a subdomain installation of Multisite. When setting up a network from the Tools -> Setup Network menu, this option sets the value of the SUBDOMAIN_INSTALL constant.

I just had a very quick scan through WordPress core and it looks like the wp-signup.php screen varies depending on this constant, but I can't see anything else of great consequence.

Describe the desired solution

Ideally there would be no distinction between an installation that uses subdirectories, subdomains, or mapped domains. Essentially everything can be treated as a mapped domain.

Altis Cloud removes this distinction for this reason: https://github.com/humanmade/altis-cms/blob/master/inc/add_site_ui/namespace.php.

Describe the alternatives that you have considered

.

Additional context

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[felixarntz]

Also worth noting the extra-hidden option to use regular domains (not subdomains).

It's so strange to me that this is not intuitively available in WordPress UI. Right now you can only do that by creating a subdomain site first, and then later changing the domain in the options to be its own domain. Would be great if this could be immediately available when you add a new site.

I think some of the concerns in the past have been that it's not trivial, because it would only work if you set up routing for the new domain. But I would argue that is the same for subdomains - unless you have a wildcard subdomain setup, which many Multisite networks do not.

[lloc]

Thanks for bringing this up, @johnbillion, and for the thoughtful input, @felixarntz. You both make excellent points (as always 😉). I’ve also noticed how the distinction between subdirectory and subdomain installs feels increasingly unnecessary.

The idea of treating everything as a mapped domain makes a lot of sense. I really like how Altis approaches this, it’s a great reference for what’s possible. If we move in that direction, we should also look into improving the domain handling UI. As you pointed out, Felix, having to create a subdomain site first and then change the domain later isn’t ideal; definitely something worth simplifying.

In my personal multi-network setup, I’ve actually mapped entire networks to domains and use subdirectories for the subsites — so this is definitely a topic I care about too.