Yes—you can safely add a fourth custom URL. The “replace” label appears because the system expects you to submit the entire list of domains each time. To avoid losing any URLs, make sure all four domains—including your existing three—are entered in the form before you submit. Only custom domains omitted from the list will be removed.

More details here:
Updating Custom Domains

Custom domains are available for Basic Cloud deployments. However, this feature relies on a newer backend infrastructure that we’ve recently rolled out. It sounds like your current deployment is on our legacy infrastructure, which does not support custom domains.

We’d be happy to help you migrate your deployment to the new infrastructure so you can enable custom domains. Please note that this migration would involve 30 to 60 minutes of downtime to complete the transition. Let us know if you’d like to proceed!

@mark-robustelli said in Logout with multiple subdomains:

@ext_figuvini after reading your post again, I think I read it differently. The way the SSO logout works is that on logout, FusionAuth calls all the logout urls for each applications. It would seem that you are correct in that creating an application for each subdomain makes sense and would work. (You can create applications through the API so you should be able to automate this.) Can you try this for a few domains and confirm it works?

Your point is correct. Creating a separate application for each subdomain is a reasonable and correct solution.
When a user logs out of the SSO system, FusionAuth will call the logout URLs defined in each configured application in turn. This allows each application to clean up its own session. Pretty good solution

As of July 25, 2023 we now support Unlimited Custom Domains for FusionAuth Cloud! You can read more in this post, on how to add a custom domain.

As of July 25, 2023 we now support Unlimited Custom Domains for FusionAuth Cloud! You can read more in this post, on how to add a custom domain.

As of July 25, 2023 we now support Unlimited Custom Domains for FusionAuth Cloud! You can read more in this post, on how to add a custom domain.