Restrict username allowed characters

Hello and thanks for reading this :wave:

Talking about this setup :slight_smile:

We noticed a problem.
Univention self-service allows more special characters in the username then Cloudron does.
https://docs.cloudron.io/user-management/#valid-usernames

The following characters are allowed in usernames:

  • Alphanumeric characters
  • โ€˜.โ€™ (dot)
  • โ€˜-โ€™ (hyphen)

Now I am looking for a way to restrict the username creation.
While searching I found this blog article:

But after reading this, it does not read like it would do what I need.

Looking forward to read some feedback.

Cheers,
Elias :beers: