how can i secure the dagit ui using username/password credentials

nothing built in to dagit to handle this for you at the moment, what we’ve seen some people in the community do successfully is put dagit behind an identity aware proxy https://cloud.google.com/iap for example

we used an apache2 module called mod_auth_mellon to do the same. not awesome (mainly no HA story) but it works. https://github.com/latchset/mod_auth_mellon