We don't have to put everything there. We also run the reddit software, an IRC server, a plain old web server that users can ssh into, and a CIFS file server. It's mostly standard highly-scalable free software, and it all runs without an internet connection.

We do sadly have a bit of a JIRA addiction. It's a bad habit that is hard to break. The lock-in is real. Never start down this path.

One nice thing about the free software is that you can clone a fresh VM for a new project. You don't have to purchase anything. Use of a VM solves lots of troubles with access control.