Redmine

Hello Isabela,

I rarely used unicorn but here is my understanding:
When you start unicorn, you start it for one Rails instance on one port (probably 80 or 443).
You cannot have another program or unicorn instance listen to the same port.
So basically, if you want Gitlab and Redmine to be both on the same port, you need to configure nginx(or Apache) as a reverse proxy for the unicorn instances.
If you don't need/want them to run on the same port, you should be able to create an unicorn unicorn config for Redmine, however note that I never heard of someone serving Redmine directly with unicorn (no proxy). People will prefer to go through nginx or Apache as a proxy because it gives more configuration options and can handle larger loads.

Cheers,