I have installed openproject using debian jessie and now I can access openproject using http://localhost/
I want to change the URL to http://192.168.1.100/openproject instead. I tried searching online but it seems hard to find a solution. Any help is appreciated!

I’ve done it once installed by adding:

rails_relative_url_root: “/openproject”*

in configuration.yml file at /opt/openproject/config folder

Francesc Estanyol Casals already gave the correct answer.

If you installed OpenProject using the package install, you can also issue

as root:

openproject config:set SERVER_PATH_PREFIX=/openproject

then
as root:

openproject configure

This will set the envelope variable and rerun configuration of your openproject installation.

This was a great help to me except it missed one detail: you need the relative url to be included in your Apache proxy statement, along the lines of:

ProxyPass /openproject/ http://127.0.0.1:6000/openproject/ retry=0
ProxyPassReverse /openproject/ http://127.0.0.1:6000/openproject/