Here is what I have so far:

SSH as root user in root folder:

sudo wget -O /etc/yum.repos.d/openproject.repo \ https://dl.packager.io/srv/opf/openproject/stable/10/installer/el/7.repo

Install using:

sudo yum install openproject

Then configure with the following, but skip Apache installation (!):

sudo openproject configure

or

sudo openproject reconfigure

If you already have a local Apache2 installed that the OpenProject package may not control, we will use our existing Apache2 and Virtual Host to function as the web server forwarding to OpenProject's internal server listening at localhost:6000 by proxying.

When installing with an existing Apache2, OpenProject suggests using the following installation wizard templates for guidance on how to set up the integration - https://github.com/pkgr/addon-apache2/tree/master/conf

But to access a Ruby app via the Virtual Host, you still need to have Phusion Passenger installed first. On a Centos 7 VPS with cPanel/WHM you can not do this with the methods the Phusion Passenger website suggests.

If your Apache is configured via cPanel/WHM, use the following instruction to install Passenger:

https://www.liquidweb.com/kb/using-passenger-cpanel-centos-7/

Make sure you have EasyApache4:

ls /etc/cpanel/ea4/is_ea4

Then add the mod_passenger option plus supporting packages into your EasyApache 4 configuration:

yum -y update; yum -y install ea-ruby24-mod_passenger ea-ruby24-ruby-devel ea-apache24-devel

There is one more item we need in order to install Ruby applications easily:

scl enable ea-ruby24 'gem install bundle'

Confirm that mod_passenger, the connector to Apache, was installed properly:

httpd -M | grep passenger

Make sure that Passenger itself is set up and working:

scl enable ea-ruby24 'passenger-config validate-install'

All looks good. Continue follow instructions here how to configure your Ruby app:

https://www.liquidweb.com/kb/using-passenger-cpanel-centos-7/

Or manually:

https://www.phusionpassenger.com/library/deploy/apache/deploy/ruby/

Check if OpenProject is actually installed:

sudo openproject run check

There was also this "test" somewhere, with zero explanation what it was supposed to do:

curl localhost:6000

It outputs an entire html page, openproject_initializer - never seen that before in SSH...

This is probably the page I want to see in my browser, but I still have no idea how to make that happen. The cPanel/WHM way to deploy a Ruby application is via the cPanel Application Manager, which you may have to activate first via WHM if it doesn't show up.

I want OpenProject to appear on a subfolder (?) of my main website, like mainwebsite.com/openproject . Application Manager asks me to 'enter the path to your application’s source code directory, relative to the home directory' - which directory is that? I have tried several variations, with or without /, different domains, etc. Still getting nothing on mainwebsite.com/openproject

Stuck again. No idea how to troubleshoot this. What else to check? Has anyone done this? Can anyone solve this puzzle?