Inherited an CI project and am pretty lost with it.

Hello!

I inherited some old(?) CI project against my will and now I need to make some updates but I'm pretty lost with the configuration.

A little background: I know PHP and I've been using Drupal for like 10 or so years. I've done stuff with Joomla, WP, Symfony and plain PHP. I'd like to think myself as a PHP professional. I have also inherited stuff before that I had no prior experience with and always managed to get by.

But now I'm stuck with this. This is running live currently and we're at the planning stage of an new system but before we get that going, customer wants some changes to their CI application. There's no documentation to go by.

I have downloaded the code from live server to my local environment running Ddev based Docker setup. This setup has worked for Symfony, Drupal, Joomla & WP sites, so I'm assuming it should be fine for CI app as well.

I also have gone through the configs in system/application/config and tried to make necessary changes for local Docker env. I'm pretty sure I've got most things configured, since I do get DB connection and can see configs with xdebug. The system is also redirecting me to /login path which makes me think that atleast something works.

However, I'm completely stuck with some routing troubles. 

No matter what URL I try to access, I get redirected to /login with 404 error. In my log I see this:

Code:

ERROR - 2019-03-29 00:57:01 --> Severity: Notice  --> Only variables should be passed by reference /var/www/html/system/codeigniter/Common.php 150
DEBUG - 2019-03-29 00:57:01 --> Config Class Initialized
ERROR - 2019-03-29 00:57:01 --> Severity: Notice  --> Only variables should be passed by reference /var/www/html/system/codeigniter/Common.php 150
DEBUG - 2019-03-29 00:57:01 --> Hooks Class Initialized
ERROR - 2019-03-29 00:57:01 --> Severity: Notice  --> Only variables should be passed by reference /var/www/html/system/codeigniter/Common.php 150
DEBUG - 2019-03-29 00:57:01 --> URI Class Initialized
ERROR - 2019-03-29 00:57:01 --> Severity: Notice  --> Only variables should be passed by reference /var/www/html/system/codeigniter/Common.php 142
ERROR - 2019-03-29 00:57:16 --> 404 Page Not Found --> q

While debugging system/libraries/Router.php I can see that it tries to access URI "q". So perhaps there's something wrong with url rewriting?

TBH, I have a lot to learn with CI, but it would be easier if I'd get this app up locally to debug more.

From what I've read, CI is pretty loose with how you do stuff so I fear that this app may not have been coded following best practices. 

But if I get this up locally I'm pretty sure I can reverse-engineer how this CI app works.

So as I'm going through the documentation, I would really appreciate any input as to how to get this up and running.

Thanks for any advice.

/ Janne