Changing GitLab External_URL - Fails

GitLab Runner (as docker container) unable to perform tasks due to wrong URL addressing when job starts

The exact issue is that when my runner try to run tasks it is trying to address some random symbols URL like: http://87b3409b78:8080/root/myproject and it cannot resolve it, these random symbols also appear in the admin area when checking the URL of the projects. in order to change this number (as i seen in other issues) i need to adjust the file “gitlab.rb” and change the value of “external_url” variable to the correct address, the thing is, when runnign the command “gitlab-ctl reconfigure” the server goes down and the logs doesnt giving much information…

Steps to reproduce

So i have 2 docker containers, 1 for GitLab server and 1 for GitLab Runner
as follows:
GitLab Project (in Admin Area) - Please notice the URL with the random symbols

GitLab Version:


Runner Version:

When trying to execute a job with gitlab-ci.yml file, the pipeline fails with an error:

So, after checking this gitlab issue:

I tried to adjust the “gitlab.rb” file as suggested.
gitlab.rb before the edit:

gitlab.rb after the edit:

After using “gitlab-ctl reconfigure” the server goes down and the logs just print paths of /opt/
and information about gitlab exporter and lots of stuff but i dont see any errors.

*note that if i comment the external_url back, the server can go up healthily.

how do i solve it?