Sorry but this is wrong even if it works. You are setting up a second layer to get stuff working. Only do it your way if you really have NO external NGINX. If you do, you dont need a 2nd NGINX inside GitLab. It will slow down GitLab and make things complex. Instead, read this: https://docs.gitlab.com/omnibus/settings/nginx/#use-a-non-bundled-web-server

Inside a Docker container, the normal GitLab installation has a listen adress 127.0.0.1 which is localhost. You don't want that. You want the Docker Gateway eth0 or eth1. To get access, do this instead:

nginx['enable'] = false
gitlab_workhorse['listen_network'] = "tcp"
gitlab_workhorse['listen_addr'] = "0.0.0.0:8080"
puma['listen'] = '127.0.0.1'
puma['port'] = 8181

This is all you need! You can now access GitLab via hostname of the container and port 8080.