I followed this documentation and created a hook in the directory : /opt/gitlab/embedded/service/gitlab-shell/hooks, but it didn't work.
Then as explain to this question I tried to copy the hook to this directory : /opt/gitlab/embedded/service/gitaly-ruby/git-hooks, it didn't work neither.
Finally I tried this one : /opt/gitlab/embedded/service/gitaly-ruby/gitlab-shell/hooks but same result.
Does anyone know where should I create it and if there is log to troubleshoot ?
Thanks
I finally found how to make it work. I had to change the location in /etc/gitlab/gitlab.rb by uncommenting and editing the line beginning gitlab_shell['custom_hooks_dir'] = ..., then running sudo gitlab-ctl reconfigure