upgrade gitlab 5.0.1 to 7.10.4 on CentOS 6

1. backup
    sudo gitlab-rake gitlab:backup:create

    https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/raketasks/backup_restore.md

   copy /var/opt/gitlab/backups/xxxxx_gitlab_backup.tar to temp directory

2. delete completely

     sudo gitlab-ctl stop
     sudo gitlab-ctl uninstall
     sudo gitlab-ctl cleanse
     sudo gitlab-ctl remove-accounts

    https://forum.gitlab.com/t/complete-uninstall-gitlab-ce-from-ubuntu-14/6232


3. download gitlab-ce-7.10.4~omnibus.1-1.x86_64.rpm

    https://packages.gitlab.com/gitlab/gitlab-ce/packages/el/6/gitlab-ce-7.10.4~omnibus.1-1.x86_64.rpm

4. install
    sudo EXTERNAL_URL="http://gitlab.example.com" rpm -i gitlab-ce-7.10.4~omnibus.1-1.x86_64.rpm

    https://docs.gitlab.com/omnibus/manual_install.html

5. edit /etc/gitlab/gitlab.rb
    external_url
 
6. sudo gitlab-ctl reconfigure

7. check works properly in url

8.
sudo gitlab-ctl stop unicorn
sudo gitlab-ctl stop sidekiq

9. copy backup file in temp directory(1) to /var/opt/gitlab/backups 

   chown git:git /var/opt/gitlab/backups/xxxx_gitlab_backup.tar

10. sudo gitlab-rake gitlab:backup:restore

sudo gitlab-ctl tail

https://docs.gitlab.com/ee/policy/maintenance.html#upgrade-recommendations