This is an unofficial GitLab Pages implementation for GitLab CE, denoted as GCP. Official GitLab Pages is only for GiLab EE, as discussed here and here. Actually, there's already a project aiming at ...
All examples require a SSH_PRIVATE_KEY environment variable set for the Gitlab CI pipeline. This may be set via a "secret variable". See this doc for instructions on creating a new ssh key. Be careful ...