We plan to provide conan as a part of our qtbase builds. We should define if we are allowing conan to use a default "service credentials" or the customer should obtain one and store that in a specific file for the whole thing to work? 

If the customer has to provide this then "conan login" should be used then username and password for the service should be provided in the build env or stored as env variable in the GitLab CI (or similar).