Hi @anastasiouxrhstos, thank you for pointing out this issue.
This issue has now been resolved in tutor-cairn v19.0.2. Please update to this version to incorporate the fix.
It seems tutor-cairn was adding cairn-postgresql as a dependency even when CAIRN_RUN_POSTGRESQL was set to false. Furthermore, the CAIRN_POSTGRESQL_HOST and CAIRN_POSTGRESQL_PORT configuration settings did not exist. We’ve added those as well now.