cloudinfra project is a very special project intended to hold infrastructure relating to running the rest of Cloud VPS. Access to it is restricted under Help:Access policies.
Types of instances it contains currently:
These instances serve the rest of Cloud VPS with NTP updates.
These instances serve the rest of Cloud VPS with outbound mail handling.
These instances serve as the puppet master for projects that do not use project-local puppet masters.
These instances contain MariaDB databases that keep state for important Cloud VPS infrastructure hosted within Cloud VPS itself. Currently that only includes the Puppet ENC database (labspuppet).
We don't yet have regular backups of that cluster (phab:T301640). :(
This is a small project-local puppetmaster that keeps secrets (such as cumin ssh keys and enc database passwords) for some of the cloudinfra instances.
These instances host the Puppet ENC API that was previously hosted on the cloud-puppetmasters.
This project also has an important role with regards to DNS. See Portal:Cloud_VPS/Admin/DNS for more info.
The equivalent of this project in the codfw1dev deployment is called cloudinfra-codfw1dev, and has the same role within the deployment.