pgnodemx provides a set of functions facilitating the collection of host-node level operational metrics. In particular, pgnodemx has support for capturing metrics related to cgroups (one of the Linux kernel facilities underlying the various Container technologies) and the Kubernetes Downward API.
It also allows capture of certain critical host information from the Linux kernel via virtual files and kernel syscalls.
Through simple SQL queries, you can pull out information about the underlying system that your PostgreSQL instance is running on. It was developed primarily in order to efficiently capture metrics for the purposes of monitoring and alerting in modern DevOps environments.