Node Exporter overview
The Node Exporter is one of the select few exporters maintained by the official Prometheus project, alongside others such as the Blackbox Exporter and the SNMP Exporter. Its purpose is to expose a variety of machine-level metrics pertaining to resources such as CPU, disk, memory, networking, and more.
One of the things I often say to people asking whether we have some system-level metric in Prometheus is, “If it’s in /proc, the Node Exporter can get it.”
What’s /proc?
In Linux systems, a /proc directory exists that contains a plethora of information about the state of the machine. The Linux kernel documentation describes it thusly:
The proc file system acts as an interface to internal data structures in the kernel. It can be used to obtain information about the system and to change certain kernel parameters at runtime (sysctl).
The Node Exporter primarily retrieves data through the /proc pseudo-filesystem. There are...
