Prometheus’s data model

Prometheus’s data model is – in my opinion – straightforward. It has three main data types that are all built on each other: metrics, time series, and samples.

Metrics

Metrics are the fundamental Prometheus data type. After all, Prometheus is a metrics-focused observability tool.

Every metric has – at a minimum – a name that identifies it. This name can contain letters, digits, underscores, and/or colons. To be valid, it must match the [a-zA-Z_:][a-zA-Z0-9_:]* regex.

Additionally, metrics may also include a HELP text and a TYPE field. These are optional but highly recommended to improve usability.

A full metric that’s been exposed to Prometheus may look like this:

# HELP mastering_prometheus_readers_total Number of readers of this book
# TYPE mastering_prometheus_readers_total counter
mastering_prometheus_readers_total 123467890

The HELP line just provides some arbitrary information on what...