How many metric types does Prometheus text format support?

Prometheus definesfour core metric typesin its official exposition format, which are:Counter,Gauge,Histogram, andSummary. These types represent the fundamental building blocks for expressing quantitative measurements of system performance, behavior, and state.

ACounteris a cumulative metric that only increases (e.g., number of requests served).

AGaugerepresents a value that can go up and down, such as memory usage or temperature.

AHistogramsamples observations (e.g., request durations) and counts them in configurable buckets, providing both counts and sum of observed values.

ASummaryis similar to a histogram but provides quantile estimation over a sliding time window along with count and sum metrics.

These four types are theonly officially supported metric typesin the Prometheus text exposition format as defined by the Prometheus data model. Any additional metrics or custom naming conventions are built on top of these core types but do not constitute new types.