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| == PromQL == | == Usage == |
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| '''PromQL''' is a query language built for the Prometheus project. It specializes in time series queries. Consider the use case of monitoring 5xx errors in an [[NGINX]] instance. The below would query all such events: {{{ http_requests_total{status="500"} }}} The below would then query the per-second rate of those events over 5 minutes, demonstrating how time series are a first class citizen of this language: {{{ rate(http_requests_total{status="500"}[5m]) }}} Queries can be functionally combined as shown below, to compute the error rate: {{{ sum(rate(http_requests_total{status="500"}[5m])) / sum(rate(http_requests_total{}[5m])) }}} Furthermore, operators such as division (`/`) are capable of matching left-hand and right-hand vectors, to compute the per-path error rate: {{{ sum by(path) (rate(http_requests_total{status="500"}[5m])) / sum by(path) (rate(http_requests_total{}[5m])) }}} |
See [[Prometheus/PromQL|PromQL]] for the query language. |
Prometheus
Prometheus is a free and open source software project centered on server monitoring and alerting.
Contents
Project
The Prometheus project consists of:
- the Prometheus time series database
the Prometheus web scraper which aggregates metrics from targets into the database
- the built-in web interface for querying the database
- the HTTP API for querying the database, as used by Grafana
a set of exporters which expose metrics from various sources
the Prometheus query language, PromQL
Usage
See PromQL for the query language.