@jennifer/prometheus

A Jennifer deck for Prometheus metrics: build counters, gauges, histograms and summaries, render them in the text exposition format (for a /metrics handler, the node_exporter textfile collector or a Pushgateway), and query a Prometheus server's HTTP API.

It was Jennifer's bundled prometheus.j module until 0.27; the surface is the same, so moving over changes only the import:

import "@jennifer/prometheus/" as prometheus;   # was: import "prometheus.j" as prometheus;

Documentation

Install

jvc add @jennifer/prometheus

This vendors the deck to vendor/<scope>/prometheus/. Without jvc, unpack the src/ subtree of a release archive (<scope>-prometheus-<version>.tar.gz) there.

Usage

import "@jennifer/prometheus/" as prometheus;

def m as prometheus.Metric init prometheus.counter("http_requests_total", "Total HTTP requests");
$m = prometheus.observe($m, {"method": "get", "code": "200"}, 1.0);
io.printf("%s", prometheus.render([$m]));

Requirements

Jennifer 0.25.0 or newer, the default jennifer binary: the module imports http (net), so jennifer-tiny cannot load it.

Development

tools/check-all.sh                   # the full gate, as CI runs it
jennifer test src/prometheus_test.j      # the test overlay
tools/check-docs.sh                  # docs against the code
tools/pack.sh dist                   # build the release archive

Licence

LGPL-3.0-only, see LICENSE. Copyright (C) 2026 mplx <[email protected]>.

tools/check-headers.sh checks every source file's SPDX header against deck.toml.