inspector-prometheus

Typescript metric reporter for prometheus.

This library is made for inspector-metrics node module and is meant to be used with nodejs.

All metrics from the inspector-metrics library can be pushed to a pushgateway or be exposed with a custom /metrics endpoint in your application.

install

npm install --save inspector-prometheus

basic usage

example.ts

import {
    MetricRegistry,
} from "inspector-metrics";

import {
    PrometheusMetricReporter,
} from "inspector-prometheus";

// contains all metrics
const registry = new MetricRegistry();
// exposes the metrics
const reporter = new PrometheusMetricReporter({});

// register the registry within the reporter
reporter.addMetricRegistry(registry);

// common tags for all metrics
const tags = new Map();
tags.set("app_version", "1.0.0");
reporter.setTags(tags);

// a simple request timer used to report response latencies
const requests: Timer = registry.newTimer("requests");
// custom metric tag
requests.setTag("host", "127.0.0.3");

// some server implementation - could be anything KOA, Express, HAPI ...
const server = new Hapi.Server({ host: "0.0.0.0", port: 8080 });

// '/metrics' is the standard route used by prometheus ...
server.route({
    method: "GET",
    path: "/metrics",
    handler(request, h) {
        console.log("reporting metrics");
        return h.response(reporter.getMetricsString())
            .code(200)
            .type("text/plain");
    },
});

// starts the server
server.start();

/etc/prometheus/config.yml

global:
  scrape_interval:     15s
  evaluation_interval: 30s

scrape_configs:
- job_name: test-app
  metrics_path: /metrics
  static_configs:
    - targets:
      - localhost:8080

example metrics report

# HELP requests request durations for some endpoint
# TYPE requests summary
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.01"} 0
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.05"} 0
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.5"} 999936
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.75"} 999936
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.9"} 1000192
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.95"} 1000192
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.98"} 1999872
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.99"} 2000128
requests{app_version="1.0.0",host="127.0.0.3",quantile="0.999"} 4000000
requests_count{app_version="1.0.0",host="127.0.0.3"} 362
requests_sum{app_version="1.0.0",host="127.0.0.3"} 283998208

reporting options for PrometheusMetricReporter

import {
    PrometheusMetricReporter,
} from "inspector-prometheus";

const reporter = new PrometheusMetricReporter({
    includeTimestamp: true,
    emitComments: true,
    useUntyped: false,
});

report metrics with pushgateway

import ...; // like in the example above

import {
    PrometheusMetricReporter,
    PushgatewayMetricReporter,
} from "inspector-prometheus";

// contains all metrics
const registry = new MetricRegistry();
// exposes the metrics
const reporter = new PrometheusMetricReporter({});

// register the registry within the reporter
reporter.addMetricRegistry(registry);

const pushReporter = new PushgatewayMetricReporter({
    reporter,

    host: "localhost",
    port: 9091,
    job: "pushgateway",
    instance: "127.0.0.4",
});

// start reporting
await pushReporter.start();

local dev

setup playground

Have a look at playground/playground.ts to see what is reported to the prometheus server.
To let it run in a fully provisioned environment do the following:

execute npm i
execute test-env/boot.sh - builds the docker images and starts the services
start the playground app by executing ./playground.sh
navigate to localhost:3000 in the browser
click on dashboard Playground Dashboard and see the reporter work

Example Dashboard

compile & test with different nodejs versions

build docker images:

docker-compose build

run tests:

docker-compose run node6
docker-compose run node7
docker-compose run node8
docker-compose run node9
docker-compose run node10
docker-compose run node11

License

MIT