Prometheus (Stats)

• Introduction
• Creating the exporter
• Running Prometheus
• Viewing your metrics
• Project link

Introduction

Prometheus is a monitoring system that collects metrics, by scraping exposed endpoints at regular intervals, evaluating rule expressions. It can also trigger alerts if certain conditions are met.

OpenCensus Go allows exporting stats to Prometheus by means of the Prometheus package contrib.go.opencensus.io/exporter/prometheus

Creating the exporter

To create the exporter, we’ll need to:

• Import and use the Prometheus exporter package
• Define a namespace that will uniquely identify our metrics when viewed on Prometheus
• Expose a port on which we shall run a /metrics endpoint
• With the defined port, we’ll need a Promethus configuration file so that Prometheus can scrape from this endpoint

  import "contrib.go.opencensus.io/exporter/prometheus"
  
  // Then create the actual exporter
  pe, err := prometheus.NewExporter(prometheus.Options{
      Namespace: "demo",
  })
  if err != nil {
      log.Fatalf("Failed to create the Prometheus exporter: %v", err)
  }

An instance of the Prometheus exporter implements http.Handler so we’ll need to expose it on our port of choice say “:8888”

package main

import (
	"log"
	"net/http"

	"contrib.go.opencensus.io/exporter/prometheus"
	"go.opencensus.io/stats/view"
)

func main() {
	pe, err := prometheus.NewExporter(prometheus.Options{
		Namespace: "demo",
	})
	if err != nil {
		log.Fatalf("Failed to create Prometheus exporter: %v", err)
	}

	go func() {
		mux := http.NewServeMux()
		mux.Handle("/metrics", pe)
		if err := http.ListenAndServe(":8888", mux); err != nil {
			log.Fatalf("Failed to run Prometheus /metrics endpoint: %v", err)
		}
	}()
}

and then for our corresponding prometheus.yaml file:

global:
  scrape_interval: 10s

  external_labels:
    monitor: 'demo'

scrape_configs:
  - job_name: 'demo'

    scrape_interval: 10s

    static_configs:
      - targets: ['localhost:8888']

Running Prometheus

And then run Prometheus with your configuration

prometheus --config.file=prometheus.yaml

Viewing your metrics

Please visit http://localhost:9090

Project link

You can find out more about the Prometheus project at https://prometheus.io/