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Monitoring Go Applications with Prometheus

Professional

You can instrument your Go application with the official Prometheus Go client library and let the Glouton agent scrape its /metrics endpoint.

Install the client library

go get github.com/prometheus/client_golang/prometheus
go get github.com/prometheus/client_golang/prometheus/promhttp

Minimal example

The snippet below defines a counter and exposes it on http://localhost:8080/metrics:

package main

import (
  "net/http"

  "github.com/prometheus/client_golang/prometheus"
  "github.com/prometheus/client_golang/prometheus/promauto"
  "github.com/prometheus/client_golang/prometheus/promhttp"
)

var requestsTotal = promauto.NewCounter(prometheus.CounterOpts{
  Name: "myapp_requests_total",
  Help: "Total number of processed requests.",
})

func main() {
  http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    requestsTotal.Inc()
    w.Write([]byte("Hello"))
  })
  http.Handle("/metrics", promhttp.Handler())
  http.ListenAndServe(":8080", nil)
}

Scrape with Glouton

Configure Glouton to scrape your application by adding the following to /etc/glouton/conf.d/50-prometheus-metrics.conf:

metric:
  prometheus:
    targets:
      - url: "http://localhost:8080/metrics"
        name: "my_go_application"
        allow_metrics:
          - "myapp_requests_total"

Restart the agent to apply the configuration. See Prometheus Monitoring for the full list of options, including Docker label auto-discovery and Kubernetes annotations.

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