Write to prometheus over remote write protocol

prometheus_remote_writer.go

package main

import (
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	"github.com/prometheus/common/model"
	"github.com/prometheus/prometheus/prompb"
	"github.com/golang/snappy"
	"net/http"
	"log"
	"time"
	"io/ioutil"
	"bytes"
)

var (
	exampleMetric = promauto.NewGauge(prometheus.GaugeOpts{
		Name: "example_metric",
		Help: "An example metric",
	})
)

func main() {
	// Set the value of the metric
	exampleMetric.Set(42)

	// Create a Prometheus TimeSeries for the metric
	ts := prompb.TimeSeries{
		Labels: []prompb.Label{
			{
				Name:  "__name__",
				Value: "example_metric",
			},
		},
		Samples: []prompb.Sample{
			{
				Value:     42,
				Timestamp: int64(model.TimeFromUnix(time.Now().Unix())),
			},
		},
	}

	// Create a Prometheus WriteRequest
	req := &prompb.WriteRequest{
		// Timeseries: []*prompb.TimeSeries{ts},
		Timeseries: make([]prompb.TimeSeries, 0, 0),
	}

	req.Timeseries = append(req.Timeseries, ts)

	// Compress and encode the WriteRequest
	data, err := req.Marshal()
	if err != nil {
		log.Fatalf("error marshaling request: %v", err)
	}
	compressed := snappy.Encode(nil, data)

	// Push the WriteRequest to Prometheus
	resp, err := http.Post("http://localhost:9090/api/v1/write", "application/x-protobuf", bytes.NewBuffer(compressed))
	if err != nil {
		log.Fatalf("error sending request: %v", err)
	}
	defer resp.Body.Close()

	// Check the response from Prometheus
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Fatalf("error reading response: %v", err)
	}
	if resp.StatusCode != http.StatusOK {
		log.Fatalf("unexpected status code: %d, body: %s", resp.StatusCode, b)
	}
}