client_golang/examples/exemplars/main.go

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// Copyright 2022 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// A simple example of how to record a latency metric with exemplars, using a fictional id
// as a prometheus label.
package main
import (
"fmt"
"log"
"math/rand"
"net/http"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/collectors"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
func main() {
requestDurations := prometheus.NewHistogram(prometheus.HistogramOpts{
Name: "http_request_duration_seconds",
Help: "A histogram of the HTTP request durations in seconds.",
Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
})
// Create non-global registry.
registry := prometheus.NewRegistry()
// Add go runtime metrics and process collectors.
registry.MustRegister(
collectors.NewGoCollector(),
collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}),
requestDurations,
)
go func() {
for {
// Record fictional latency.
now := time.Now()
requestDurations.(prometheus.ExemplarObserver).ObserveWithExemplar(
time.Since(now).Seconds(), prometheus.Labels{"dummyID": fmt.Sprint(rand.Intn(100000))},
)
time.Sleep(600 * time.Millisecond)
}
}()
// Expose /metrics HTTP endpoint using the created custom registry.
http.Handle(
"/metrics", promhttp.HandlerFor(
registry,
promhttp.HandlerOpts{
EnableOpenMetrics: true,
}),
)
// To test: curl -H 'Accept: application/openmetrics-text' localhost:8080/metrics
log.Fatalln(http.ListenAndServe(":8080", nil))
}