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opentelemetry-go/example/prometheus/main.go

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// Copyright 2019, OpenTelemetry 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.
package main
import (
"context"
"log"
"net/http"
"time"
"go.opentelemetry.io/otel/api/global"
"go.opentelemetry.io/otel/api/key"
"go.opentelemetry.io/otel/api/metric"
"go.opentelemetry.io/otel/exporter/metric/prometheus"
sdkmetric "go.opentelemetry.io/otel/sdk/metric"
"go.opentelemetry.io/otel/sdk/metric/batcher/defaultkeys"
"go.opentelemetry.io/otel/sdk/metric/controller/push"
"go.opentelemetry.io/otel/sdk/metric/selector/simple"
)
var (
fooKey = key.New("ex.com/foo")
barKey = key.New("ex.com/bar")
lemonsKey = key.New("ex.com/lemons")
)
func initMeter() *push.Controller {
selector := simple.NewWithExactMeasure()
exporter, err := prometheus.NewExporter(prometheus.Options{})
if err != nil {
log.Panicf("failed to initialize metric stdout exporter %v", err)
}
// Prometheus needs to use a stateful batcher since counters (and histogram since they are a collection of Counters)
// are cumulative (i.e., monotonically increasing values) and should not be resetted after each export.
//
// Prometheus uses this approach to be resilient to scrape failures.
// If a Prometheus server tries to scrape metrics from a host and fails for some reason,
// it could try again on the next scrape and no data would be lost, only resolution.
//
// Gauges (or LastValues) and Summaries are an exception to this and have different behaviors.
batcher := defaultkeys.New(selector, sdkmetric.NewDefaultLabelEncoder(), true)
pusher := push.New(batcher, exporter, time.Second)
pusher.Start()
go func() {
_ = http.ListenAndServe(":2222", exporter)
}()
global.SetMeterProvider(pusher)
return pusher
}
func main() {
defer initMeter().Stop()
meter := global.MeterProvider().Meter("ex.com/basic")
oneMetric := meter.NewFloat64Gauge("ex.com.one",
metric.WithKeys(fooKey, barKey, lemonsKey),
metric.WithDescription("A gauge set to 1.0"),
)
measureTwo := meter.NewFloat64Measure("ex.com.two", metric.WithKeys(key.New("A")))
measureThree := meter.NewFloat64Counter("ex.com.three")
commonLabels := meter.Labels(lemonsKey.Int(10), key.String("A", "1"), key.String("B", "2"), key.String("C", "3"))
notSoCommonLabels := meter.Labels(lemonsKey.Int(13))
ctx := context.Background()
meter.RecordBatch(
ctx,
commonLabels,
oneMetric.Measurement(1.0),
measureTwo.Measurement(2.0),
measureThree.Measurement(12.0),
)
meter.RecordBatch(
ctx,
notSoCommonLabels,
oneMetric.Measurement(1.0),
measureTwo.Measurement(2.0),
measureThree.Measurement(22.0),
)
time.Sleep(5 * time.Second)
meter.RecordBatch(
ctx,
commonLabels,
oneMetric.Measurement(13.0),
measureTwo.Measurement(12.0),
measureThree.Measurement(13.0),
)
time.Sleep(100 * time.Second)
}