main.go

Documentation: github.com/prometheus/client_golang/examples/random

     1  // Copyright 2015 The Prometheus Authors
     2  // Licensed under the Apache License, Version 2.0 (the "License");
     3  // you may not use this file except in compliance with the License.
     4  // You may obtain a copy of the License at
     5  //
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  // A simple example exposing fictional RPC latencies with different types of
    15  // random distributions (uniform, normal, and exponential) as Prometheus
    16  // metrics.
    17  package main
    18  
    19  import (
    20  	"flag"
    21  	"fmt"
    22  	"log"
    23  	"math"
    24  	"math/rand"
    25  	"net/http"
    26  	"time"
    27  
    28  	"github.com/prometheus/client_golang/prometheus"
    29  	"github.com/prometheus/client_golang/prometheus/collectors"
    30  	"github.com/prometheus/client_golang/prometheus/promhttp"
    31  )
    32  
    33  type metrics struct {
    34  	rpcDurations          *prometheus.SummaryVec
    35  	rpcDurationsHistogram prometheus.Histogram
    36  }
    37  
    38  func NewMetrics(reg prometheus.Registerer, normMean, normDomain float64) *metrics {
    39  	m := &metrics{
    40  		// Create a summary to track fictional inter service RPC latencies for three
    41  		// distinct services with different latency distributions. These services are
    42  		// differentiated via a "service" label.
    43  		rpcDurations: prometheus.NewSummaryVec(
    44  			prometheus.SummaryOpts{
    45  				Name:       "rpc_durations_seconds",
    46  				Help:       "RPC latency distributions.",
    47  				Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
    48  			},
    49  			[]string{"service"},
    50  		),
    51  		// The same as above, but now as a histogram, and only for the
    52  		// normal distribution. The histogram features both conventional
    53  		// buckets as well as sparse buckets, the latter needed for the
    54  		// experimental native histograms (ingested by a Prometheus
    55  		// server v2.40 with the corresponding feature flag
    56  		// enabled). The conventional buckets are targeted to the
    57  		// parameters of the normal distribution, with 20 buckets
    58  		// centered on the mean, each half-sigma wide. The sparse
    59  		// buckets are always centered on zero, with a growth factor of
    60  		// one bucket to the next of (at most) 1.1. (The precise factor
    61  		// is 2^2^-3 = 1.0905077...)
    62  		rpcDurationsHistogram: prometheus.NewHistogram(prometheus.HistogramOpts{
    63  			Name:                        "rpc_durations_histogram_seconds",
    64  			Help:                        "RPC latency distributions.",
    65  			Buckets:                     prometheus.LinearBuckets(normMean-5*normDomain, .5*normDomain, 20),
    66  			NativeHistogramBucketFactor: 1.1,
    67  		}),
    68  	}
    69  	reg.MustRegister(m.rpcDurations)
    70  	reg.MustRegister(m.rpcDurationsHistogram)
    71  	return m
    72  }
    73  
    74  func main() {
    75  	var (
    76  		addr              = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
    77  		uniformDomain     = flag.Float64("uniform.domain", 0.0002, "The domain for the uniform distribution.")
    78  		normDomain        = flag.Float64("normal.domain", 0.0002, "The domain for the normal distribution.")
    79  		normMean          = flag.Float64("normal.mean", 0.00001, "The mean for the normal distribution.")
    80  		oscillationPeriod = flag.Duration("oscillation-period", 10*time.Minute, "The duration of the rate oscillation period.")
    81  	)
    82  
    83  	flag.Parse()
    84  
    85  	// Create a non-global registry.
    86  	reg := prometheus.NewRegistry()
    87  
    88  	// Create new metrics and register them using the custom registry.
    89  	m := NewMetrics(reg, *normMean, *normDomain)
    90  	// Add Go module build info.
    91  	reg.MustRegister(collectors.NewBuildInfoCollector())
    92  
    93  	start := time.Now()
    94  
    95  	oscillationFactor := func() float64 {
    96  		return 2 + math.Sin(math.Sin(2*math.Pi*float64(time.Since(start))/float64(*oscillationPeriod)))
    97  	}
    98  
    99  	// Periodically record some sample latencies for the three services.
   100  	go func() {
   101  		for {
   102  			v := rand.Float64() * *uniformDomain
   103  			m.rpcDurations.WithLabelValues("uniform").Observe(v)
   104  			time.Sleep(time.Duration(100*oscillationFactor()) * time.Millisecond)
   105  		}
   106  	}()
   107  
   108  	go func() {
   109  		for {
   110  			v := (rand.NormFloat64() * *normDomain) + *normMean
   111  			m.rpcDurations.WithLabelValues("normal").Observe(v)
   112  			// Demonstrate exemplar support with a dummy ID. This
   113  			// would be something like a trace ID in a real
   114  			// application.  Note the necessary type assertion. We
   115  			// already know that rpcDurationsHistogram implements
   116  			// the ExemplarObserver interface and thus don't need to
   117  			// check the outcome of the type assertion.
   118  			m.rpcDurationsHistogram.(prometheus.ExemplarObserver).ObserveWithExemplar(
   119  				v, prometheus.Labels{"dummyID": fmt.Sprint(rand.Intn(100000))},
   120  			)
   121  			time.Sleep(time.Duration(75*oscillationFactor()) * time.Millisecond)
   122  		}
   123  	}()
   124  
   125  	go func() {
   126  		for {
   127  			v := rand.ExpFloat64() / 1e6
   128  			m.rpcDurations.WithLabelValues("exponential").Observe(v)
   129  			time.Sleep(time.Duration(50*oscillationFactor()) * time.Millisecond)
   130  		}
   131  	}()
   132  
   133  	// Expose the registered metrics via HTTP.
   134  	http.Handle("/metrics", promhttp.HandlerFor(
   135  		reg,
   136  		promhttp.HandlerOpts{
   137  			// Opt into OpenMetrics to support exemplars.
   138  			EnableOpenMetrics: true,
   139  			// Pass custom registry
   140  			Registry: reg,
   141  		},
   142  	))
   143  	log.Fatal(http.ListenAndServe(*addr, nil))
   144  }
   145
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