client_golang/prometheus/promhttp/instrument_client_test.go

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// Copyright 2017 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.
package promhttp
import (
"context"
"fmt"
"log"
"net/http"
"net/http/httptest"
"testing"
"time"
"github.com/prometheus/client_golang/prometheus"
)
func makeInstrumentedClient() (*http.Client, *prometheus.Registry) {
client := http.DefaultClient
client.Timeout = 1 * time.Second
reg := prometheus.NewRegistry()
inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
Name: "client_in_flight_requests",
Help: "A gauge of in-flight requests for the wrapped client.",
})
counter := prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "client_api_requests_total",
Help: "A counter for requests from the wrapped client.",
},
[]string{"code", "method"},
)
dnsLatencyVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "dns_duration_seconds",
Help: "Trace dns latency histogram.",
Buckets: []float64{.005, .01, .025, .05},
},
[]string{"event"},
)
tlsLatencyVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "tls_duration_seconds",
Help: "Trace tls latency histogram.",
Buckets: []float64{.05, .1, .25, .5},
},
[]string{"event"},
)
histVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "request_duration_seconds",
Help: "A histogram of request latencies.",
Buckets: prometheus.DefBuckets,
},
[]string{"method"},
)
reg.MustRegister(counter, tlsLatencyVec, dnsLatencyVec, histVec, inFlightGauge)
trace := &InstrumentTrace{
DNSStart: func(t float64) {
dnsLatencyVec.WithLabelValues("dns_start").Observe(t)
},
DNSDone: func(t float64) {
dnsLatencyVec.WithLabelValues("dns_done").Observe(t)
},
TLSHandshakeStart: func(t float64) {
tlsLatencyVec.WithLabelValues("tls_handshake_start").Observe(t)
},
TLSHandshakeDone: func(t float64) {
tlsLatencyVec.WithLabelValues("tls_handshake_done").Observe(t)
},
}
client.Transport = InstrumentRoundTripperInFlight(inFlightGauge,
InstrumentRoundTripperCounter(counter,
InstrumentRoundTripperTrace(trace,
InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
),
),
)
return client, reg
}
func TestClientMiddlewareAPI(t *testing.T) {
client, reg := makeInstrumentedClient()
backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
}))
defer backend.Close()
resp, err := client.Get(backend.URL)
if err != nil {
t.Fatal(err)
}
defer resp.Body.Close()
mfs, err := reg.Gather()
if err != nil {
t.Fatal(err)
}
if want, got := 3, len(mfs); want != got {
t.Fatalf("unexpected number of metric families gathered, want %d, got %d", want, got)
}
for _, mf := range mfs {
if len(mf.Metric) == 0 {
t.Errorf("metric family %s must not be empty", mf.GetName())
}
}
}
func TestClientMiddlewareAPIWithRequestContext(t *testing.T) {
client, reg := makeInstrumentedClient()
backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
}))
defer backend.Close()
req, err := http.NewRequest("GET", backend.URL, nil)
if err != nil {
t.Fatalf("%v", err)
}
// Set a context with a long timeout.
ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
defer cancel()
req = req.WithContext(ctx)
resp, err := client.Do(req)
if err != nil {
t.Fatal(err)
}
defer resp.Body.Close()
mfs, err := reg.Gather()
if err != nil {
t.Fatal(err)
}
if want, got := 3, len(mfs); want != got {
t.Fatalf("unexpected number of metric families gathered, want %d, got %d", want, got)
}
for _, mf := range mfs {
if len(mf.Metric) == 0 {
t.Errorf("metric family %s must not be empty", mf.GetName())
}
}
}
func TestClientMiddlewareAPIWithRequestContextTimeout(t *testing.T) {
client, _ := makeInstrumentedClient()
// Slow testserver responding in 100ms.
backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
time.Sleep(100 * time.Millisecond)
w.WriteHeader(http.StatusOK)
}))
defer backend.Close()
req, err := http.NewRequest("GET", backend.URL, nil)
if err != nil {
t.Fatalf("%v", err)
}
// Set a context with a short timeout.
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
defer cancel()
req = req.WithContext(ctx)
_, err = client.Do(req)
if err == nil {
t.Fatal("did not get timeout error")
}
if want, got := fmt.Sprintf("Get %s: context deadline exceeded", backend.URL), err.Error(); want != got {
t.Fatalf("want error %q, got %q", want, got)
}
}
func ExampleInstrumentRoundTripperDuration() {
client := http.DefaultClient
client.Timeout = 1 * time.Second
inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
Name: "client_in_flight_requests",
Help: "A gauge of in-flight requests for the wrapped client.",
})
counter := prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "client_api_requests_total",
Help: "A counter for requests from the wrapped client.",
},
[]string{"code", "method"},
)
// dnsLatencyVec uses custom buckets based on expected dns durations.
// It has an instance label "event", which is set in the
// DNSStart and DNSDonehook functions defined in the
// InstrumentTrace struct below.
dnsLatencyVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "dns_duration_seconds",
Help: "Trace dns latency histogram.",
Buckets: []float64{.005, .01, .025, .05},
},
[]string{"event"},
)
// tlsLatencyVec uses custom buckets based on expected tls durations.
// It has an instance label "event", which is set in the
// TLSHandshakeStart and TLSHandshakeDone hook functions defined in the
// InstrumentTrace struct below.
tlsLatencyVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "tls_duration_seconds",
Help: "Trace tls latency histogram.",
Buckets: []float64{.05, .1, .25, .5},
},
[]string{"event"},
)
// histVec has no labels, making it a zero-dimensional ObserverVec.
histVec := prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "request_duration_seconds",
Help: "A histogram of request latencies.",
Buckets: prometheus.DefBuckets,
},
[]string{},
)
// Register all of the metrics in the standard registry.
prometheus.MustRegister(counter, tlsLatencyVec, dnsLatencyVec, histVec, inFlightGauge)
// Define functions for the available httptrace.ClientTrace hook
// functions that we want to instrument.
trace := &InstrumentTrace{
DNSStart: func(t float64) {
dnsLatencyVec.WithLabelValues("dns_start").Observe(t)
},
DNSDone: func(t float64) {
dnsLatencyVec.WithLabelValues("dns_done").Observe(t)
},
TLSHandshakeStart: func(t float64) {
tlsLatencyVec.WithLabelValues("tls_handshake_start").Observe(t)
},
TLSHandshakeDone: func(t float64) {
tlsLatencyVec.WithLabelValues("tls_handshake_done").Observe(t)
},
}
// Wrap the default RoundTripper with middleware.
roundTripper := InstrumentRoundTripperInFlight(inFlightGauge,
InstrumentRoundTripperCounter(counter,
InstrumentRoundTripperTrace(trace,
InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
),
),
)
// Set the RoundTripper on our client.
client.Transport = roundTripper
resp, err := client.Get("http://google.com")
if err != nil {
log.Printf("error: %v", err)
}
defer resp.Body.Close()
}