Instrument RoundTripper via middleware (#295)
Instrument RoundTripper via middleware
This commit is contained in:
stuart nelson
Björn Rabenstein
parent
7d9484283e
commit
d300d5cf21
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@ -4,6 +4,7 @@ language: go
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go:
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- 1.6.3
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- 1.7
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- 1.8.1
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script:
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- go test -short ./...
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@ -24,6 +24,11 @@
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// via middleware. Middleware wrappers follow the naming scheme
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// InstrumentHandlerX, where X describes the intended use of the middleware.
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// See each function's doc comment for specific details.
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//
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// Finally, the package allows for an http.RoundTripper to be instrumented via
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// middleware. Middleware wrappers follow the naming scheme
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// InstrumentRoundTripperX, where X describes the intended use of the
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// middleware. See each function's doc comment for specific details.
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package promhttp
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import (
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@ -0,0 +1,95 @@
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// Copyright 2017 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package promhttp
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import (
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"net/http"
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"time"
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"github.com/prometheus/client_golang/prometheus"
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)
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// The RoundTripperFunc type is an adapter to allow the use of ordinary
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// functions as RoundTrippers. If f is a function with the appropriate
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// signature, RountTripperFunc(f) is a RoundTripper that calls f.
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type RoundTripperFunc func(req *http.Request) (*http.Response, error)
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// RoundTrip implements the RoundTripper interface.
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func (rt RoundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) {
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return rt(r)
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}
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// InstrumentRoundTripperInFlight is a middleware that wraps the provided
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// http.RoundTripper. It sets the provided prometheus.Gauge to the number of
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// requests currently handled by the wrapped http.RoundTripper.
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//
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// See the example for ExampleInstrumentRoundTripperDuration for example usage.
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func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripper) RoundTripperFunc {
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return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
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gauge.Inc()
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defer gauge.Dec()
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return next.RoundTrip(r)
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})
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}
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// InstrumentRoundTripperCounter is a middleware that wraps the provided
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// http.RoundTripper to observe the request result with the provided CounterVec.
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// The CounterVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. Partitioning of the CounterVec happens by HTTP status
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// code and/or HTTP method if the respective instance label names are present
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// in the CounterVec. For unpartitioned counting, use a CounterVec with
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// zero labels.
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//
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// If the wrapped RoundTripper panics or returns a non-nil error, the Counter
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// is not incremented.
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//
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// See the example for ExampleInstrumentRoundTripperDuration for example usage.
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func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper) RoundTripperFunc {
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code, method := checkLabels(counter)
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return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
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resp, err := next.RoundTrip(r)
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if err == nil {
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counter.With(labels(code, method, r.Method, resp.StatusCode)).Inc()
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}
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return resp, err
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})
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}
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// InstrumentRoundTripperDuration is a middleware that wraps the provided
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// http.RoundTripper to observe the request duration with the provided ObserverVec.
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// The ObserverVec must have zero, one, or two labels. The only allowed label
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. The Observe method of the Observer in the ObserverVec
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// is called with the request duration in seconds. Partitioning happens by HTTP
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// status code and/or HTTP method if the respective instance label names are
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// present in the ObserverVec. For unpartitioned observations, use an
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// ObserverVec with zero labels. Note that partitioning of Histograms is
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// expensive and should be used judiciously.
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//
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// If the wrapped RoundTripper panics or returns a non-nil error, no values are
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// reported.
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func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper) RoundTripperFunc {
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code, method := checkLabels(obs)
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return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
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start := time.Now()
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resp, err := next.RoundTrip(r)
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if err == nil {
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obs.With(labels(code, method, r.Method, resp.StatusCode)).Observe(time.Since(start).Seconds())
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}
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return resp, err
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})
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}
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@ -0,0 +1,142 @@
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// Copyright 2017 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build go1.8
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package promhttp
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import (
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"context"
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"crypto/tls"
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"net/http"
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"net/http/httptrace"
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"time"
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)
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// InstrumentTrace is used to offer flexibility in instrumenting the available
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// httptrace.ClientTrace hook functions. Each function is passed a float64
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// representing the time in seconds since the start of the http request. A user
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// may choose to use separately buckets Histograms, or implement custom
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// instance labels on a per function basis.
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type InstrumentTrace struct {
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GotConn func(float64)
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PutIdleConn func(float64)
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GotFirstResponseByte func(float64)
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Got100Continue func(float64)
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DNSStart func(float64)
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DNSDone func(float64)
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ConnectStart func(float64)
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ConnectDone func(float64)
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TLSHandshakeStart func(float64)
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TLSHandshakeDone func(float64)
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WroteHeaders func(float64)
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Wait100Continue func(float64)
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WroteRequest func(float64)
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}
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// InstrumentRoundTripperTrace is a middleware that wraps the provided
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// RoundTripper and reports times to hook functions provided in the
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// InstrumentTrace struct. Hook functions that are not present in the provided
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// InstrumentTrace struct are ignored. Times reported to the hook functions are
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// time since the start of the request. Note that partitioning of Histograms
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// is expensive and should be used judiciously.
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//
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// For hook functions that receive an error as an argument, no observations are
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// made in the event of a non-nil error value.
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//
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// See the example for ExampleInstrumentRoundTripperDuration for example usage.
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func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) RoundTripperFunc {
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return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
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start := time.Now()
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trace := &httptrace.ClientTrace{
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GotConn: func(_ httptrace.GotConnInfo) {
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if it.GotConn != nil {
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it.GotConn(time.Since(start).Seconds())
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}
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},
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PutIdleConn: func(err error) {
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if err != nil {
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return
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}
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if it.PutIdleConn != nil {
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it.PutIdleConn(time.Since(start).Seconds())
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}
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},
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DNSStart: func(_ httptrace.DNSStartInfo) {
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if it.DNSStart != nil {
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it.DNSStart(time.Since(start).Seconds())
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}
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},
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DNSDone: func(_ httptrace.DNSDoneInfo) {
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if it.DNSStart != nil {
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it.DNSStart(time.Since(start).Seconds())
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}
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},
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ConnectStart: func(_, _ string) {
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if it.ConnectStart != nil {
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it.ConnectStart(time.Since(start).Seconds())
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}
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},
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ConnectDone: func(_, _ string, err error) {
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if err != nil {
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return
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}
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if it.ConnectDone != nil {
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it.ConnectDone(time.Since(start).Seconds())
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}
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},
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GotFirstResponseByte: func() {
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if it.GotFirstResponseByte != nil {
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it.GotFirstResponseByte(time.Since(start).Seconds())
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}
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},
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Got100Continue: func() {
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if it.Got100Continue != nil {
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it.Got100Continue(time.Since(start).Seconds())
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}
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},
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TLSHandshakeStart: func() {
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if it.TLSHandshakeStart != nil {
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it.TLSHandshakeStart(time.Since(start).Seconds())
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}
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},
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TLSHandshakeDone: func(_ tls.ConnectionState, err error) {
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if err != nil {
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return
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}
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if it.TLSHandshakeDone != nil {
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it.TLSHandshakeDone(time.Since(start).Seconds())
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}
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},
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WroteHeaders: func() {
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if it.WroteHeaders != nil {
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it.WroteHeaders(time.Since(start).Seconds())
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}
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},
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Wait100Continue: func() {
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if it.Wait100Continue != nil {
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it.Wait100Continue(time.Since(start).Seconds())
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}
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},
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WroteRequest: func(_ httptrace.WroteRequestInfo) {
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if it.WroteRequest != nil {
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it.WroteRequest(time.Since(start).Seconds())
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}
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},
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}
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r = r.WithContext(httptrace.WithClientTrace(context.Background(), trace))
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return next.RoundTrip(r)
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})
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}
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@ -0,0 +1,193 @@
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// Copyright 2017 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build go1.8
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package promhttp
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import (
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"log"
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"net/http"
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"testing"
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"time"
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"github.com/prometheus/client_golang/prometheus"
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)
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func TestClientMiddlewareAPI(t *testing.T) {
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client := http.DefaultClient
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client.Timeout = 1 * time.Second
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inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
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Name: "client_in_flight_requests",
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Help: "A gauge of in-flight requests for the wrapped client.",
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})
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counter := prometheus.NewCounterVec(
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prometheus.CounterOpts{
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Name: "client_api_requests_total",
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Help: "A counter for requests from the wrapped client.",
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},
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[]string{"code", "method"},
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)
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dnsLatencyVec := prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "dns_duration_seconds",
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Help: "Trace dns latency histogram.",
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Buckets: []float64{.005, .01, .025, .05},
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},
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[]string{"event"},
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)
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tlsLatencyVec := prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "tls_duration_seconds",
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Help: "Trace tls latency histogram.",
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Buckets: []float64{.05, .1, .25, .5},
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},
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[]string{"event"},
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)
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histVec := prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "request_duration_seconds",
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Help: "A histogram of request latencies.",
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Buckets: prometheus.DefBuckets,
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},
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[]string{"method"},
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)
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prometheus.MustRegister(counter, tlsLatencyVec, dnsLatencyVec, histVec, inFlightGauge)
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trace := &InstrumentTrace{
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DNSStart: func(t float64) {
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dnsLatencyVec.WithLabelValues("dns_start")
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},
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DNSDone: func(t float64) {
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dnsLatencyVec.WithLabelValues("dns_done")
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},
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TLSHandshakeStart: func(t float64) {
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tlsLatencyVec.WithLabelValues("tls_handshake_start")
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},
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TLSHandshakeDone: func(t float64) {
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tlsLatencyVec.WithLabelValues("tls_handshake_done")
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},
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}
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client.Transport = InstrumentRoundTripperInFlight(inFlightGauge,
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InstrumentRoundTripperCounter(counter,
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InstrumentRoundTripperTrace(trace,
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InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
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),
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),
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)
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resp, err := client.Get("http://google.com")
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if err != nil {
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t.Fatalf("%v", err)
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}
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defer resp.Body.Close()
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}
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func ExampleInstrumentRoundTripperDuration() {
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client := http.DefaultClient
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client.Timeout = 1 * time.Second
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inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
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Name: "client_in_flight_requests",
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Help: "A gauge of in-flight requests for the wrapped client.",
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})
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counter := prometheus.NewCounterVec(
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prometheus.CounterOpts{
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Name: "client_api_requests_total",
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Help: "A counter for requests from the wrapped client.",
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},
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[]string{"code", "method"},
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)
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// dnsLatencyVec uses custom buckets based on expected dns durations.
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// It has an instance label "event", which is set in the
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// DNSStart and DNSDonehook functions defined in the
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// InstrumentTrace struct below.
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dnsLatencyVec := prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "dns_duration_seconds",
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Help: "Trace dns latency histogram.",
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Buckets: []float64{.005, .01, .025, .05},
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},
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[]string{"event"},
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)
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// tlsLatencyVec uses custom buckets based on expected tls durations.
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// It has an instance label "event", which is set in the
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// TLSHandshakeStart and TLSHandshakeDone hook functions defined in the
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// InstrumentTrace struct below.
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tlsLatencyVec := prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "tls_duration_seconds",
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Help: "Trace tls latency histogram.",
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Buckets: []float64{.05, .1, .25, .5},
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},
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[]string{"event"},
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)
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// histVec has no labels, making it a zero-dimensional ObserverVec.
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histVec := prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "request_duration_seconds",
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Help: "A histogram of request latencies.",
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Buckets: prometheus.DefBuckets,
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},
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[]string{},
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)
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// Register all of the metrics in the standard registry.
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prometheus.MustRegister(counter, tlsLatencyVec, dnsLatencyVec, histVec, inFlightGauge)
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// Define functions for the available httptrace.ClientTrace hook
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// functions that we want to instrument.
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trace := &InstrumentTrace{
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DNSStart: func(t float64) {
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dnsLatencyVec.WithLabelValues("dns_start")
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},
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DNSDone: func(t float64) {
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dnsLatencyVec.WithLabelValues("dns_done")
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},
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TLSHandshakeStart: func(t float64) {
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tlsLatencyVec.WithLabelValues("tls_handshake_start")
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},
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TLSHandshakeDone: func(t float64) {
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tlsLatencyVec.WithLabelValues("tls_handshake_done")
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},
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}
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// Wrap the default RoundTripper with middleware.
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roundTripper := InstrumentRoundTripperInFlight(inFlightGauge,
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InstrumentRoundTripperCounter(counter,
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InstrumentRoundTripperTrace(trace,
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InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
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),
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),
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)
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// Set the RoundTripper on our client.
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client.Transport = roundTripper
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resp, err := client.Get("http://google.com")
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if err != nil {
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log.Printf("error: %v", err)
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}
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defer resp.Body.Close()
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}
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@ -80,7 +80,7 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) ht
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// names are "code" and "method". The function panics if any other instance
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// labels are provided. Partitioning of the CounterVec happens by HTTP status
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// code and/or HTTP method if the respective instance label names are present
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// in the CounterVec. For unpartitioned observations, use a CounterVec with
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// in the CounterVec. For unpartitioned counting, use a CounterVec with
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// zero labels.
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//
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// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
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