Increase minimum required Go version to 1.9

This allows us to simplify a bunch of code while still supporting the
last four Go minor versions.

We have also run into minor annoyances a couple of times by now to
keep supporting 1.7 and 1.8.

It's time to pull the plug!

Signed-off-by: Bjoern Rabenstein <bjoern@rabenste.in>

.travis.yml

@@ -1,15 +1,13 @@
 language: go
 
 go:
-  - 1.7.x # See README.md for current minimum version.
+  - 1.9.x # See README.md for current minimum version.
-  - 1.8.x
-  - 1.9.x
   - 1.10.x
   - 1.11.x
   - 1.12.x
 
 script:
   - make check_license unused test-short
-  - if [[ ! $TRAVIS_GO_VERSION =~ ^1\.(7|8|9)\.[x0-9]+$ ]]; then make lint; fi
+  - if [[ ! $TRAVIS_GO_VERSION =~ ^1\.9\.[x0-9]+$ ]]; then make lint; fi
-  # style is only checked against the latest supported Go version.
+  # Style is only checked against the latest supported Go version.
   - if [[ $TRAVIS_GO_VERSION =~ ^1\.(12)\. ]]; then make style; fi

README.md

@@ -9,7 +9,7 @@ This is the [Go](http://golang.org) client library for
 instrumenting application code, and one for creating clients that talk to the
 Prometheus HTTP API.
 
-__This library requires Go1.7 or later.__
+__This library requires Go1.9 or later.__
 
 ## Important note about releases, versioning, tagging, and stability
 

api/client.go

@@ -11,8 +11,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.7
-
 // Package api provides clients for the HTTP APIs.
 package api
 

api/client_test.go

@@ -11,8 +11,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.7
-
 package api
 
 import (

api/prometheus/v1/api.go

@@ -11,8 +11,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.7
-
 // Package v1 provides bindings to the Prometheus HTTP API v1:
 // http://prometheus.io/docs/querying/api/
 package v1

api/prometheus/v1/api_test.go

@@ -11,8 +11,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.7
-
 package v1
 
 import (

prometheus/promhttp/delegator.go

@@ -74,6 +74,7 @@ type closeNotifierDelegator struct{ *responseWriterDelegator }
 type flusherDelegator struct{ *responseWriterDelegator }
 type hijackerDelegator struct{ *responseWriterDelegator }
 type readerFromDelegator struct{ *responseWriterDelegator }
+type pusherDelegator struct{ *responseWriterDelegator }
 
 func (d closeNotifierDelegator) CloseNotify() <-chan bool {
 	//lint:ignore SA1019 http.CloseNotifier is deprecated but we don't want to
@@ -198,3 +199,31 @@ func init() {
 		}{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
 	}
 }
+
+func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator {
+	d := &responseWriterDelegator{
+		ResponseWriter:     w,
+		observeWriteHeader: observeWriteHeaderFunc,
+	}
+
+	id := 0
+	//lint:ignore SA1019 http.CloseNotifier is deprecated but we don't want to
+	//remove support from client_golang yet.
+	if _, ok := w.(http.CloseNotifier); ok {
+		id += closeNotifier
+	}
+	if _, ok := w.(http.Flusher); ok {
+		id += flusher
+	}
+	if _, ok := w.(http.Hijacker); ok {
+		id += hijacker
+	}
+	if _, ok := w.(io.ReaderFrom); ok {
+		id += readerFrom
+	}
+	if _, ok := w.(http.Pusher); ok {
+		id += pusher
+	}
+
+	return pickDelegator[id](d)
+}

prometheus/promhttp/delegator_1_8.go

@@ -1,183 +0,0 @@
-// 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.
-
-// +build go1.8
-
-package promhttp
-
-import (
-	"io"
-	"net/http"
-)
-
-type pusherDelegator struct{ *responseWriterDelegator }
-
-func (d pusherDelegator) Push(target string, opts *http.PushOptions) error {
-	return d.ResponseWriter.(http.Pusher).Push(target, opts)
-}
-
-func init() {
-	pickDelegator[pusher] = func(d *responseWriterDelegator) delegator { // 16
-		return pusherDelegator{d}
-	}
-	pickDelegator[pusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 17
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+flusher] = func(d *responseWriterDelegator) delegator { // 18
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.Flusher
-		}{d, pusherDelegator{d}, flusherDelegator{d}}
-	}
-	pickDelegator[pusher+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 19
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.Flusher
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+hijacker] = func(d *responseWriterDelegator) delegator { // 20
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.Hijacker
-		}{d, pusherDelegator{d}, hijackerDelegator{d}}
-	}
-	pickDelegator[pusher+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 21
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.Hijacker
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 22
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.Hijacker
-			http.Flusher
-		}{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
-	}
-	pickDelegator[pusher+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { //23
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			http.Hijacker
-			http.Flusher
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom] = func(d *responseWriterDelegator) delegator { // 24
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-		}{d, pusherDelegator{d}, readerFromDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 25
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 26
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.Flusher
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, flusherDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 27
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.Flusher
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 28
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.Hijacker
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 29
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.Hijacker
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 30
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.Hijacker
-			http.Flusher
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
-	}
-	pickDelegator[pusher+readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 31
-		return struct {
-			*responseWriterDelegator
-			http.Pusher
-			io.ReaderFrom
-			http.Hijacker
-			http.Flusher
-			http.CloseNotifier
-		}{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}}
-	}
-}
-
-func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator {
-	d := &responseWriterDelegator{
-		ResponseWriter:     w,
-		observeWriteHeader: observeWriteHeaderFunc,
-	}
-
-	id := 0
-	//lint:ignore SA1019 http.CloseNotifier is deprecated but we don't want to
-	//remove support from client_golang yet.
-	if _, ok := w.(http.CloseNotifier); ok {
-		id += closeNotifier
-	}
-	if _, ok := w.(http.Flusher); ok {
-		id += flusher
-	}
-	if _, ok := w.(http.Hijacker); ok {
-		id += hijacker
-	}
-	if _, ok := w.(io.ReaderFrom); ok {
-		id += readerFrom
-	}
-	if _, ok := w.(http.Pusher); ok {
-		id += pusher
-	}
-
-	return pickDelegator[id](d)
-}

prometheus/promhttp/delegator_pre_1_8.go

@@ -1,44 +0,0 @@
-// 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.
-
-// +build !go1.8
-
-package promhttp
-
-import (
-	"io"
-	"net/http"
-)
-
-func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator {
-	d := &responseWriterDelegator{
-		ResponseWriter:     w,
-		observeWriteHeader: observeWriteHeaderFunc,
-	}
-
-	id := 0
-	if _, ok := w.(http.CloseNotifier); ok {
-		id += closeNotifier
-	}
-	if _, ok := w.(http.Flusher); ok {
-		id += flusher
-	}
-	if _, ok := w.(http.Hijacker); ok {
-		id += hijacker
-	}
-	if _, ok := w.(io.ReaderFrom); ok {
-		id += readerFrom
-	}
-
-	return pickDelegator[id](d)
-}

prometheus/promhttp/instrument_client.go

@@ -14,7 +14,10 @@
 package promhttp
 
 import (
+	"context"
+	"crypto/tls"
 	"net/http"
+	"net/http/httptrace"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -95,3 +98,123 @@ func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundT
 		return resp, err
 	})
 }
+
+// InstrumentTrace is used to offer flexibility in instrumenting the available
+// httptrace.ClientTrace hook functions. Each function is passed a float64
+// representing the time in seconds since the start of the http request. A user
+// may choose to use separately buckets Histograms, or implement custom
+// instance labels on a per function basis.
+type InstrumentTrace struct {
+	GotConn              func(float64)
+	PutIdleConn          func(float64)
+	GotFirstResponseByte func(float64)
+	Got100Continue       func(float64)
+	DNSStart             func(float64)
+	DNSDone              func(float64)
+	ConnectStart         func(float64)
+	ConnectDone          func(float64)
+	TLSHandshakeStart    func(float64)
+	TLSHandshakeDone     func(float64)
+	WroteHeaders         func(float64)
+	Wait100Continue      func(float64)
+	WroteRequest         func(float64)
+}
+
+// InstrumentRoundTripperTrace is a middleware that wraps the provided
+// RoundTripper and reports times to hook functions provided in the
+// InstrumentTrace struct. Hook functions that are not present in the provided
+// InstrumentTrace struct are ignored. Times reported to the hook functions are
+// time since the start of the request. Only with Go1.9+, those times are
+// guaranteed to never be negative. (Earlier Go versions are not using a
+// monotonic clock.) Note that partitioning of Histograms is expensive and
+// should be used judiciously.
+//
+// For hook functions that receive an error as an argument, no observations are
+// made in the event of a non-nil error value.
+//
+// See the example for ExampleInstrumentRoundTripperDuration for example usage.
+func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) RoundTripperFunc {
+	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		start := time.Now()
+
+		trace := &httptrace.ClientTrace{
+			GotConn: func(_ httptrace.GotConnInfo) {
+				if it.GotConn != nil {
+					it.GotConn(time.Since(start).Seconds())
+				}
+			},
+			PutIdleConn: func(err error) {
+				if err != nil {
+					return
+				}
+				if it.PutIdleConn != nil {
+					it.PutIdleConn(time.Since(start).Seconds())
+				}
+			},
+			DNSStart: func(_ httptrace.DNSStartInfo) {
+				if it.DNSStart != nil {
+					it.DNSStart(time.Since(start).Seconds())
+				}
+			},
+			DNSDone: func(_ httptrace.DNSDoneInfo) {
+				if it.DNSDone != nil {
+					it.DNSDone(time.Since(start).Seconds())
+				}
+			},
+			ConnectStart: func(_, _ string) {
+				if it.ConnectStart != nil {
+					it.ConnectStart(time.Since(start).Seconds())
+				}
+			},
+			ConnectDone: func(_, _ string, err error) {
+				if err != nil {
+					return
+				}
+				if it.ConnectDone != nil {
+					it.ConnectDone(time.Since(start).Seconds())
+				}
+			},
+			GotFirstResponseByte: func() {
+				if it.GotFirstResponseByte != nil {
+					it.GotFirstResponseByte(time.Since(start).Seconds())
+				}
+			},
+			Got100Continue: func() {
+				if it.Got100Continue != nil {
+					it.Got100Continue(time.Since(start).Seconds())
+				}
+			},
+			TLSHandshakeStart: func() {
+				if it.TLSHandshakeStart != nil {
+					it.TLSHandshakeStart(time.Since(start).Seconds())
+				}
+			},
+			TLSHandshakeDone: func(_ tls.ConnectionState, err error) {
+				if err != nil {
+					return
+				}
+				if it.TLSHandshakeDone != nil {
+					it.TLSHandshakeDone(time.Since(start).Seconds())
+				}
+			},
+			WroteHeaders: func() {
+				if it.WroteHeaders != nil {
+					it.WroteHeaders(time.Since(start).Seconds())
+				}
+			},
+			Wait100Continue: func() {
+				if it.Wait100Continue != nil {
+					it.Wait100Continue(time.Since(start).Seconds())
+				}
+			},
+			WroteRequest: func(_ httptrace.WroteRequestInfo) {
+				if it.WroteRequest != nil {
+					it.WroteRequest(time.Since(start).Seconds())
+				}
+			},
+		}
+		r = r.WithContext(httptrace.WithClientTrace(context.Background(), trace))
+
+		return next.RoundTrip(r)
+	})
+}

prometheus/promhttp/instrument_client_1_8.go

@@ -1,144 +0,0 @@
-// 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.
-
-// +build go1.8
-
-package promhttp
-
-import (
-	"context"
-	"crypto/tls"
-	"net/http"
-	"net/http/httptrace"
-	"time"
-)
-
-// InstrumentTrace is used to offer flexibility in instrumenting the available
-// httptrace.ClientTrace hook functions. Each function is passed a float64
-// representing the time in seconds since the start of the http request. A user
-// may choose to use separately buckets Histograms, or implement custom
-// instance labels on a per function basis.
-type InstrumentTrace struct {
-	GotConn              func(float64)
-	PutIdleConn          func(float64)
-	GotFirstResponseByte func(float64)
-	Got100Continue       func(float64)
-	DNSStart             func(float64)
-	DNSDone              func(float64)
-	ConnectStart         func(float64)
-	ConnectDone          func(float64)
-	TLSHandshakeStart    func(float64)
-	TLSHandshakeDone     func(float64)
-	WroteHeaders         func(float64)
-	Wait100Continue      func(float64)
-	WroteRequest         func(float64)
-}
-
-// InstrumentRoundTripperTrace is a middleware that wraps the provided
-// RoundTripper and reports times to hook functions provided in the
-// InstrumentTrace struct. Hook functions that are not present in the provided
-// InstrumentTrace struct are ignored. Times reported to the hook functions are
-// time since the start of the request. Only with Go1.9+, those times are
-// guaranteed to never be negative. (Earlier Go versions are not using a
-// monotonic clock.) Note that partitioning of Histograms is expensive and
-// should be used judiciously.
-//
-// For hook functions that receive an error as an argument, no observations are
-// made in the event of a non-nil error value.
-//
-// See the example for ExampleInstrumentRoundTripperDuration for example usage.
-func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) RoundTripperFunc {
-	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
-		start := time.Now()
-
-		trace := &httptrace.ClientTrace{
-			GotConn: func(_ httptrace.GotConnInfo) {
-				if it.GotConn != nil {
-					it.GotConn(time.Since(start).Seconds())
-				}
-			},
-			PutIdleConn: func(err error) {
-				if err != nil {
-					return
-				}
-				if it.PutIdleConn != nil {
-					it.PutIdleConn(time.Since(start).Seconds())
-				}
-			},
-			DNSStart: func(_ httptrace.DNSStartInfo) {
-				if it.DNSStart != nil {
-					it.DNSStart(time.Since(start).Seconds())
-				}
-			},
-			DNSDone: func(_ httptrace.DNSDoneInfo) {
-				if it.DNSDone != nil {
-					it.DNSDone(time.Since(start).Seconds())
-				}
-			},
-			ConnectStart: func(_, _ string) {
-				if it.ConnectStart != nil {
-					it.ConnectStart(time.Since(start).Seconds())
-				}
-			},
-			ConnectDone: func(_, _ string, err error) {
-				if err != nil {
-					return
-				}
-				if it.ConnectDone != nil {
-					it.ConnectDone(time.Since(start).Seconds())
-				}
-			},
-			GotFirstResponseByte: func() {
-				if it.GotFirstResponseByte != nil {
-					it.GotFirstResponseByte(time.Since(start).Seconds())
-				}
-			},
-			Got100Continue: func() {
-				if it.Got100Continue != nil {
-					it.Got100Continue(time.Since(start).Seconds())
-				}
-			},
-			TLSHandshakeStart: func() {
-				if it.TLSHandshakeStart != nil {
-					it.TLSHandshakeStart(time.Since(start).Seconds())
-				}
-			},
-			TLSHandshakeDone: func(_ tls.ConnectionState, err error) {
-				if err != nil {
-					return
-				}
-				if it.TLSHandshakeDone != nil {
-					it.TLSHandshakeDone(time.Since(start).Seconds())
-				}
-			},
-			WroteHeaders: func() {
-				if it.WroteHeaders != nil {
-					it.WroteHeaders(time.Since(start).Seconds())
-				}
-			},
-			Wait100Continue: func() {
-				if it.Wait100Continue != nil {
-					it.Wait100Continue(time.Since(start).Seconds())
-				}
-			},
-			WroteRequest: func(_ httptrace.WroteRequestInfo) {
-				if it.WroteRequest != nil {
-					it.WroteRequest(time.Since(start).Seconds())
-				}
-			},
-		}
-		r = r.WithContext(httptrace.WithClientTrace(context.Background(), trace))
-
-		return next.RoundTrip(r)
-	})
-}