Merge pull request #561 from prometheus/beorn7/go-requirement

Increase minimum required Go version to 1.9

.travis.yml

@@ -1,15 +1,13 @@
 language: go
 
 go:
-  - 1.7.x # See README.md for current minimum version.
-  - 1.8.x
-  - 1.9.x
+  - 1.9.x # See README.md for current minimum version.
   - 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
-  # style is only checked against the latest supported Go version.
+  - if [[ ! $TRAVIS_GO_VERSION =~ ^1\.9\.[x0-9]+$ ]]; then make lint; fi
+  # 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)
+}