Add new Go collector example

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

.gitignore

@@ -1,6 +1,7 @@
 # Examples
 examples/simple/simple
 examples/random/random
+examples/gocollector/gocollector
 
 # Typical backup/temporary files of editors
 *~

Dockerfile

@@ -21,11 +21,14 @@ WORKDIR /go/src/github.com/prometheus/client_golang/examples/random
 RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
 WORKDIR /go/src/github.com/prometheus/client_golang/examples/simple
 RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
+WORKDIR /go/src/github.com/prometheus/client_golang/examples/gocollector
+RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
 
 # Final image.
 FROM quay.io/prometheus/busybox:latest
 LABEL maintainer="The Prometheus Authors <prometheus-developers@googlegroups.com>"
 COPY --from=builder /go/src/github.com/prometheus/client_golang/examples/random \
-    /go/src/github.com/prometheus/client_golang/examples/simple ./
+    /go/src/github.com/prometheus/client_golang/examples/simple \
+    /go/src/github.com/prometheus/client_golang/examples/gocollector ./
 EXPOSE 8080
-CMD ["echo", "Please run an example. Either /random or /simple"]
+CMD ["echo", "Please run an example. Either /random, /simple or /gocollector"]

examples/gocollector/main.go

@@ -0,0 +1,55 @@
+// Copyright 2022 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.
+
+//go:build go1.17
+// +build go1.17
+
+// A minimal example of how to include Prometheus instrumentation.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var addr = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
+
+func main() {
+	flag.Parse()
+
+	// Create a new registry.
+	reg := prometheus.NewRegistry()
+
+	// Add Go module build info.
+	reg.MustRegister(collectors.NewBuildInfoCollector())
+	reg.MustRegister(collectors.NewGoCollector(
+		collectors.WithGoCollections(collectors.GoRuntimeMemStatsCollection | collectors.GoRuntimeMetricsCollection),
+	))
+
+	// Expose the registered metrics via HTTP.
+	http.Handle("/metrics", promhttp.HandlerFor(
+		reg,
+		promhttp.HandlerOpts{
+			// Opt into OpenMetrics to support exemplars.
+			EnableOpenMetrics: true,
+		},
+	))
+	fmt.Println("Hello world from new Go Collector!")
+	log.Fatal(http.ListenAndServe(*addr, nil))
+}

prometheus/collectors/go_collector_latest.go

@@ -72,9 +72,9 @@ const (
 //
 // The current default is GoRuntimeMemStatsCollection, so the compatibility mode with
 // client_golang pre v1.12 (move to runtime/metrics).
-func WithGoCollections(flags uint32) goOption {
+func WithGoCollections(flags GoCollectionOption) goOption {
 	return func(o *goOptions) {
-		o.EnabledCollections = flags
+		o.EnabledCollections = uint32(flags)
 	}
 }