Remove HostnameGrouping method

prometheus/push/deprecated.go

@@ -164,8 +164,11 @@ func pushCollectors(job string, grouping map[string]string, url, method string,
 // returned map is created upon each call so that the caller is free to add more
 // labels to the map.
 //
-// Deprecated: It is recommended to use a Pusher created with New, which has a
+// Deprecated: Usually, metrics pushed to the Pushgateway should not be
-// method HostnameGrouping.
+// host-centric. (You would use https://github.com/prometheus/node_exporter in
+// that case.) If you have the need to add the hostname to the grouping key, you
+// are probably doing something wrong. See
+// https://prometheus.io/docs/practices/pushing/ for details.
 func HostnameGroupingKey() map[string]string {
 	hostname, err := os.Hostname()
 	if err != nil {

prometheus/push/examples_test.go

@@ -28,7 +28,7 @@ func ExamplePusher_Push() {
 	completionTime.SetToCurrentTime()
 	if err := push.New("http://pushgateway:9091", "db_backup").
 		Collector(completionTime).
-		HostnameGrouping().
+		Grouping("db", "customers").
 		Push(); err != nil {
 		fmt.Println("Could not push completion time to Pushgateway:", err)
 	}

prometheus/push/push.go

@@ -41,7 +41,6 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
-	"os"
 	"strings"
 
 	"github.com/prometheus/common/expfmt"
@@ -167,21 +166,6 @@ func (p *Pusher) Grouping(name, value string) *Pusher {
 	return p
 }
 
-// HostnameGrouping adds a label pair with “instance” as the name and the
-// current hostname as the value to the grouping key of the Pusher. If the
-// hostname cannot be determined, “unknown” is used as the label value. For
-// further implications of setting a grouping key, see the Grouping method.
-//
-// For convenience, this method returns a pointer to the Pusher itself.
-func (p *Pusher) HostnameGrouping() *Pusher {
-	hostname, err := os.Hostname()
-	if err != nil {
-		hostname = "unknown"
-	}
-	p.grouping["instance"] = hostname
-	return p
-}
-
 // Client sets a custom HTTP client for the Pusher. For convenience, this method
 // returns a pointer to the Pusher itself.
 func (p *Pusher) Client(c *http.Client) *Pusher {

prometheus/push/push_test.go

@@ -24,7 +24,6 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
-	"os"
 	"testing"
 
 	"github.com/prometheus/common/expfmt"
@@ -40,11 +39,6 @@ func TestPush(t *testing.T) {
 		lastPath   string
 	)
 
-	host, err := os.Hostname()
-	if err != nil {
-		t.Error(err)
-	}
-
 	// Fake a Pushgateway that always responds with 202.
 	pgwOK := httptest.NewServer(
 		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -100,7 +94,6 @@ func TestPush(t *testing.T) {
 
 	// Push some Collectors, all good.
 	if err := New(pgwOK.URL, "testjob").
-		HostnameGrouping().
 		Collector(metric1).
 		Collector(metric2).
 		Push(); err != nil {
@@ -112,7 +105,7 @@ func TestPush(t *testing.T) {
 	if bytes.Compare(lastBody, wantBody) != 0 {
 		t.Errorf("got body %v, want %v", lastBody, wantBody)
 	}
-	if lastPath != "/metrics/job/testjob/instance/"+host {
+	if lastPath != "/metrics/job/testjob" {
 		t.Error("unexpected path:", lastPath)
 	}
 
@@ -176,7 +169,6 @@ func TestPush(t *testing.T) {
 
 	// Push registry, all good.
 	if err := New(pgwOK.URL, "testjob").
-		HostnameGrouping().
 		Gatherer(reg).
 		Push(); err != nil {
 		t.Fatal(err)