prevent ping from forwarding

Signed-off-by: Ryan Leung <rleungx@gmail.com>

server/cluster/cluster.go

@@ -65,6 +65,7 @@ import (
 	"github.com/tikv/pd/pkg/syncer"
 	"github.com/tikv/pd/pkg/tso"
 	"github.com/tikv/pd/pkg/unsaferecovery"
+	"github.com/tikv/pd/pkg/utils/apiutil"
 	"github.com/tikv/pd/pkg/utils/etcdutil"
 	"github.com/tikv/pd/pkg/utils/keypath"
 	"github.com/tikv/pd/pkg/utils/logutil"
@@ -2504,6 +2505,7 @@ func CheckHealth(client *http.Client, members []*pdpb.Member) map[uint64]*pdpb.M
 		for _, cURL := range member.ClientUrls {
 			ctx, cancel := context.WithTimeout(context.Background(), clientTimeout)
 			req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("%s%s", cURL, healthURL), http.NoBody)
+			req.Header.Set(apiutil.PDAllowFollowerHandleHeader, "true")
 			if err != nil {
 				log.Error("failed to new request", errs.ZapError(errs.ErrNewHTTPRequest, err))
 				cancel()

tests/server/api/api_test.go

@@ -672,6 +672,41 @@ func (suite *redirectorTestSuite) TestAllowFollowerHandle() {
 	re.NoError(err)
 }
 
+func (suite *redirectorTestSuite) TestPing() {
+	re := suite.Require()
+	// Find a follower.
+	var follower *server.Server
+	leader := suite.cluster.GetLeaderServer()
+	for _, svr := range suite.cluster.GetServers() {
+		if svr != leader {
+			follower = svr.GetServer()
+			break
+		}
+	}
+
+	for _, svr := range suite.cluster.GetServers() {
+		if svr.GetServer() != follower {
+			svr.Stop()
+		}
+	}
+	addr := follower.GetAddr() + "/pd/api/v1/ping"
+	request, err := http.NewRequest(http.MethodGet, addr, http.NoBody)
+	// ping request should not be redirected.
+	request.Header.Add(apiutil.PDAllowFollowerHandleHeader, "true")
+	re.NoError(err)
+	resp, err := tests.TestDialClient.Do(request)
+	re.NoError(err)
+	defer resp.Body.Close()
+	re.Equal(http.StatusOK, resp.StatusCode)
+	_, err = io.ReadAll(resp.Body)
+	re.NoError(err)
+	for _, svr := range suite.cluster.GetServers() {
+		if svr.GetServer() != follower {
+			svr.Run()
+		}
+	}
+}
+
 func (suite *redirectorTestSuite) TestNotLeader() {
 	re := suite.Require()
 	// Find a follower.

tools/pd-ctl/pdctl/command/ping_command.go

@@ -19,6 +19,8 @@ import (
 	"time"
 
 	"github.com/spf13/cobra"
+
+	"github.com/tikv/pd/pkg/utils/apiutil"
 )
 
 const pingPrefix = "pd/api/v1/ping"
@@ -35,7 +37,7 @@ func NewPingCommand() *cobra.Command {
 
 func showPingCommandFunc(cmd *cobra.Command, _ []string) {
 	start := time.Now()
-	_, err := doRequest(cmd, pingPrefix, http.MethodGet, http.Header{})
+	_, err := doRequest(cmd, pingPrefix, http.MethodGet, http.Header{apiutil.PDAllowFollowerHandleHeader: {"true"}}, nil)
 	if err != nil {
 		cmd.Println(err)
 		return