br/pdutils: retry when encountered dns error (#53005) (#53032)

close #53029

br/pkg/lightning/common/retry.go

@@ -108,6 +108,10 @@ func isSingleRetryableError(err error) bool {
 
 	switch nerr := err.(type) {
 	case net.Error:
+		var dErr *net.DNSError
+		if goerrors.As(nerr, &dErr) {
+			return true
+		}
 		if nerr.Timeout() {
 			return true
 		}

br/pkg/lightning/common/retry_test.go

@@ -38,7 +38,7 @@ func TestIsRetryableError(t *testing.T) {
 	require.True(t, IsRetryableError(ErrWriteTooSlow))
 	require.False(t, IsRetryableError(io.EOF))
 	require.False(t, IsRetryableError(&net.AddrError{}))
-	require.False(t, IsRetryableError(&net.DNSError{}))
+	require.True(t, IsRetryableError(&net.DNSError{}))
 	require.True(t, IsRetryableError(&net.DNSError{IsTimeout: true}))
 
 	// kv errors

br/pkg/pdutil/pd.go

@@ -53,6 +53,7 @@ const (
 
 	// pd request retry time when connection fail
 	pdRequestRetryTime = 120
+
 	// set max-pending-peer-count to a large value to avoid scatter region failed.
 	maxPendingPeerUnlimited uint64 = math.MaxInt32
 )
@@ -177,6 +178,10 @@ func pdRequestWithCode(
 		if err != nil {
 			return 0, nil, errors.Trace(err)
 		}
+		failpoint.Inject("DNSError", func() {
+			req.Host = "nosuchhost"
+			req.URL.Host = "nosuchhost"
+		})
 		resp, err = cli.Do(req) //nolint:bodyclose
 		count++
 		failpoint.Inject("InjectClosed", func(v failpoint.Value) {

tests/realtikvtest/brietest/BUILD.bazel

@@ -9,10 +9,12 @@ go_test(
         "brie_test.go",
         "main_test.go",
         "operator_test.go",
+        "pdutil_test.go",
     ],
     flaky = True,
     race = "on",
     deps = [
+        "//br/pkg/pdutil",
         "//br/pkg/task",
         "//br/pkg/task/operator",
         "//pkg/config",

tests/realtikvtest/brietest/pdutil_test.go

@@ -0,0 +1,33 @@
+// Copyright 2024 PingCAP, Inc.
+//
+// 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.
+
+package brietest
+
+import (
+	"context"
+	"testing"
+
+	"github.com/pingcap/failpoint"
+	"github.com/pingcap/tidb/br/pkg/pdutil"
+	"github.com/stretchr/testify/require"
+	pd "github.com/tikv/pd/client"
+)
+
+func TestCreateClient(t *testing.T) {
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/br/pkg/pdutil/DNSError", "119*return"))
+	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/br/pkg/pdutil/FastRetry", "return(true)"))
+	ctl, err := pdutil.NewPdController(context.Background(), "127.0.0.1:2379", nil, pd.SecurityOption{})
+	require.NoError(t, err)
+	ctl.Close()
+}