Merge pull request #20387 from ahrtr/20250722_learner_3.6

[release-3.6] Check promotion against v2store when updating v2store

Author: ahrtr

server/etcdserver/api/membership/cluster.go

@@ -522,8 +522,9 @@ func (c *RaftCluster) PromoteMember(id types.ID, shouldApplyV3 ShouldApplyV3) {
 	defer c.Unlock()
 
 	if c.v2store != nil {
-		if _, ok := c.members[id]; ok {
-			m := *(c.members[id])
+		membersMap, _ := membersFromStore(c.lg, c.v2store)
+		if _, ok := membersMap[id]; ok {
+			m := *(membersMap[id])
 			m.RaftAttributes.IsLearner = false
 			mustUpdateMemberInStore(c.lg, c.v2store, &m)
 		} else {

tests/e2e/member_no_proxy_test.go

@@ -0,0 +1,63 @@
+// Copyright 2025 The etcd 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 !cluster_proxy
+
+package e2e
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"go.etcd.io/etcd/tests/v3/framework/e2e"
+	"go.etcd.io/etcd/tests/v3/framework/testutils"
+)
+
+// TestReproduce20340 reproduces the issue https://github.com/etcd-io/etcd/issues/20340.
+// Refer to https://github.com/etcd-io/etcd/issues/20340#issuecomment-3105037914.
+func TestReproduce20340(t *testing.T) {
+	e2e.BeforeTest(t)
+
+	ctx := context.Background()
+
+	epc, members := mustCreateNewClusterByPromotingMembers(t, e2e.CurrentVersion, 3)
+	defer func() {
+		require.NoError(t, epc.Close())
+	}()
+
+	t.Logf("Removing the second member (%x)", members[0].ID)
+	etcdctl := epc.Procs[0].Etcdctl()
+	testutils.ExecuteWithTimeout(t, 10*time.Second, func() {
+		for {
+			_, merr := etcdctl.MemberRemove(ctx, members[0].ID)
+			if merr != nil {
+				if strings.Contains(merr.Error(), "etcdserver: unhealthy cluster") {
+					time.Sleep(1 * time.Second)
+					continue
+				}
+				t.Fatalf("failed to remove member: %s", merr.Error())
+			}
+			break
+		}
+	})
+
+	epc.Procs = append(epc.Procs[:1], epc.Procs[2:]...)
+
+	t.Logf("Restarting member: %s", epc.Procs[0].Config().Name)
+	require.NoError(t, epc.Procs[0].Restart(ctx))
+}