From bade01efec6bd14b557554060d1e9065227c537b Mon Sep 17 00:00:00 2001
From: Marek Siarkowicz <siarkowicz@google.com>
Date: Wed, 6 Oct 2021 15:10:30 +0200
Subject: [PATCH] server: Use server version to decide if to downgrade has
 finished

---
 server/etcdserver/version/monitor.go      |  4 +++-
 server/etcdserver/version/monitor_test.go | 20 +++++++++++++++++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/server/etcdserver/version/monitor.go b/server/etcdserver/version/monitor.go
index d3c0a1e4945c..be19e8e9e447 100644
--- a/server/etcdserver/version/monitor.go
+++ b/server/etcdserver/version/monitor.go
@@ -178,11 +178,12 @@ func (m *Monitor) membersMinimalVersion() *semver.Version {
 // It can be used to decide the whether the cluster finishes downgrading to target version.
 func (m *Monitor) versionsMatchTarget(targetVersion *semver.Version) bool {
 	vers := m.s.GetMembersVersions()
+	targetVersion = &semver.Version{Major: targetVersion.Major, Minor: targetVersion.Minor}
 	for mid, ver := range vers {
 		if ver == nil {
 			return false
 		}
-		v, err := semver.NewVersion(ver.Cluster)
+		v, err := semver.NewVersion(ver.Server)
 		if err != nil {
 			m.lg.Warn(
 				"failed to parse server version of remote member",
@@ -192,6 +193,7 @@ func (m *Monitor) versionsMatchTarget(targetVersion *semver.Version) bool {
 			)
 			return false
 		}
+		v = &semver.Version{Major: v.Major, Minor: v.Minor}
 		if !targetVersion.Equal(*v) {
 			m.lg.Warn("remotes server has mismatching etcd version",
 				zap.String("remote-member-id", mid),
diff --git a/server/etcdserver/version/monitor_test.go b/server/etcdserver/version/monitor_test.go
index 342f3e9a9cff..2cefd32b0a18 100644
--- a/server/etcdserver/version/monitor_test.go
+++ b/server/etcdserver/version/monitor_test.go
@@ -127,7 +127,7 @@ func TestVersionMatchTarget(t *testing.T) {
 			"When cannot parse peer version",
 			&semver.Version{Major: 3, Minor: 4},
 			map[string]*version.Versions{
-				"mem1": {Server: "3.4.1", Cluster: "3.4"},
+				"mem1": {Server: "3.4", Cluster: "3.4.0"},
 				"mem2": {Server: "3.4.2-pre", Cluster: "3.4.0"},
 				"mem3": {Server: "3.4.2", Cluster: "3.4.0"},
 			},
@@ -277,6 +277,24 @@ func TestCancelDowngradeIfNeeded(t *testing.T) {
 				"b": {Cluster: "3.6.0", Server: "3.6.2"},
 			},
 		},
+		{
+			name: "Continue downgrade if just started",
+			memberVersions: map[string]*version.Versions{
+				"a": {Cluster: "3.5.0", Server: "3.6.1"},
+				"b": {Cluster: "3.5.0", Server: "3.6.2"},
+			},
+			downgrade:       &DowngradeInfo{TargetVersion: "3.5.0", Enabled: true},
+			expectDowngrade: &DowngradeInfo{TargetVersion: "3.5.0", Enabled: true},
+		},
+		{
+			name: "Continue downgrade if there is at least one member with not matching",
+			memberVersions: map[string]*version.Versions{
+				"a": {Cluster: "3.5.0", Server: "3.5.1"},
+				"b": {Cluster: "3.5.0", Server: "3.6.2"},
+			},
+			downgrade:       &DowngradeInfo{TargetVersion: "3.5.0", Enabled: true},
+			expectDowngrade: &DowngradeInfo{TargetVersion: "3.5.0", Enabled: true},
+		},
 		{
 			name: "Cancel downgrade if all members have downgraded",
 			memberVersions: map[string]*version.Versions{