server: Integrate version validation logic into tests

server/etcdserver/api/membership/cluster.go

@@ -273,7 +273,8 @@ func (c *RaftCluster) Recover(onSet func(*zap.Logger, *semver.Version)) {
 	if c.downgradeInfo != nil {
 		d = &serverversion.DowngradeInfo{Enabled: c.downgradeInfo.Enabled, TargetVersion: c.downgradeInfo.TargetVersion}
 	}
-	serverversion.MustDetectDowngrade(c.lg, c.version, d)
+	sv := semver.Must(semver.NewVersion(version.Version))
+	serverversion.MustDetectDowngrade(c.lg, sv, c.version, d)
 	onSet(c.lg, c.version)
 
 	for _, m := range c.members {
@@ -541,7 +542,8 @@ func (c *RaftCluster) SetVersion(ver *semver.Version, onSet func(*zap.Logger, *s
 	}
 	oldVer := c.version
 	c.version = ver
-	serverversion.MustDetectDowngrade(c.lg, c.version, c.downgradeInfo)
+	sv := semver.Must(semver.NewVersion(version.Version))
+	serverversion.MustDetectDowngrade(c.lg, sv, c.version, c.downgradeInfo)
 	if c.v2store != nil {
 		mustSaveClusterVersionToStore(c.lg, c.v2store, ver)
 	}

server/etcdserver/version/downgrade.go

@@ -34,47 +34,46 @@ func (d *DowngradeInfo) GetTargetVersion() *semver.Version {
 
 // isValidDowngrade verifies whether the cluster can be downgraded from verFrom to verTo
 func isValidDowngrade(verFrom *semver.Version, verTo *semver.Version) bool {
-	return verTo.Equal(*AllowedDowngradeVersion(verFrom))
+	return verTo.Equal(*allowedDowngradeVersion(verFrom))
 }
 
 // MustDetectDowngrade will detect unexpected downgrade when the local server is recovered.
-func MustDetectDowngrade(lg *zap.Logger, cv *semver.Version, d *DowngradeInfo) {
-	lv := semver.Must(semver.NewVersion(version.Version))
+func MustDetectDowngrade(lg *zap.Logger, sv, cv *semver.Version, d *DowngradeInfo) {
 	// only keep major.minor version for comparison against cluster version
-	lv = &semver.Version{Major: lv.Major, Minor: lv.Minor}
+	sv = &semver.Version{Major: sv.Major, Minor: sv.Minor}
 
 	// if the cluster enables downgrade, check local version against downgrade target version.
 	if d != nil && d.Enabled && d.TargetVersion != "" {
-		if lv.Equal(*d.GetTargetVersion()) {
+		if sv.Equal(*d.GetTargetVersion()) {
 			if cv != nil {
 				lg.Info(
 					"cluster is downgrading to target version",
 					zap.String("target-cluster-version", d.TargetVersion),
 					zap.String("determined-cluster-version", version.Cluster(cv.String())),
-					zap.String("current-server-version", version.Version),
+					zap.String("current-server-version", sv.String()),
 				)
 			}
 			return
 		}
 		lg.Panic(
 			"invalid downgrade; server version is not allowed to join when downgrade is enabled",
-			zap.String("current-server-version", version.Version),
+			zap.String("current-server-version", sv.String()),
 			zap.String("target-cluster-version", d.TargetVersion),
 		)
 	}
 
 	// if the cluster disables downgrade, check local version against determined cluster version.
 	// the validation passes when local version is not less than cluster version
-	if cv != nil && lv.LessThan(*cv) {
+	if cv != nil && sv.LessThan(*cv) {
 		lg.Panic(
 			"invalid downgrade; server version is lower than determined cluster version",
-			zap.String("current-server-version", version.Version),
+			zap.String("current-server-version", sv.String()),
 			zap.String("determined-cluster-version", version.Cluster(cv.String())),
 		)
 	}
 }
 
-func AllowedDowngradeVersion(ver *semver.Version) *semver.Version {
+func allowedDowngradeVersion(ver *semver.Version) *semver.Version {
 	// Todo: handle the case that downgrading from higher major version(e.g. downgrade from v4.0 to v3.x)
 	return &semver.Version{Major: ver.Major, Minor: ver.Minor - 1}
 }

server/etcdserver/version/downgrade_test.go

@@ -110,7 +110,8 @@ func TestMustDetectDowngrade(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			lg := zaptest.NewLogger(t)
-			err := tryMustDetectDowngrade(lg, tt.clusterVersion, tt.downgrade)
+			sv := semver.Must(semver.NewVersion(version.Version))
+			err := tryMustDetectDowngrade(lg, sv, tt.clusterVersion, tt.downgrade)
 
 			if tt.success != (err == nil) {
 				t.Errorf("Unexpected status, got %q, wanted: %v", err, tt.success)
@@ -123,11 +124,11 @@ func TestMustDetectDowngrade(t *testing.T) {
 	}
 }
 
-func tryMustDetectDowngrade(lg *zap.Logger, cv *semver.Version, d *DowngradeInfo) (err interface{}) {
+func tryMustDetectDowngrade(lg *zap.Logger, sv, cv *semver.Version, d *DowngradeInfo) (err interface{}) {
 	defer func() {
 		err = recover()
 	}()
-	MustDetectDowngrade(lg, cv, d)
+	MustDetectDowngrade(lg, sv, cv, d)
 	return err
 }
 

server/etcdserver/version/version.go

@@ -44,7 +44,7 @@ func (m *Manager) DowngradeValidate(ctx context.Context, targetVersion *semver.V
 		return err
 	}
 	cv := m.s.GetClusterVersion()
-	allowedTargetVersion := AllowedDowngradeVersion(cv)
+	allowedTargetVersion := allowedDowngradeVersion(cv)
 	if !targetVersion.Equal(*allowedTargetVersion) {
 		return ErrInvalidDowngradeTargetVersion
 	}

server/etcdserver/version/version_test.go

@@ -64,6 +64,7 @@ func TestUpgradeThreeNodes(t *testing.T) {
 
 func newCluster(lg *zap.Logger, memberCount int, ver semver.Version) *clusterMock {
 	cluster := &clusterMock{
+		lg:             lg,
 		clusterVersion: ver,
 		members:        make([]*memberMock, 0, memberCount),
 	}
@@ -99,13 +100,14 @@ func (c *clusterMock) StepMonitors() {
 }
 
 type clusterMock struct {
+	lg             *zap.Logger
 	clusterVersion semver.Version
 	downgradeInfo  *DowngradeInfo
 	members        []*memberMock
 }
 
-func (c *clusterMock) DowngradeEnable(ver semver.Version) {
-	c.downgradeInfo = &DowngradeInfo{TargetVersion: ver.String(), Enabled: true}
+func (c *clusterMock) Version() *Manager {
+	return NewManager(c.lg, c.members[0])
 }
 
 func (c *clusterMock) MembersVersions() map[string]*version.Versions {
@@ -120,9 +122,7 @@ func (c *clusterMock) MembersVersions() map[string]*version.Versions {
 }
 
 func (c *clusterMock) ReplaceMemberBinary(mid int, newServerVersion semver.Version) {
-	if newServerVersion.LessThan(c.clusterVersion) {
-		panic("Members cannot join clusters with higher version")
-	}
+	MustDetectDowngrade(c.lg, &c.members[mid].serverVersion, &c.clusterVersion, c.downgradeInfo)
 	c.members[mid].serverVersion = newServerVersion
 }
 
@@ -146,7 +146,10 @@ func (m *memberMock) LinearizableReadNotify(ctx context.Context) error {
 }
 
 func (m *memberMock) DowngradeEnable(ctx context.Context, targetVersion *semver.Version) error {
-	m.cluster.downgradeInfo = nil
+	m.cluster.downgradeInfo = &DowngradeInfo{
+		TargetVersion: targetVersion.String(),
+		Enabled:       true,
+	}
 	return nil
 }