etcdserver: recover cluster version from backend

clientv3/integration/kv_test.go

@@ -893,7 +893,7 @@ func TestKVLargeRequests(t *testing.T) {
 		expectError error
 	}{
 		{
-			maxRequestBytesServer:  1,
+			maxRequestBytesServer:  256,
 			maxCallSendBytesClient: 0,
 			maxCallRecvBytesClient: 0,
 			valueSize:              1024,

etcdserver/api/membership/cluster.go

@@ -247,7 +247,7 @@ func (c *RaftCluster) Recover(onSet func(*zap.Logger, *semver.Version)) {
 	defer c.Unlock()
 
 	c.members, c.removed = membersFromStore(c.lg, c.v2store)
-	c.version = clusterVersionFromStore(c.lg, c.v2store)
+	c.version = clusterVersionFromBackend(c.lg, c.be)
 	mustDetectDowngrade(c.lg, c.version)
 	onSet(c.lg, c.version)
 
@@ -753,6 +753,26 @@ func clusterVersionFromStore(lg *zap.Logger, st v2store.Store) *semver.Version {
 	return semver.Must(semver.NewVersion(*e.Node.Value))
 }
 
+func clusterVersionFromBackend(lg *zap.Logger, be backend.Backend) *semver.Version {
+	ckey := backendClusterVersionKey()
+	tx := be.ReadTx()
+	tx.RLock()
+	defer tx.RUnlock()
+	keys, vals := tx.UnsafeRange(clusterBucketName, ckey, nil, 0)
+	if len(keys) == 0 {
+		return nil
+	}
+	if len(keys) != 1 {
+		if lg != nil {
+			lg.Panic(
+				"unexpected number of keys when getting cluster version from backend",
+				zap.Int("number fo keys", len(keys)),
+			)
+		}
+	}
+	return semver.Must(semver.NewVersion(string(vals[0])))
+}
+
 // ValidateClusterAndAssignIDs validates the local cluster by matching the PeerURLs
 // with the existing cluster. If the validation succeeds, it assigns the IDs
 // from the existing cluster to the local cluster.

integration/v3_grpc_test.go

@@ -1898,7 +1898,7 @@ func TestV3LargeRequests(t *testing.T) {
 		expectError     error
 	}{
 		// don't set to 0. use 0 as the default.
-		{1, 1024, rpctypes.ErrGRPCRequestTooLarge},
+		{256, 1024, rpctypes.ErrGRPCRequestTooLarge},
 		{10 * 1024 * 1024, 9 * 1024 * 1024, nil},
 		{10 * 1024 * 1024, 10 * 1024 * 1024, rpctypes.ErrGRPCRequestTooLarge},
 		{10 * 1024 * 1024, 10*1024*1024 + 5, rpctypes.ErrGRPCRequestTooLarge},