*: LeaseTimeToLive returns error if leader changed

server/etcdserver/v3_server.go

@@ -357,6 +357,9 @@ func (s *EtcdServer) leaseTimeToLive(ctx context.Context, r *pb.LeaseTimeToLiveR
 		if err := s.waitAppliedIndex(); err != nil {
 			return nil, err
 		}
+
+		// gofail: var beforeLookupWhenLeaseTimeToLive struct{}
+
 		// primary; timetolive directly from leader
 		le := s.lessor.Lookup(lease.LeaseID(r.ID))
 		if le == nil {
@@ -372,6 +375,15 @@ func (s *EtcdServer) leaseTimeToLive(ctx context.Context, r *pb.LeaseTimeToLiveR
 			}
 			resp.Keys = kbs
 		}
+
+		// The leasor could be demoted if leader changed during lookup.
+		// We should return error to force retry instead of returning
+		// incorrect remaining TTL.
+		if le.Demoted() {
+			// NOTE: lease.ErrNotPrimary is not retryable error for
+			// client. Instead, uses ErrLeaderChanged.
+			return nil, errors.ErrLeaderChanged
+		}
 		return resp, nil
 	}
 

server/lease/lease.go

@@ -95,6 +95,13 @@ func (l *Lease) forever() {
 	l.expiry = forever
 }
 
+// Demoted returns true if the lease's expiry has been reset to forever.
+func (l *Lease) Demoted() bool {
+	l.expiryMu.Lock()
+	defer l.expiryMu.Unlock()
+	return l.expiry == forever
+}
+
 // Keys returns all the keys attached to the lease.
 func (l *Lease) Keys() []string {
 	l.mu.RLock()

server/lease/leasehttp/http.go

@@ -103,6 +103,9 @@ func (h *leaseHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, ErrLeaseHTTPTimeout.Error(), http.StatusRequestTimeout)
 			return
 		}
+
+		// gofail: var beforeLookupWhenForwardLeaseTimeToLive struct{}
+
 		l := h.l.Lookup(lease.LeaseID(lreq.LeaseTimeToLiveRequest.ID))
 		if l == nil {
 			http.Error(w, lease.ErrLeaseNotFound.Error(), http.StatusNotFound)
@@ -126,6 +129,14 @@ func (h *leaseHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			resp.LeaseTimeToLiveResponse.Keys = kbs
 		}
 
+		// The leasor could be demoted if leader changed during lookup.
+		// We should return error to force retry instead of returning
+		// incorrect remaining TTL.
+		if l.Demoted() {
+			http.Error(w, lease.ErrNotPrimary.Error(), http.StatusInternalServerError)
+			return
+		}
+
 		v, err = resp.Marshal()
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)

tests/integration/v3_lease_test.go

@@ -22,6 +22,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
@@ -30,8 +32,10 @@ import (
 	"go.etcd.io/etcd/api/v3/mvccpb"
 	"go.etcd.io/etcd/api/v3/v3rpc/rpctypes"
 	"go.etcd.io/etcd/client/pkg/v3/testutil"
+	clientv3 "go.etcd.io/etcd/client/v3"
 	framecfg "go.etcd.io/etcd/tests/v3/framework/config"
 	"go.etcd.io/etcd/tests/v3/framework/integration"
+	gofail "go.etcd.io/gofail/runtime"
 )
 
 // TestV3LeasePromote ensures the newly elected leader can promote itself
@@ -1046,6 +1050,78 @@ func TestV3LeaseRecoverKeyWithMutipleLease(t *testing.T) {
 	}
 }
 
+func TestV3LeaseTimeToLiveWithLeaderChanged(t *testing.T) {
+	t.Run("normal", func(subT *testing.T) {
+		testV3LeaseTimeToLiveWithLeaderChanged(subT, "beforeLookupWhenLeaseTimeToLive")
+	})
+
+	t.Run("forward", func(subT *testing.T) {
+		testV3LeaseTimeToLiveWithLeaderChanged(subT, "beforeLookupWhenForwardLeaseTimeToLive")
+	})
+}
+
+func testV3LeaseTimeToLiveWithLeaderChanged(t *testing.T, fpName string) {
+	if len(gofail.List()) == 0 {
+		t.Skip("please run 'make gofail-enable' before running the test")
+	}
+
+	integration.BeforeTest(t)
+
+	clus := integration.NewCluster(t, &integration.ClusterConfig{Size: 3})
+	defer clus.Terminate(t)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	oldLeadIdx := clus.WaitLeader(t)
+	followerIdx := (oldLeadIdx + 1) % 3
+
+	followerMemberID := clus.Members[followerIdx].ID()
+
+	oldLeadC := clus.Client(oldLeadIdx)
+
+	leaseResp, err := oldLeadC.Grant(ctx, 100)
+	require.NoError(t, err)
+
+	require.NoError(t, gofail.Enable(fpName, `sleep("3s")`))
+	t.Cleanup(func() {
+		terr := gofail.Disable(fpName)
+		if terr != nil && terr != gofail.ErrDisabled {
+			t.Fatalf("failed to disable %s: %v", fpName, terr)
+		}
+	})
+
+	readyCh := make(chan struct{})
+	errCh := make(chan error, 1)
+
+	var targetC *clientv3.Client
+	switch fpName {
+	case "beforeLookupWhenLeaseTimeToLive":
+		targetC = oldLeadC
+	case "beforeLookupWhenForwardLeaseTimeToLive":
+		targetC = clus.Client((oldLeadIdx + 2) % 3)
+	default:
+		t.Fatalf("unsupported %s failpoint", fpName)
+	}
+
+	go func() {
+		<-readyCh
+		time.Sleep(1 * time.Second)
+
+		_, merr := oldLeadC.MoveLeader(ctx, uint64(followerMemberID))
+		assert.NoError(t, gofail.Disable(fpName))
+		errCh <- merr
+	}()
+
+	close(readyCh)
+
+	ttlResp, err := targetC.TimeToLive(ctx, leaseResp.ID)
+	require.NoError(t, err)
+	require.GreaterOrEqual(t, int64(100), ttlResp.TTL)
+
+	require.NoError(t, <-errCh)
+}
+
 // acquireLeaseAndKey creates a new lease and creates an attached key.
 func acquireLeaseAndKey(clus *integration.Cluster, key string) (int64, error) {
 	// create lease

tests/robustness/makefile.mk

@@ -36,15 +36,15 @@ GOFAIL_VERSION = $(shell cd tools/mod && go list -m -f {{.Version}} go.etcd.io/g
 
 .PHONY: gofail-enable
 gofail-enable: install-gofail
-	gofail enable server/etcdserver/ server/storage/backend/ server/storage/mvcc/ server/storage/wal/ server/etcdserver/api/v3rpc/
+	gofail enable server/etcdserver/ server/lease/leasehttp server/storage/backend/ server/storage/mvcc/ server/storage/wal/ server/etcdserver/api/v3rpc/
 	cd ./server && go get go.etcd.io/gofail@${GOFAIL_VERSION}
 	cd ./etcdutl && go get go.etcd.io/gofail@${GOFAIL_VERSION}
 	cd ./etcdctl && go get go.etcd.io/gofail@${GOFAIL_VERSION}
 	cd ./tests && go get go.etcd.io/gofail@${GOFAIL_VERSION}
 
 .PHONY: gofail-disable
 gofail-disable: install-gofail
-	gofail disable server/etcdserver/ server/storage/backend/ server/storage/mvcc/ server/storage/wal/ server/etcdserver/api/v3rpc/
+	gofail disable server/etcdserver/ server/lease/leasehttp server/storage/backend/ server/storage/mvcc/ server/storage/wal/ server/etcdserver/api/v3rpc/
 	cd ./server && go mod tidy
 	cd ./etcdutl && go mod tidy
 	cd ./etcdctl && go mod tidy