VDiff: Make max diff duration upgrade/downgrade safe (#14995)

Signed-off-by: Matt Lord <[email protected]>

go/vt/vtctl/workflow/server.go

@@ -1720,6 +1720,21 @@ func (s *Server) VDiffCreate(ctx context.Context, req *vtctldatapb.VDiffCreateRe
 		tabletTypesStr = discovery.InOrderHint + tabletTypesStr
 	}
 
+	// This is a pointer so there's no ZeroValue in the message
+	// and an older v18 client will not provide it.
+	if req.MaxDiffDuration == nil {
+		req.MaxDiffDuration = &vttimepb.Duration{}
+	}
+	// The other vttime.Duration vars should not be nil as the
+	// client should always provide them, but we check anyway to
+	// be safe.
+	if req.FilteredReplicationWaitTime == nil {
+		req.FilteredReplicationWaitTime = &vttimepb.Duration{}
+	}
+	if req.WaitUpdateInterval == nil {
+		req.WaitUpdateInterval = &vttimepb.Duration{}
+	}
+
 	options := &tabletmanagerdatapb.VDiffOptions{
 		PickerOptions: &tabletmanagerdatapb.VDiffPickerOptions{
 			TabletTypes: tabletTypesStr,

go/vt/vtctl/workflow/server_test.go

@@ -27,16 +27,17 @@ import (
 
 	"vitess.io/vitess/go/mysql/collations"
 	"vitess.io/vitess/go/mysql/config"
-	"vitess.io/vitess/go/vt/sqlparser"
-
 	"vitess.io/vitess/go/sqltypes"
 	"vitess.io/vitess/go/test/utils"
+	"vitess.io/vitess/go/vt/sqlparser"
+	"vitess.io/vitess/go/vt/topo/memorytopo"
 	"vitess.io/vitess/go/vt/topo/topoproto"
 	"vitess.io/vitess/go/vt/vttablet/tmclient"
 
 	binlogdatapb "vitess.io/vitess/go/vt/proto/binlogdata"
 	querypb "vitess.io/vitess/go/vt/proto/query"
 	topodatapb "vitess.io/vitess/go/vt/proto/topodata"
+	vtctldatapb "vitess.io/vitess/go/vt/proto/vtctldata"
 )
 
 type fakeTMC struct {
@@ -167,3 +168,36 @@ func TestCheckReshardingJournalExistsOnTablet(t *testing.T) {
 		})
 	}
 }
+
+// TestVDiffCreate performs some basic tests of the VDiffCreate function
+// to ensure that it behaves as expected given a specific request.
+func TestVDiffCreate(t *testing.T) {
+	ctx := context.Background()
+	ts := memorytopo.NewServer(ctx, "cell")
+	tmc := &fakeTMC{}
+	s := NewServer(ts, tmc, collations.MySQL8(), sqlparser.NewTestParser(), config.DefaultMySQLVersion)
+
+	tests := []struct {
+		name    string
+		req     *vtctldatapb.VDiffCreateRequest
+		wantErr string
+	}{
+		{
+			name:    "no values",
+			req:     &vtctldatapb.VDiffCreateRequest{},
+			wantErr: "node doesn't exist: keyspaces/shards", // We did not provide any keyspace or shard
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.VDiffCreate(ctx, tt.req)
+			if tt.wantErr != "" {
+				require.EqualError(t, err, tt.wantErr)
+				return
+			}
+			require.NoError(t, err)
+			require.NotNil(t, got)
+			require.NotEmpty(t, got.UUID)
+		})
+	}
+}