Remove unexpected route from route list

backend/hostgw/hostgw_network.go

@@ -117,6 +117,7 @@ func (n *network) handleSubnetEvents(batch []subnet.Event) {
 					log.Errorf("Error deleting route to %v: %v", evt.Lease.Subnet, err)
 					continue
 				}
+				n.removeFromRouteList(routeList[0])
 			}
 			if len(routeList) > 0 && routeList[0].Gw.Equal(route.Gw) {
 				// Same Dst and same Gw, keep it and do not attempt to add it.

backend/hostgw/hostgw_network_test.go

@@ -0,0 +1,56 @@
+package hostgw
+
+import (
+	"net"
+	"runtime"
+	"testing"
+
+	"github.com/coreos/flannel/backend"
+	"github.com/coreos/flannel/pkg/ip"
+	"github.com/coreos/flannel/subnet"
+	"github.com/vishvananda/netlink"
+	"github.com/vishvananda/netns"
+)
+
+func TestRouteCache(t *testing.T) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+	origns, _ := netns.Get()
+	defer origns.Close()
+	newns, _ := netns.New()
+	netns.Set(newns)
+	defer newns.Close()
+
+	lo, err := netlink.LinkByName("lo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := netlink.AddrAdd(lo, &netlink.Addr{IPNet: &net.IPNet{IP: net.ParseIP("127.0.0.1"), Mask: net.CIDRMask(32, 32)}}); err != nil {
+		t.Fatal(err)
+	}
+	if err := netlink.LinkSetUp(lo); err != nil {
+		t.Fatal(err)
+	}
+	nw := network{extIface: &backend.ExternalInterface{Iface: &net.Interface{Index: lo.Attrs().Index}}}
+	gw1, gw2 := ip.FromIP(net.ParseIP("127.0.0.1")), ip.FromIP(net.ParseIP("127.0.0.2"))
+	subnet1 := ip.IP4Net{IP: ip.FromIP(net.ParseIP("192.168.0.0")), PrefixLen: 24}
+	nw.handleSubnetEvents([]subnet.Event{
+		{Type: subnet.EventAdded, Lease: subnet.Lease{Subnet: subnet1, Attrs: subnet.LeaseAttrs{PublicIP: gw1, BackendType: "host-gw"}}},
+	})
+	if len(nw.rl) != 1 {
+		t.Fatal(nw.rl)
+	}
+	if !routeEqual(nw.rl[0], netlink.Route{Dst: subnet1.ToIPNet(), Gw: gw1.ToIP()}) {
+		t.Fatal(nw.rl[0])
+	}
+	// change gateway of previous route
+	nw.handleSubnetEvents([]subnet.Event{
+		{Type: subnet.EventAdded, Lease: subnet.Lease{
+			Subnet: subnet1, Attrs: subnet.LeaseAttrs{PublicIP: gw2, BackendType: "host-gw"}}}})
+	if len(nw.rl) != 1 {
+		t.Fatal(nw.rl)
+	}
+	if !routeEqual(nw.rl[0], netlink.Route{Dst: subnet1.ToIPNet(), Gw: gw2.ToIP()}) {
+		t.Fatal(nw.rl[0])
+	}
+}