sdn: try cleaning up OVS rules even if sandbox is gone

If a sandbox is deleted underneath kubernetes its netns will
be gone and its veth interface will be deleted by the kernel.
That means we can't inspect the veth for its IP address and
other details, which are used to remove OVS flows for the
interface.

But we've already got code to find out the IP using the
sandbox ID which kubelet passes down to us.  Let's use
that code to at least delete the stale OVS flows.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1518684

Author: dcbw

pkg/network/node/ovscontroller.go

@@ -402,11 +402,17 @@ func (oc *ovsController) TearDownPod(hostVeth, podIP, sandboxID string) error {
 		podIP = ip
 	}
 
-	if err := oc.cleanupPodFlows(podIP); err != nil {
+	err := oc.cleanupPodFlows(podIP)
+	if err != nil {
 		return err
 	}
-	_ = oc.SetPodBandwidth(hostVeth, -1, -1)
-	return oc.ovs.DeletePort(hostVeth)
+
+	// veth may have already been destroyed if the container was deleted out-of-band
+	if hostVeth != "" {
+		_ = oc.SetPodBandwidth(hostVeth, -1, -1)
+		err = oc.ovs.DeletePort(hostVeth)
+	}
+	return err
 }
 
 func policyNames(policies []networkapi.EgressNetworkPolicy) string {

pkg/network/node/pod.go

@@ -679,23 +679,26 @@ func (m *podManager) teardown(req *cniserver.PodRequest) error {
 	defer PodOperationsLatency.WithLabelValues(PodOperationTeardown).Observe(sinceInMicroseconds(time.Now()))
 
 	netnsValid := true
-	if err := ns.IsNSorErr(req.Netns); err != nil {
+	err := ns.IsNSorErr(req.Netns)
+	if err != nil {
 		if _, ok := err.(ns.NSPathNotExistErr); ok {
 			glog.V(3).Infof("teardown called on already-destroyed pod %s/%s; only cleaning up IPAM", req.PodNamespace, req.PodName)
 			netnsValid = false
 		}
 	}
 
-	errList := []error{}
+	var hostVethName string
+	var podIP string
 	if netnsValid {
-		hostVethName, _, podIP, err := getVethInfo(req.Netns, podInterfaceName)
+		hostVethName, _, podIP, err = getVethInfo(req.Netns, podInterfaceName)
 		if err != nil {
 			return err
 		}
+	}
 
-		if err := m.ovs.TearDownPod(hostVethName, podIP, req.SandboxID); err != nil {
-			errList = append(errList, err)
-		}
+	errList := []error{}
+	if err := m.ovs.TearDownPod(hostVethName, podIP, req.SandboxID); err != nil {
+		errList = append(errList, err)
 	}
 
 	if err := m.ipamDel(req.SandboxID); err != nil {