Fix traceflow spec validation logic.

Currently, when some traceflow spec error happens, the status of such
traceflows will be "Running", not "Failed". This is because some validation
logic is located at wrong places. I fixed this problem by moving them to the
right place.

Signed-off-by: shi0rik0 <anguuan@outlook.com>

pkg/agent/controller/traceflow/traceflow_controller.go

@@ -300,16 +300,6 @@ func (c *Controller) startTraceflow(tf *crdv1alpha1.Traceflow) error {
 		return err
 	}
 
-	liveTraffic := tf.Spec.LiveTraffic
-	if tf.Spec.Source.Pod == "" && tf.Spec.Destination.Pod == "" {
-		klog.Errorf("Traceflow %s has neither source nor destination Pod specified", tf.Name)
-		return nil
-	}
-	if tf.Spec.Source.Pod == "" && !liveTraffic {
-		klog.Errorf("Traceflow %s does not have source Pod specified", tf.Name)
-		return nil
-	}
-
 	receiverOnly := false
 	var pod, ns string
 	if tf.Spec.Source.Pod != "" {
@@ -327,6 +317,8 @@ func (c *Controller) startTraceflow(tf *crdv1alpha1.Traceflow) error {
 	podInterfaces := c.interfaceStore.GetContainerInterfacesByPod(pod, ns)
 	isSender := len(podInterfaces) > 0 && !receiverOnly
 
+	liveTraffic := tf.Spec.LiveTraffic
+
 	var packet, matchPacket *binding.Packet
 	var ofPort uint32
 	if len(podInterfaces) > 0 {

pkg/controller/traceflow/controller.go

@@ -427,5 +427,14 @@ func (c *Controller) validateTraceflow(tf *crdv1alpha1.Traceflow) error {
 			return fmt.Errorf("using hostNetwork Pod as source in non-live-traffic Traceflow is not supported")
 		}
 	}
+
+	if tf.Spec.Source.Pod == "" && tf.Spec.Destination.Pod == "" {
+		return fmt.Errorf("Traceflow %s has neither source nor destination Pod specified", tf.Name)
+	}
+
+	if tf.Spec.Source.Pod == "" && !tf.Spec.LiveTraffic {
+		return fmt.Errorf("Traceflow %s does not have source Pod specified", tf.Name)
+	}
+
 	return nil
 }