deflake e2e session affinity tests

Executing commands in pods is expensive in terms of time and the
execution time is unpredictable and random.
The session affinity tests send several http requests from a pod
to check that the session is sticky. Instead of executing one
http request at a time, we can execute several requests from the
pod at one time and process the output.

Author: aojea

test/e2e/network/service.go

@@ -114,20 +114,26 @@ type portsByPodName map[string][]int
 // return false only in case of unexpected errors.
 func checkAffinity(execPod *v1.Pod, serviceIP string, servicePort int, shouldHold bool) bool {
 	serviceIPPort := net.JoinHostPort(serviceIP, strconv.Itoa(servicePort))
-	cmd := fmt.Sprintf(`curl -q -s --connect-timeout 2 http://%s/`, serviceIPPort)
+	curl := fmt.Sprintf(`curl -q -s --connect-timeout 2 http://%s/`, serviceIPPort)
+	cmd := fmt.Sprintf("for i in $(seq 0 %d); do echo; %s ; done", AffinityConfirmCount, curl)
 	timeout := AffinityTimeout
 	if execPod == nil {
 		timeout = LoadBalancerPollTimeout
 	}
 	var tracker affinityTracker
-	if pollErr := wait.PollImmediate(framework.Poll, timeout, func() (bool, error) {
+	// interval considering a maximum of 2 seconds per connection
+	interval := 2 * AffinityConfirmCount * time.Second
+	if pollErr := wait.PollImmediate(interval, timeout, func() (bool, error) {
 		if execPod != nil {
 			stdout, err := framework.RunHostCmd(execPod.Namespace, execPod.Name, cmd)
 			if err != nil {
 				framework.Logf("Failed to get response from %s. Retry until timeout", serviceIPPort)
 				return false, nil
 			}
-			tracker.recordHost(stdout)
+			hosts := strings.Split(stdout, "\n")
+			for _, host := range hosts {
+				tracker.recordHost(strings.TrimSpace(host))
+			}
 		} else {
 			rawResponse := GetHTTPContent(serviceIP, servicePort, timeout, "")
 			tracker.recordHost(rawResponse.String())