e2e/network_policy: using PollImmediate for intra pod connectivity probes

test/e2e/network/netpol/kubemanager.go

@@ -19,29 +19,30 @@ package netpol
 import (
 	"context"
 	"fmt"
-	"net"
-	"strconv"
-	"strings"
-
 	v1 "k8s.io/api/core/v1"
 	networkingv1 "k8s.io/api/networking/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/wait"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/kubernetes/test/e2e/framework"
 	e2epod "k8s.io/kubernetes/test/e2e/framework/pod"
 	netutils "k8s.io/utils/net"
+	"net"
+	"strconv"
+	"strings"
+	"time"
 )
 
-// probeConnectivityArgs is set of arguments for a probeConnectivity
-type probeConnectivityArgs struct {
-	nsFrom         string
-	podFrom        string
-	containerFrom  string
-	addrTo         string
-	protocol       v1.Protocol
-	toPort         int
-	timeoutSeconds int
-}
+// defaultPollIntervalSeconds [seconds] is the default value for which the Prober will wait before attempting next attempt.
+const defaultPollIntervalSeconds = 2
+
+// defaultPollTimeoutSeconds [seconds] is the default timeout when polling on probes.
+// using this value leads to a minimum of 2 attempts for every probe
+const defaultPollTimeoutSeconds = 1
+
+// maxPollTimeoutSeconds [seconds] is the max timeout when polling on probes, this should only be used when expect a
+// successful probe; use defaultPollTimeout otherwise
+const maxPollTimeoutSeconds = 10
 
 // TestPod represents an actual running pod. For each Pod defined by the model,
 // there will be a corresponding TestPod. TestPod includes some runtime info
@@ -181,9 +182,21 @@ func (k *kubeManager) probeConnectivity(args *probeConnectivityArgs) (bool, stri
 	}
 
 	commandDebugString := fmt.Sprintf("kubectl exec %s -c %s -n %s -- %s", args.podFrom, args.containerFrom, args.nsFrom, strings.Join(cmd, " "))
-	stdout, stderr, err := k.executeRemoteCommand(args.nsFrom, args.podFrom, args.containerFrom, cmd)
+
+	attempt := 0
+
+	err := wait.PollImmediate(time.Duration(args.pollIntervalSeconds)*time.Second, time.Duration(args.pollTimeoutSeconds)*time.Second,
+		func() (bool, error) {
+			stdout, stderr, err := k.executeRemoteCommand(args.nsFrom, args.podFrom, args.containerFrom, cmd)
+			if err != nil {
+				framework.Logf("retrying probe #%d :: %s/%s -> %s: error when running command: err - %v /// stdout - %s /// stderr - %s", attempt+1, args.nsFrom, args.podFrom, args.addrTo, err, stdout, stderr)
+				attempt++
+				return false, nil
+			}
+			return true, nil
+		})
+
 	if err != nil {
-		framework.Logf("%s/%s -> %s: error when running command: err - %v /// stdout - %s /// stderr - %s", args.nsFrom, args.podFrom, args.addrTo, err, stdout, stderr)
 		return false, commandDebugString, nil
 	}
 	return true, commandDebugString, nil
@@ -290,3 +303,16 @@ func getProbeTimeoutSeconds() int {
 func getWorkers() int {
 	return 3
 }
+
+// getPollInterval returns the value for which the Prober will wait before attempting next attempt.
+func getPollIntervalSeconds() int {
+	return defaultPollIntervalSeconds
+}
+
+// getPollTimeout returns the timeout for polling on probes.
+func getPollTimeoutSeconds(useMaxPollTimout bool) int {
+	if useMaxPollTimout {
+		return maxPollTimeoutSeconds
+	}
+	return defaultPollTimeoutSeconds
+}

test/e2e/network/netpol/probe.go

@@ -25,6 +25,19 @@ import (
 	netutils "k8s.io/utils/net"
 )
 
+// probeConnectivityArgs is set of arguments for a probeConnectivity
+type probeConnectivityArgs struct {
+	nsFrom              string
+	podFrom             string
+	containerFrom       string
+	addrTo              string
+	protocol            v1.Protocol
+	toPort              int
+	timeoutSeconds      int
+	pollIntervalSeconds int
+	pollTimeoutSeconds  int
+}
+
 // decouple us from k8smanager.go
 type Prober interface {
 	probeConnectivity(args *probeConnectivityArgs) (bool, string, error)
@@ -32,12 +45,13 @@ type Prober interface {
 
 // ProbeJob packages the data for the input of a pod->pod connectivity probe
 type ProbeJob struct {
-	PodFrom        TestPod
-	PodTo          TestPod
-	PodToServiceIP string
-	ToPort         int
-	ToPodDNSDomain string
-	Protocol       v1.Protocol
+	PodFrom           TestPod
+	PodTo             TestPod
+	PodToServiceIP    string
+	ToPort            int
+	ToPodDNSDomain    string
+	Protocol          v1.Protocol
+	UseMaxPollTimeout bool
 }
 
 // ProbeJobResults packages the data for the results of a pod->pod connectivity probe
@@ -54,16 +68,22 @@ func ProbePodToPodConnectivity(prober Prober, allPods []TestPod, dnsDomain strin
 	jobs := make(chan *ProbeJob, size)
 	results := make(chan *ProbeJobResults, size)
 	for i := 0; i < getWorkers(); i++ {
-		go probeWorker(prober, jobs, results, getProbeTimeoutSeconds())
+		go probeWorker(prober, jobs, results)
 	}
 	for _, podFrom := range allPods {
 		for _, podTo := range allPods {
+			useMaxPollTimeout := false
+			// we only want to use max poll timeout for the probes where we expect connectivity from "podFrom" to "podTo".
+			if testCase.Reachability.Expected.Get(podFrom.PodString().String(), podTo.PodString().String()) {
+				useMaxPollTimeout = true
+			}
 			jobs <- &ProbeJob{
-				PodFrom:        podFrom,
-				PodTo:          podTo,
-				ToPort:         testCase.ToPort,
-				ToPodDNSDomain: dnsDomain,
-				Protocol:       testCase.Protocol,
+				PodFrom:           podFrom,
+				PodTo:             podTo,
+				ToPort:            testCase.ToPort,
+				ToPodDNSDomain:    dnsDomain,
+				Protocol:          testCase.Protocol,
+				UseMaxPollTimeout: useMaxPollTimeout,
 			}
 		}
 	}
@@ -91,7 +111,7 @@ func ProbePodToPodConnectivity(prober Prober, allPods []TestPod, dnsDomain strin
 
 // probeWorker continues polling a pod connectivity status, until the incoming "jobs" channel is closed, and writes results back out to the "results" channel.
 // it only writes pass/fail status to a channel and has no failure side effects, this is by design since we do not want to fail inside a goroutine.
-func probeWorker(prober Prober, jobs <-chan *ProbeJob, results chan<- *ProbeJobResults, timeoutSeconds int) {
+func probeWorker(prober Prober, jobs <-chan *ProbeJob, results chan<- *ProbeJobResults) {
 	defer ginkgo.GinkgoRecover()
 	for job := range jobs {
 		podFrom := job.PodFrom
@@ -110,13 +130,15 @@ func probeWorker(prober Prober, jobs <-chan *ProbeJob, results chan<- *ProbeJobR
 
 		// TODO make this work on dual-stack clusters...
 		connected, command, err := prober.probeConnectivity(&probeConnectivityArgs{
-			nsFrom:         podFrom.Namespace,
-			podFrom:        podFrom.Name,
-			containerFrom:  podFrom.ContainerName,
-			addrTo:         job.PodTo.ServiceIP,
-			protocol:       job.Protocol,
-			toPort:         job.ToPort,
-			timeoutSeconds: timeoutSeconds,
+			nsFrom:              podFrom.Namespace,
+			podFrom:             podFrom.Name,
+			containerFrom:       podFrom.ContainerName,
+			addrTo:              job.PodTo.ServiceIP,
+			protocol:            job.Protocol,
+			toPort:              job.ToPort,
+			timeoutSeconds:      getProbeTimeoutSeconds(),
+			pollIntervalSeconds: getPollIntervalSeconds(),
+			pollTimeoutSeconds:  getPollTimeoutSeconds(job.UseMaxPollTimeout),
 		})
 		result := &ProbeJobResults{
 			Job:         job,

test/e2e/network/netpol/test_helper.go

@@ -111,10 +111,13 @@ func waitForHTTPServers(k *kubeManager, model *Model) error {
 func ValidateOrFail(k8s *kubeManager, testCase *TestCase) {
 	ginkgo.By("Validating reachability matrix...")
 
-	// 1st try
+	// 1st try, exponential backoff (starting at 1s) will happen for every probe to accommodate infra that might be
+	// network-congested, as is common in some GH actions or other heavily oversubscribed CI systems.
 	ginkgo.By("Validating reachability matrix... (FIRST TRY)")
 	ProbePodToPodConnectivity(k8s, k8s.AllPods(), k8s.DNSDomain(), testCase)
-	// 2nd try, in case first one failed
+
+	// the aforementioned individual probe's exponential retries (introduced in january 2023) might be able to obviate
+	//  this step, let's investigate removing this massive secondary polling of the matrix some day.
 	if _, wrong, _, _ := testCase.Reachability.Summary(ignoreLoopback); wrong != 0 {
 		framework.Logf("failed first probe %d wrong results ... retrying (SECOND TRY)", wrong)
 		ProbePodToPodConnectivity(k8s, k8s.AllPods(), k8s.DNSDomain(), testCase)