mirror of
https://github.com/k3s-io/kubernetes.git
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300 lines
12 KiB
Go
300 lines
12 KiB
Go
/*
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Copyright 2020 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package network
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import (
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"context"
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"fmt"
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"strings"
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"time"
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"github.com/onsi/ginkgo"
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v1 "k8s.io/api/core/v1"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/util/intstr"
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"k8s.io/apimachinery/pkg/util/wait"
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clientset "k8s.io/client-go/kubernetes"
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"k8s.io/kubernetes/test/e2e/framework"
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e2enode "k8s.io/kubernetes/test/e2e/framework/node"
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e2epod "k8s.io/kubernetes/test/e2e/framework/pod"
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e2eservice "k8s.io/kubernetes/test/e2e/framework/service"
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e2eskipper "k8s.io/kubernetes/test/e2e/framework/skipper"
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)
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const (
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serviceName = "svc-udp"
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podClient = "pod-client"
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podBackend1 = "pod-server-1"
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podBackend2 = "pod-server-2"
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srcPort = 12345
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)
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// Linux NAT uses conntrack to perform NAT, everytime a new
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// flow is seen, a connection is created in the conntrack table, and it
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// is being used by the NAT module.
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// Each entry in the conntrack table has associated a timeout, that removes
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// the connection once it expires.
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// UDP is a connectionless protocol, so the conntrack module tracking functions
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// are not very advanced.
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// It uses a short timeout (30 sec by default) that is renewed if there are new flows
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// matching the connection. Otherwise it expires the entry.
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// This behaviour can cause issues in Kubernetes when one entry on the conntrack table
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// is never expired because the sender does not stop sending traffic, but the pods or
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// endpoints were deleted, blackholing the traffic
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// In order to mitigate this problem, Kubernetes delete the stale entries:
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// - when an endpoint is removed
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// - when a service goes from no endpoints to new endpoint
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// Ref: https://api.semanticscholar.org/CorpusID:198903401
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// Boye, Magnus. “Netfilter Connection Tracking and NAT Implementation.” (2012).
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var _ = SIGDescribe("Conntrack", func() {
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fr := framework.NewDefaultFramework("conntrack")
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type nodeInfo struct {
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name string
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nodeIP string
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}
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var (
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cs clientset.Interface
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ns string
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clientNodeInfo, serverNodeInfo nodeInfo
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)
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logContainsFn := func(text string) wait.ConditionFunc {
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return func() (bool, error) {
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logs, err := e2epod.GetPodLogs(cs, ns, podClient, podClient)
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if err != nil {
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// Retry the error next time.
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return false, nil
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}
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if !strings.Contains(string(logs), text) {
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return false, nil
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}
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return true, nil
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}
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}
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ginkgo.BeforeEach(func() {
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cs = fr.ClientSet
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ns = fr.Namespace.Name
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nodes, err := e2enode.GetBoundedReadySchedulableNodes(cs, 2)
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framework.ExpectNoError(err)
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if len(nodes.Items) < 2 {
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e2eskipper.Skipf(
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"Test requires >= 2 Ready nodes, but there are only %v nodes",
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len(nodes.Items))
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}
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ips := e2enode.CollectAddresses(nodes, v1.NodeInternalIP)
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clientNodeInfo = nodeInfo{
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name: nodes.Items[0].Name,
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nodeIP: ips[0],
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}
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serverNodeInfo = nodeInfo{
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name: nodes.Items[1].Name,
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nodeIP: ips[1],
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}
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})
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ginkgo.It("should be able to preserve UDP traffic when server pod cycles for a NodePort service", func() {
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// TODO(#91236): Remove once the test is debugged and fixed.
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// dump conntrack table for debugging
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defer dumpConntrack(cs)
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// Create a NodePort service
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udpJig := e2eservice.NewTestJig(cs, ns, serviceName)
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ginkgo.By("creating a UDP service " + serviceName + " with type=NodePort in " + ns)
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udpService, err := udpJig.CreateUDPService(func(svc *v1.Service) {
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svc.Spec.Type = v1.ServiceTypeNodePort
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svc.Spec.Ports = []v1.ServicePort{
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{Port: 80, Name: "udp", Protocol: v1.ProtocolUDP, TargetPort: intstr.FromInt(80)},
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}
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})
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framework.ExpectNoError(err)
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// Create a pod in one node to create the UDP traffic against the NodePort service every 5 seconds
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ginkgo.By("creating a client pod for probing the service " + serviceName)
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clientPod := newAgnhostPod(podClient, "")
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clientPod.Spec.NodeName = clientNodeInfo.name
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cmd := fmt.Sprintf(`date; for i in $(seq 1 3000); do echo "$(date) Try: ${i}"; echo hostname | nc -u -w 5 -p %d %s %d; echo; done`, srcPort, serverNodeInfo.nodeIP, udpService.Spec.Ports[0].NodePort)
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clientPod.Spec.Containers[0].Command = []string{"/bin/sh", "-c", cmd}
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clientPod.Spec.Containers[0].Name = podClient
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fr.PodClient().CreateSync(clientPod)
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// Read the client pod logs
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logs, err := e2epod.GetPodLogs(cs, ns, podClient, podClient)
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framework.ExpectNoError(err)
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framework.Logf("Pod client logs: %s", logs)
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// Add a backend pod to the service in the other node
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ginkgo.By("creating a backend pod " + podBackend1 + " for the service " + serviceName)
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serverPod1 := newAgnhostPod(podBackend1, "netexec", fmt.Sprintf("--udp-port=%d", 80))
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serverPod1.Labels = udpJig.Labels
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serverPod1.Spec.NodeName = serverNodeInfo.name
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fr.PodClient().CreateSync(serverPod1)
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// Waiting for service to expose endpoint.
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err = validateEndpointsPorts(cs, ns, serviceName, portsByPodName{podBackend1: {80}})
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framework.ExpectNoError(err, "failed to validate endpoints for service %s in namespace: %s", serviceName, ns)
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// Note that the fact that Endpoints object already exists, does NOT mean
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// that iptables (or whatever else is used) was already programmed.
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// Additionally take into account that UDP conntract entries timeout is
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// 30 seconds by default.
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// Based on the above check if the pod receives the traffic.
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ginkgo.By("checking client pod connected to the backend 1 on Node IP " + serverNodeInfo.nodeIP)
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if err := wait.PollImmediate(5*time.Second, time.Minute, logContainsFn(podBackend1)); err != nil {
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logs, err = e2epod.GetPodLogs(cs, ns, podClient, podClient)
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framework.ExpectNoError(err)
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framework.Logf("Pod client logs: %s", logs)
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framework.Failf("Failed to connect to backend 1")
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}
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// Create a second pod
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ginkgo.By("creating a second backend pod " + podBackend2 + " for the service " + serviceName)
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serverPod2 := newAgnhostPod(podBackend2, "netexec", fmt.Sprintf("--udp-port=%d", 80))
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serverPod2.Labels = udpJig.Labels
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serverPod2.Spec.NodeName = serverNodeInfo.name
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fr.PodClient().CreateSync(serverPod2)
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// and delete the first pod
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framework.Logf("Cleaning up %s pod", podBackend1)
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fr.PodClient().DeleteSync(podBackend1, metav1.DeleteOptions{}, framework.DefaultPodDeletionTimeout)
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// Waiting for service to expose endpoint.
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err = validateEndpointsPorts(cs, ns, serviceName, portsByPodName{podBackend2: {80}})
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framework.ExpectNoError(err, "failed to validate endpoints for service %s in namespace: %s", serviceName, ns)
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// Check that the second pod keeps receiving traffic
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// UDP conntrack entries timeout is 30 sec by default
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ginkgo.By("checking client pod connected to the backend 2 on Node IP " + serverNodeInfo.nodeIP)
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if err := wait.PollImmediate(5*time.Second, time.Minute, logContainsFn(podBackend2)); err != nil {
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logs, err = e2epod.GetPodLogs(cs, ns, podClient, podClient)
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framework.ExpectNoError(err)
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framework.Logf("Pod client logs: %s", logs)
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framework.Failf("Failed to connect to backend 2")
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}
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})
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ginkgo.It("should be able to preserve UDP traffic when server pod cycles for a ClusterIP service", func() {
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// TODO(#91236): Remove once the test is debugged and fixed.
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// dump conntrack table for debugging
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defer dumpConntrack(cs)
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// Create a ClusterIP service
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udpJig := e2eservice.NewTestJig(cs, ns, serviceName)
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ginkgo.By("creating a UDP service " + serviceName + " with type=ClusterIP in " + ns)
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udpService, err := udpJig.CreateUDPService(func(svc *v1.Service) {
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svc.Spec.Type = v1.ServiceTypeClusterIP
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svc.Spec.Ports = []v1.ServicePort{
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{Port: 80, Name: "udp", Protocol: v1.ProtocolUDP, TargetPort: intstr.FromInt(80)},
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}
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})
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framework.ExpectNoError(err)
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// Create a pod in one node to create the UDP traffic against the ClusterIP service every 5 seconds
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ginkgo.By("creating a client pod for probing the service " + serviceName)
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clientPod := newAgnhostPod(podClient, "")
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clientPod.Spec.NodeName = clientNodeInfo.name
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cmd := fmt.Sprintf(`date; for i in $(seq 1 3000); do echo "$(date) Try: ${i}"; echo hostname | nc -u -w 5 -p %d %s %d; echo; done`, srcPort, udpService.Spec.ClusterIP, udpService.Spec.Ports[0].Port)
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clientPod.Spec.Containers[0].Command = []string{"/bin/sh", "-c", cmd}
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clientPod.Spec.Containers[0].Name = podClient
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fr.PodClient().CreateSync(clientPod)
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// Read the client pod logs
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logs, err := e2epod.GetPodLogs(cs, ns, podClient, podClient)
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framework.ExpectNoError(err)
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framework.Logf("Pod client logs: %s", logs)
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// Add a backend pod to the service in the other node
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ginkgo.By("creating a backend pod " + podBackend1 + " for the service " + serviceName)
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serverPod1 := newAgnhostPod(podBackend1, "netexec", fmt.Sprintf("--udp-port=%d", 80))
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serverPod1.Labels = udpJig.Labels
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serverPod1.Spec.NodeName = serverNodeInfo.name
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fr.PodClient().CreateSync(serverPod1)
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// Waiting for service to expose endpoint.
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err = validateEndpointsPorts(cs, ns, serviceName, portsByPodName{podBackend1: {80}})
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framework.ExpectNoError(err, "failed to validate endpoints for service %s in namespace: %s", serviceName, ns)
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// Note that the fact that Endpoints object already exists, does NOT mean
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// that iptables (or whatever else is used) was already programmed.
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// Additionally take into account that UDP conntract entries timeout is
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// 30 seconds by default.
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// Based on the above check if the pod receives the traffic.
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ginkgo.By("checking client pod connected to the backend 1 on Node IP " + serverNodeInfo.nodeIP)
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if err := wait.PollImmediate(5*time.Second, time.Minute, logContainsFn(podBackend1)); err != nil {
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logs, err = e2epod.GetPodLogs(cs, ns, podClient, podClient)
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framework.ExpectNoError(err)
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framework.Logf("Pod client logs: %s", logs)
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framework.Failf("Failed to connect to backend 1")
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}
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// Create a second pod
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ginkgo.By("creating a second backend pod " + podBackend2 + " for the service " + serviceName)
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serverPod2 := newAgnhostPod(podBackend2, "netexec", fmt.Sprintf("--udp-port=%d", 80))
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serverPod2.Labels = udpJig.Labels
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serverPod2.Spec.NodeName = serverNodeInfo.name
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fr.PodClient().CreateSync(serverPod2)
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// and delete the first pod
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framework.Logf("Cleaning up %s pod", podBackend1)
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fr.PodClient().DeleteSync(podBackend1, metav1.DeleteOptions{}, framework.DefaultPodDeletionTimeout)
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// Waiting for service to expose endpoint.
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err = validateEndpointsPorts(cs, ns, serviceName, portsByPodName{podBackend2: {80}})
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framework.ExpectNoError(err, "failed to validate endpoints for service %s in namespace: %s", serviceName, ns)
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// Check that the second pod keeps receiving traffic
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// UDP conntrack entries timeout is 30 sec by default
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ginkgo.By("checking client pod connected to the backend 2 on Node IP " + serverNodeInfo.nodeIP)
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if err := wait.PollImmediate(5*time.Second, time.Minute, logContainsFn(podBackend2)); err != nil {
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logs, err = e2epod.GetPodLogs(cs, ns, podClient, podClient)
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framework.ExpectNoError(err)
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framework.Logf("Pod client logs: %s", logs)
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framework.Failf("Failed to connect to backend 2")
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}
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})
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})
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func dumpConntrack(cs clientset.Interface) {
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// Dump conntrack table of each node for troubleshooting using the kube-proxy pods
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namespace := "kube-system"
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pods, err := cs.CoreV1().Pods(namespace).List(context.TODO(), metav1.ListOptions{})
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if err != nil || len(pods.Items) == 0 {
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framework.Logf("failed to list kube-proxy pods in namespace: %s", namespace)
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return
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}
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cmd := "conntrack -L"
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for _, pod := range pods.Items {
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if strings.Contains(pod.Name, "kube-proxy") {
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stdout, err := framework.RunHostCmd(namespace, pod.Name, cmd)
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if err != nil {
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framework.Logf("Failed to dump conntrack table of node %s: %v", pod.Spec.NodeName, err)
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continue
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}
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framework.Logf("conntrack table of node %s: %s", pod.Spec.NodeName, stdout)
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}
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}
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}
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