test: add test-server to collect packet lost during upgrade

Makefile

@@ -26,6 +26,7 @@ build-go:
 	go mod tidy
 	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -buildmode=pie -o $(CURDIR)/dist/images/kube-ovn-cmd -ldflags $(GOLDFLAGS) -v ./cmd
 	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -buildmode=pie -o $(CURDIR)/dist/images/kube-ovn-webhook -ldflags $(GOLDFLAGS) -v ./cmd/webhook
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o $(CURDIR)/dist/images/test-server -ldflags $(GOLDFLAGS) -v ./test/server
 
 .PHONY: build-go-windows
 build-go-windows:
@@ -74,6 +75,10 @@ image-centos-compile:
 	docker buildx build --platform linux/amd64 --build-arg ARCH=amd64 -t $(REGISTRY)/centos7-compile:$(RELEASE_TAG) -o type=docker -f dist/images/compile/centos7/Dockerfile fastpath/
 	# docker buildx build --platform linux/amd64 --build-arg ARCH=amd64 -t $(REGISTRY)/centos8-compile:$(RELEASE_TAG) -o type=docker -f dist/images/compile/centos8/Dockerfile fastpath/
 
+.PHOONY: image-test
+image-test: build-go
+	docker buildx build --platform linux/amd64 --build-arg ARCH=amd64 -t $(REGISTRY)/test:$(RELEASE_TAG) -o type=docker -f dist/images/Dockerfile.test dist/images/
+
 .PHONY: release
 release: lint image-kube-ovn image-vpc-nat-gateway image-centos-compile
 

dist/images/Dockerfile.test

@@ -0,0 +1,14 @@
+FROM alpine:edge
+
+RUN set -ex \
+    && echo https://dl-cdn.alpinelinux.org/alpine/edge/testing >> /etc/apk/repositories \
+    && apk update \
+    && apk upgrade \
+    && apk add --no-cache \
+    bash iproute2 iptables iputils tcpdump conntrack-tools \
+    redis nginx qperf iperf3 net-tools curl
+
+WORKDIR /kube-ovn
+COPY test-server /kube-ovn/test-server
+COPY test-server.sh /kube-ovn/test-server.sh
+CMD bash test-server.sh

dist/images/test-server.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+nginx
+iperf3 -s

test/server/README.md

@@ -0,0 +1,58 @@
+# Test Server
+
+This server mainly focuses on test network break effect during kube-ovn upgrade or restart, but can also be extended to test network connectivity.
+
+## How test server test network break
+
+The test-server will use ping, iperf3 and curl to visit a specified address during upgrade or reload. Then it automatically collect metrics from 
+`/proc/net/snmp` and return code to calculate ICMP lost, TCP retransmit packets and TCP connection failure.
+
+```bash
+# Deploy a kubernetes cluster with kube-ovn
+make kind-init kind-install
+
+# Build and deploy test-server
+make image-test
+kind load docker-image --name kube-ovn kubeovn/test:v1.11.0
+kubectl apply -f test/server/test-server.yaml
+docker run -d --net=kind kubeovn/test:v1.11.0
+
+# Run test-server analysis tool in one terminal and reload kube-ovn in another terminal
+# terminal 1
+kubectl exec -it test-client -- ./test-server 100.64.0.1
+
+# terminal 2
+kubectl ko reload
+
+# Try with different address to test different path.
+```
+
+# Test result
+
+ICMP test result:
+
+| Scenario                          | Lost |
+|-----------------------------------|------|
+| Pod address within same node      | 0    |
+| ovn0 address with in same node    | 13   |
+| Node address the Pod runs on      | 15   |
+| Pod address in another node       | 4    |
+| ovn0 address with in another node | 21   |
+| Node address of anther node       | 16   |
+| Address outside the cluster       | 32   |
+
+TCP test result:
+
+| Scenario                        | Retransmit | Connection Failure | Note             |
+|---------------------------------|------------|--------------------|------------------|
+| Pod address in another node     | 38         | 1                  |                  |
+| Service address                 | 86         | 0                  |                  |
+| Address outside the cluster     | 4          | 1                  |                  |
+| External visit NodePort address |            |                    | Connection Reset |
+
+## TODO
+
+1. NodePort long connection will be reset which need further investigation.
+2. Traffic that go through ovn0 suffers higher lost, and it may be related to internal type port.
+3. Replace curl with ab to test high connection concurrency.
+4. Need to be tested in large scale cluster where kube-ovn reload might take much longer time.

test/server/server.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"fmt"
+	"k8s.io/klog/v2"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func ReadSnmp() (map[string]map[string]int, error) {
+	buf, err := os.ReadFile("/proc/net/snmp")
+	if err != nil {
+		return nil, err
+	}
+	snmp := make(map[string]map[string]int)
+	snmpLine := strings.Split(string(buf), "\n")
+	for index := range snmpLine {
+		if index%2 == 1 || len(snmpLine[index]) == 0 {
+			continue
+		}
+		keys := strings.Split(snmpLine[index], " ")
+		values := strings.Split(snmpLine[index+1], " ")
+		snmpType := strings.TrimSuffix(keys[0], ":")
+
+		for i := range keys {
+			if i == 0 {
+				snmp[snmpType] = make(map[string]int)
+				continue
+			}
+			v, _ := strconv.Atoi(values[i])
+			snmp[snmpType][keys[i]] = v
+		}
+	}
+	return snmp, err
+}
+
+func main() {
+	defer klog.Flush()
+	klog.Infof("start")
+	icmpDone := make(chan string)
+	tcpConnDone := make(chan string)
+	tcpRetransDone := make(chan string)
+	preSnmp, err := ReadSnmp()
+	if err != nil {
+		klog.Error(err)
+		return
+	}
+	preDiff := preSnmp["Icmp"]["OutEchos"] - preSnmp["Icmp"]["InEchoReps"]
+	preRetrans := preSnmp["Tcp"]["RetransSegs"]
+
+	go func() {
+		output, err := exec.Command("ping", "-D", "-O", "-c", "6000", "-i", "0.01", os.Args[1]).CombinedOutput()
+		klog.Infof("%s, %v", output, err)
+		icmpDone <- ""
+	}()
+
+	failedConnection := 0
+	totalConnection := 0
+	go func() {
+		startTime := time.Now()
+		for {
+			if time.Since(startTime) > 60*time.Second {
+				break
+			}
+			time.Sleep(100 * time.Millisecond)
+			totalConnection += 1
+			output, err := exec.Command("curl", "-m", "1", fmt.Sprintf("%s:80", os.Args[1])).CombinedOutput()
+			if err != nil {
+				klog.Infof("%s, %v", output, err)
+				failedConnection += 1
+			}
+		}
+		tcpConnDone <- ""
+	}()
+
+	go func() {
+		output, err := exec.Command("iperf3", "-c", os.Args[1], "-b", "10M", "-t", "60", "-l", "1K").CombinedOutput()
+		klog.Infof("%s, %v", output, err)
+		tcpRetransDone <- ""
+	}()
+
+	<-icmpDone
+	<-tcpConnDone
+	<-tcpRetransDone
+
+	curSnmp, err := ReadSnmp()
+	if err != nil {
+		klog.Error(err)
+		return
+	}
+	curDiff := curSnmp["Icmp"]["OutEchos"] - curSnmp["Icmp"]["InEchoReps"]
+	curRetrans := curSnmp["Tcp"]["RetransSegs"]
+	klog.Infof("lost %d icmp response", curDiff-preDiff)
+	klog.Infof("retrans %d tcp segment", curRetrans-preRetrans)
+	klog.Infof("%d failed connection, %d total connection", failedConnection, totalConnection)
+
+	klog.Infof("Done")
+}

test/server/test-server.yaml

@@ -0,0 +1,52 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: test-server
+  labels:
+    env: test-server
+spec:
+  containers:
+    - name: test-server
+      image: kubeovn/test:v1.11.0
+      imagePullPolicy: IfNotPresent
+  nodeSelector:
+    kubernetes.io/hostname: kube-ovn-control-plane
+
+---
+
+apiVersion: v1
+kind: Pod
+metadata:
+  name: test-client
+  labels:
+    env: test-client
+spec:
+  containers:
+    - name: test-client
+      image: kubeovn/test:v1.11.0
+      imagePullPolicy: IfNotPresent
+  nodeSelector:
+    kubernetes.io/hostname: kube-ovn-worker
+
+---
+
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    env: test-server
+  name: test-server
+  namespace: default
+spec:
+  ports:
+    - port: 80
+      protocol: TCP
+      targetPort: 80
+      name: nginx
+    - port: 5201
+      protocol: TCP
+      targetPort: 5201
+      name: iperf
+  selector:
+    env: test-server
+  type: NodePort