Kubernetes 集群中 Ingress 故障的根因诊断

作者：scwang18，主要负责技术架构，在容器云方向颇有研究。

前言

KubeSphere 是青云开源的基于 Kubernetes 的云原生分布式操作系统，提供了比较炫酷的 Kubernetes 集群管理界面，我们团队用 KubeSphere 来作为开发平台。

本文记录了一次 KubeSphere 环境下的网络故障的解决过程。

现象

开发同学反馈自己搭建的 Harbor 仓库总是出问题，偶尔会报 net/http: TLS handshake timeout ，通过 curl 的方式访问 harbor.xxxx.cn ，也会随机频繁挂起。但是 ping 的反馈一切正常。

原因分析

接到错误报障后，经过了多轮分析，才最终定位到原因，应该是安装 KubeSphere 时，使用了最新版的 Kubernetes 1.23.1 。

虽然使用 ./kk version --show-supported-k8s 可以看到 KubeSphere 3.2.1 可以支持 Kubernetes 1.23.1 ，但实际上只是试验性支持，有坑的。

分析过程如下：

出现 Harbor registry 访问问题，下意识以为是 Harbor 部署有问题，但是在检查 Harbor core 的日志的时候，没有看到异常时有相应错误信息，甚至 info 级别的日志信息都没有。
又把目标放在 Harbor portal，查看访问日志，一样没有发现异常信息。
根据访问链，继续追查 kubesphere-router-kubesphere-system ，即 KubeSphere 版的 nginx ingress controller ，同样没有发现异常日志。
尝试在集群内其他 Pod 里访问 Harbor 的集群内 Service 地址，发现不会出现访问超时问题。初步判断是 KubeSphere 自带的 Ingress 的问题。
把 kubeSphere 自带的 Ingress Controller 关闭，安装 Kubernetes 官方推荐的 ingress-nginx-controller 版本，故障依旧，而且 Ingress 日志里也没有发现异常信息。
综合上面的分析，问题应该出现在客户端到 Ingress Controller 之间，我的 Ingress Controller 是通过 NodePort 方式暴露到集群外面。因此，测试其他通过 NodePort 暴露到集群外的 service，发现是一样的故障，至此，可以完全排除 Harbor 部署问题了，基本确定是客户端到 Ingress Controller 的问题。
外部客户端通过 NodePort 访问 Ingress Controller 时，会通过 kube-proxy 组件，分析 kube-proxy 的日志，发现告警信息

can’t set sysctl net/ipv4/vs/conn_reuse_mode, kernel version must be at least 4.1

这个告警信息是因为我的 centos 7.6 的内核版本过低，当前是 3.10.0-1160.21.1.el7.x86_64 ，与 Kubernetes 新版的 ipvs 存在兼容性问题。

可以通过升级操作系统的 kernel 版本可以解决。

升级完 kernel 后，Calico 启动不了，报以下错误信息

ipset v7.1: kernel and userspace incompatible: settype hash:ip,port with revision 6 not supported by userspace.

原因是安装 KubeSphere 时默认安装的 Calico 版本是 v3.20.0 , 这个版本不支持最新版的 Linux Kernel ，升级后的内核版本是 5.18.1-1.el7.elrepo.x86_64，calico 需要升级到 v3.23.0 以上版本。

升级完 Calico 版本后，Calico 继续报错

user "system:serviceaccount:kube-system:calico-node" cannot list resource "caliconodestatuses" in api group "crd.projectcalico.org"

还有另外一个错误信息，都是因为 clusterrole 的资源权限不足，可以通过修改 clusterrole 来解决问题。

至此，该莫名其妙的网络问题解决了。

解决过程

根据上面的分析，主要解决方案如下：

升级操作系统内核

使用阿里云的 yum 源

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
yum clean all && yum -y update

启用 elrepo 仓库

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm

安装最新版本内核

yum --enablerepo=elrepo-kernel install kernel-ml

查看系统上的所有可用内核

awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg

设置新的内核为 grub2 的默认版本

查看第4步返回的系统可用内核列表，不出意外第1个应该是最新安装的内核。

grub2-set-default 0

生成 grub 配置文件并重启

grub2-mkconfig -o /boot/grub2/grub.cfg
reboot now

验证

uname -r

升级 Calico

Kubernetes 上的 Calico 一般是使用 Daemonset 方式部署，我的集群里，Calico 的 Daemonset 名字是 calico-node。

直接输出为 yaml 文件，修改文件里的所有 image 版本号为最新版本 v3.23.1 。重新创建 Daemonset。

输出 yaml

kubectl -n kube-system get ds  calico-node -o yaml>calico-node.yaml

calico-node.yaml：

apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    k8s-app: calico-node
  name: calico-node
  namespace: kube-system
spec:
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      k8s-app: calico-node
  template:
    metadata:
      creationTimestamp: null
      labels:
        k8s-app: calico-node
    spec:
      containers:
      - env:
        - name: DATASTORE_TYPE
          value: kubernetes
        - name: WAIT_FOR_DATASTORE
          value: "true"
        - name: NODENAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        - name: CALICO_NETWORKING_BACKEND
          valueFrom:
            configMapKeyRef:
              key: calico_backend
              name: calico-config
        - name: CLUSTER_TYPE
          value: k8s,bgp
        - name: NODEIP
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: status.hostIP
        - name: IP_AUTODETECTION_METHOD
          value: can-reach=$(NODEIP)
        - name: IP
          value: autodetect
        - name: CALICO_IPV4POOL_IPIP
          value: Always
        - name: CALICO_IPV4POOL_VXLAN
          value: Never
        - name: FELIX_IPINIPMTU
          valueFrom:
            configMapKeyRef:
              key: veth_mtu
              name: calico-config
        - name: FELIX_VXLANMTU
          valueFrom:
            configMapKeyRef:
              key: veth_mtu
              name: calico-config
        - name: FELIX_WIREGUARDMTU
          valueFrom:
            configMapKeyRef:
              key: veth_mtu
              name: calico-config
        - name: CALICO_IPV4POOL_CIDR
          value: 10.233.64.0/18
        - name: CALICO_IPV4POOL_BLOCK_SIZE
          value: "24"
        - name: CALICO_DISABLE_FILE_LOGGING
          value: "true"
        - name: FELIX_DEFAULTENDPOINTTOHOSTACTION
          value: ACCEPT
        - name: FELIX_IPV6SUPPORT
          value: "false"
        - name: FELIX_HEALTHENABLED
          value: "true"
        envFrom:
        - configMapRef:
            name: kubernetes-services-endpoint
            optional: true
        image: calico/node:v3.23.1
        imagePullPolicy: IfNotPresent
        livenessProbe:
          exec:
            command:
            - /bin/calico-node
            - -felix-live
            - -bird-live
          failureThreshold: 6
          initialDelaySeconds: 10
          periodSeconds: 10
          successThreshold: 1
          timeoutSeconds: 10
        name: calico-node
        readinessProbe:
          exec:
            command:
            - /bin/calico-node
            - -felix-ready
            - -bird-ready
          failureThreshold: 3
          periodSeconds: 10
          successThreshold: 1
          timeoutSeconds: 10
        resources:
          requests:
            cpu: 250m
        securityContext:
          privileged: true
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /host/etc/cni/net.d
          name: cni-net-dir
        - mountPath: /lib/modules
          name: lib-modules
          readOnly: true
        - mountPath: /run/xtables.lock
          name: xtables-lock
        - mountPath: /var/run/calico
          name: var-run-calico
        - mountPath: /var/lib/calico
          name: var-lib-calico
        - mountPath: /var/run/nodeagent
          name: policysync
        - mountPath: /sys/fs/
          mountPropagation: Bidirectional
          name: sysfs
        - mountPath: /var/log/calico/cni
          name: cni-log-dir
          readOnly: true
      dnsPolicy: ClusterFirst
      hostNetwork: true
      initContainers:
      - command:
        - /opt/cni/bin/calico-ipam
        - -upgrade
        env:
        - name: KUBERNETES_NODE_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        - name: CALICO_NETWORKING_BACKEND
          valueFrom:
            configMapKeyRef:
              key: calico_backend
              name: calico-config
        envFrom:
        - configMapRef:
            name: kubernetes-services-endpoint
            optional: true
        image: calico/cni:v3.23.1
        imagePullPolicy: IfNotPresent
        name: upgrade-ipam
        resources: {}
        securityContext:
          privileged: true
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /var/lib/cni/networks
          name: host-local-net-dir
        - mountPath: /host/opt/cni/bin
          name: cni-bin-dir
      - command:
        - /opt/cni/bin/install
        env:
        - name: CNI_CONF_NAME
          value: 10-calico.conflist
        - name: CNI_NETWORK_CONFIG
          valueFrom:
            configMapKeyRef:
              key: cni_network_config
              name: calico-config
        - name: KUBERNETES_NODE_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        - name: CNI_MTU
          valueFrom:
            configMapKeyRef:
              key: veth_mtu
              name: calico-config
        - name: SLEEP
          value: "false"
        envFrom:
        - configMapRef:
            name: kubernetes-services-endpoint
            optional: true
        image: calico/cni:v3.23.1
        imagePullPolicy: IfNotPresent
        name: install-cni
        resources: {}
        securityContext:
          privileged: true
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /host/opt/cni/bin
          name: cni-bin-dir
        - mountPath: /host/etc/cni/net.d
          name: cni-net-dir
      - image: calico/pod2daemon-flexvol:v3.23.1
        imagePullPolicy: IfNotPresent
        name: flexvol-driver
        resources: {}
        securityContext:
          privileged: true
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - mountPath: /host/driver
          name: flexvol-driver-host
      nodeSelector:
        kubernetes.io/os: linux
      priorityClassName: system-node-critical
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      serviceAccount: calico-node
      serviceAccountName: calico-node
      terminationGracePeriodSeconds: 0
      tolerations:
      - effect: NoSchedule
        operator: Exists
      - key: CriticalAddonsOnly
        operator: Exists
      - effect: NoExecute
        operator: Exists
      volumes:
      - hostPath:
          path: /lib/modules
          type: ""
        name: lib-modules
      - hostPath:
          path: /var/run/calico
          type: ""
        name: var-run-calico
      - hostPath:
          path: /var/lib/calico
          type: ""
        name: var-lib-calico
      - hostPath:
          path: /run/xtables.lock
          type: FileOrCreate
        name: xtables-lock
      - hostPath:
          path: /sys/fs/
          type: DirectoryOrCreate
        name: sysfs
      - hostPath:
          path: /opt/cni/bin
          type: ""
        name: cni-bin-dir
      - hostPath:
          path: /etc/cni/net.d
          type: ""
        name: cni-net-dir
      - hostPath:
          path: /var/log/calico/cni
          type: ""
        name: cni-log-dir
      - hostPath:
          path: /var/lib/cni/networks
          type: ""
        name: host-local-net-dir
      - hostPath:
          path: /var/run/nodeagent
          type: DirectoryOrCreate
        name: policysync
      - hostPath:
          path: /usr/libexec/kubernetes/kubelet-plugins/volume/exec/nodeagent~uds
          type: DirectoryOrCreate
        name: flexvol-driver-host
  updateStrategy:
    rollingUpdate:
      maxSurge: 0
      maxUnavailable: 1
    type: RollingUpdate

ClusterRole

还需要修改 ClusterRole ，否则 Calico 会一直报权限错。

输出 yaml

kubectl get clusterrole calico-node -o yaml >calico-node-clusterrole.yaml

calico-node-clusterrole.yaml

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: calico-node
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - nodes
  - namespaces
  verbs:
  - get
- apiGroups:
  - discovery.k8s.io
  resources:
  - endpointslices
  verbs:
  - watch
  - list
- apiGroups:
  - ""
  resources:
  - endpoints
  - services
  verbs:
  - watch
  - list
  - get
- apiGroups:
  - ""
  resources:
  - configmaps
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
  - update
- apiGroups:
  - networking.k8s.io
  resources:
  - networkpolicies
  verbs:
  - watch
  - list
- apiGroups:
  - ""
  resources:
  - pods
  - namespaces
  - serviceaccounts
  verbs:
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - pods/status
  verbs:
  - patch
- apiGroups:
  - crd.projectcalico.org
  resources:
  - globalfelixconfigs
  - felixconfigurations
  - bgppeers
  - globalbgpconfigs
  - bgpconfigurations
  - ippools
  - ipamblocks
  - globalnetworkpolicies
  - globalnetworksets
  - networkpolicies
  - networksets
  - clusterinformations
  - hostendpoints
  - blockaffinities
  - caliconodestatuses
  - ipreservations
  verbs:
  - get
  - list
  - watch
- apiGroups:
  - crd.projectcalico.org
  resources:
  - ippools
  - felixconfigurations
  - clusterinformations
  verbs:
  - create
  - update
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - get
  - list
  - watch
- apiGroups:
  - crd.projectcalico.org
  resources:
  - bgpconfigurations
  - bgppeers
  verbs:
  - create
  - update
- apiGroups:
  - crd.projectcalico.org
  resources:
  - blockaffinities
  - ipamblocks
  - ipamhandles
  verbs:
  - get
  - list
  - create
  - update
  - delete
- apiGroups:
  - crd.projectcalico.org
  resources:
  - ipamconfigs
  verbs:
  - get
- apiGroups:
  - crd.projectcalico.org
  resources:
  - blockaffinities
  verbs:
  - watch
- apiGroups:
  - apps
  resources:
  - daemonsets
  verbs:
  - get

总结

这次奇怪的网络故障，最终原因还是因为 KubeSphere 的版本与 Kubernetes 的版本不匹配。所以工作环境要稳字为先，不要冒进使用最新的版本。否则会耽搁很多时间来解决莫名其妙的问题。