kubeadm安装

什么时kubeadm

之前介绍过minikube的安装和基本使用，非常简单易用，当时是在单机环境中学习、验证k8s。但在集群的生产环境中，minikube就无用武之地了。

k8s的集群安装、部署非常复杂，需要专业的知识。为了简化，k8s社区出现了一个专门在集群中安装k8s的工具，就是kubeadm。

kubeadm和minikube类似，用镜像和容器封装k8s的组件，其目标是集群部署。

准备工作

既然是集群，所以至少需要两台电脑。可以在本地搭建虚拟机，也可以购买云服务器，如果是新用户，云服务器的价格并不贵。本人是购买了腾讯云的两台轻量应用服务器。注册，云服务器必须在一个地域和可用区。

1. 修改主机名称

   # 修改master节点，改为master；修改worker节点名称，改为worker01
   sudo vi /etc/hostname
   

2. 安装docker。本人的操作系统是Ubuntu，如何安装docker，参见本人的一篇文章：(Ubuntu上安装Docker_雨打夏夜的博客-CSDN博客

   docker安装完成后，对docker进行配置，把cgroup的驱动程序改为systemd，然后重启docker：

   cat <<EOF | sudo tee /etc/docker/daemon.json
   {
     "exec-opts": ["native.cgroupdriver=systemd"],
     "log-driver": "json-file",
     "log-opts": {
       "max-size": "100m"
     },
     "storage-driver": "overlay2"
   }
   EOF
   
   sudo systemctl enable docker
   sudo systemctl daemon-reload
   sudo systemctl restart docker
   

3. 修改iptables

   cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
   br_netfilter
   EOF
   
   cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
   net.bridge.bridge-nf-call-ip6tables = 1
   net.bridge.bridge-nf-call-iptables = 1
   net.ipv4.ip_forward=1 # better than modify /etc/sysctl.conf
   EOF
   
   sudo sysctl --system
   

4. 关闭Linux的swap分区，建议永久关闭

   sudo swapoff -a
   sudo sed -ri '/\sswap\s/s/^#?/#/' /etc/fstab
   

安装kubeadm

1. 修改软件源，分别执行

   sudo apt install -y apt-transport-https ca-certificates curl
   

   curl https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | sudo apt-key add -
   

   cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
   deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main
   EOF
   

   sudo apt update
   

2. 安装kubeadm、kubelet和kubectl，并指定版本：

   sudo apt install -y kubeadm=1.23.3-00 kubelet=1.23.3-00 kubectl=1.23.3-00
   

3. 安装完成之后，验证版本是否正确

   ubuntu@master:~$ kubeadm version
   kubeadm version: &version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.3", GitCommit:"816c97ab8cff8a1c72eccca1026f7820e93e0d25", GitTreeState:"clean", BuildDate:"2022-01-25T21:24:08Z", GoVersion:"go1.17.6", Compiler:"gc", Platform:"linux/amd64"}
   
   ubuntu@master:~$ kubectl version --short
   Client Version: v1.23.3
   Server Version: v1.23.3
   

4. 锁定版本

   sudo apt-mark hold kubeadm kubelet kubectl
   

下载 k8s组件镜像

1. 从阿里云仓库中下载相关镜像，使用下面的脚本，脚本文件名称任意，比如：kubeadm.sh，放在当前执行目录下。

   repo=registry.aliyuncs.com/google_containers
   
   for name in `kubeadm config images list --kubernetes-version v1.23.3`; do
   
       src_name=${name#k8s.gcr.io/}
       src_name=${src_name#coredns/}
   
       docker pull $repo/$src_name
   
       docker tag $repo/$src_name $name
       docker rmi $repo/$src_name
   done
   

2. 给脚本文件加权限

   chmode 777 kubeadm.sh
   

3. 执行脚本，下载镜像

   ./kubeadm.sh
   

4. 镜像下载完成后，查看镜像相关信息：

   ubuntu@master:~$ docker images
   REPOSITORY                                       TAG       IMAGE ID       CREATED         SIZE
   k8s.gcr.io/kube-apiserver                        v1.23.3   f40be0088a83   7 months ago    135MB
   k8s.gcr.io/kube-controller-manager               v1.23.3   b07520cd7ab7   7 months ago    125MB
   k8s.gcr.io/kube-scheduler                        v1.23.3   99a3486be4f2   7 months ago    53.5MB
   k8s.gcr.io/kube-proxy                            v1.23.3   9b7cc9982109   7 months ago    112MB
   k8s.gcr.io/etcd                                  3.5.1-0   25f8c7f3da61   10 months ago   293MB
   k8s.gcr.io/coredns/coredns                       v1.8.6    a4ca41631cc7   11 months ago   46.8MB
   k8s.gcr.io/pause                                 3.6       6270bb605e12   12 months ago   683kB
   

   注意：镜像版本有要求，读者下载完成后，和上面的IMAGE ID对比下，确认是相同的镜像，否则可能安装失败。

master节点安装

1. 执行下面的命令

   sudo kubeadm init \
       --pod-network-cidr=10.10.0.0/16 \
       --apiserver-advertise-address=10.0.4.12 \
       --kubernetes-version=v1.23.3
   

   注意：apiserver-advertise-address的值，应该是读者自己电脑的局域网ip，或云服务器的内网ip。10.0.4.12就是我云服务器的内网ip。

2. 安装完成后，会看到如下提示，按照要求分别执行相关脚本

   Your Kubernetes control-plane has initialized successfully!
   
   To start using your cluster, you need to run the following as a regular user:
   
     mkdir -p $HOME/.kube
     sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
     sudo chown $(id -u):$(id -g) $HOME/.kube/config
   

3. 安装完成后另一个重要的提示如下，其他节点要加入该集群，要用到该指令：

   Then you can join any number of worker nodes by running the following on each as root:
   
   kubeadm join 10.0.4.12:6443 --token ka3rxd.i2qidqbz6n4rukem \
           --discovery-token-ca-cert-hash sha256:9ce266be50b57614e2a4b67db01eaf24fede7a3c5fdf6bb8b18a99348baed671 
   

4. 安装完成后，可使用kubectl version、kubectl get node检查版本和节点状态

   ubuntu@master:~$ kubectl version --short
   Client Version: v1.23.3
   Server Version: v1.23.3
   ubuntu@master:~$ kubectl get node
   NAME     STATUS     ROLES                  AGE     VERSION
   master   NotReady   control-plane,master   2m42s   v1.23.3
   

   Master 节点的状态是“NotReady”，是由于还缺少网络插件，集群的内部网络还没有正常运作。

Flannel 网络插件

1. Flannel网络插件，在Git仓库中：flannel/kube-flannel.yml at master · flannel-io/flannel · GitHub，对应的yml文件如下：

   注意：我修改了该yml文件中的“net-conf.json”字段，把 Network 改成刚才 kubeadm 的参数 --pod-network-cidr 设置的地址段。

   net-conf.json: |
    {
      "Network": "10.10.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
   

---
kind: Namespace
apiVersion: v1
metadata:
  name: kube-flannel
  labels:
    pod-security.kubernetes.io/enforce: privileged
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
rules:
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: flannel
subjects:
- kind: ServiceAccount
  name: flannel
  namespace: kube-flannel
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: flannel
  namespace: kube-flannel
---
kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
  namespace: kube-flannel
  labels:
    tier: node
    app: flannel
data:
  cni-conf.json: |
    {
      "name": "cbr0",
      "cniVersion": "0.3.1",
      "plugins": [
        {
          "type": "flannel",
          "delegate": {
            "hairpinMode": true,
            "isDefaultGateway": true
          }
        },
        {
          "type": "portmap",
          "capabilities": {
            "portMappings": true
          }
        }
      ]
    }
  net-conf.json: |
    {
      "Network": "10.10.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds
  namespace: kube-flannel
  labels:
    tier: node
    app: flannel
spec:
  selector:
    matchLabels:
      app: flannel
  template:
    metadata:
      labels:
        tier: node
        app: flannel
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/os
                operator: In
                values:
                - linux
      hostNetwork: true
      priorityClassName: system-node-critical
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni-plugin
       #image: flannelcni/flannel-cni-plugin:v1.1.0 for ppc64le and mips64le (dockerhub limitations may apply)
        image: docker.io/rancher/mirrored-flannelcni-flannel-cni-plugin:v1.1.0
        command:
        - cp
        args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        volumeMounts:
        - name: cni-plugin
          mountPath: /opt/cni/bin
      - name: install-cni
       #image: flannelcni/flannel:v0.19.2 for ppc64le and mips64le (dockerhub limitations may apply)
        image: docker.io/rancher/mirrored-flannelcni-flannel:v0.19.2
        command:
        - cp
        args:
        - -f
        - /etc/kube-flannel/cni-conf.json
        - /etc/cni/net.d/10-flannel.conflist
        volumeMounts:
        - name: cni
          mountPath: /etc/cni/net.d
        - name: flannel-cfg
          mountPath: /etc/kube-flannel/
      containers:
      - name: kube-flannel
       #image: flannelcni/flannel:v0.19.2 for ppc64le and mips64le (dockerhub limitations may apply)
        image: docker.io/rancher/mirrored-flannelcni-flannel:v0.19.2
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        resources:
          requests:
            cpu: "100m"
            memory: "50Mi"
          limits:
            cpu: "100m"
            memory: "50Mi"
        securityContext:
          privileged: false
          capabilities:
            add: ["NET_ADMIN", "NET_RAW"]
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: EVENT_QUEUE_DEPTH
          value: "5000"
        volumeMounts:
        - name: run
          mountPath: /run/flannel
        - name: flannel-cfg
          mountPath: /etc/kube-flannel/
        - name: xtables-lock
          mountPath: /run/xtables.lock
      volumes:
      - name: run
        hostPath:
          path: /run/flannel
      - name: cni-plugin
        hostPath:
          path: /opt/cni/bin
      - name: cni
        hostPath:
          path: /etc/cni/net.d
      - name: flannel-cfg
        configMap:
          name: kube-flannel-cfg
      - name: xtables-lock
        hostPath:
          path: /run/xtables.lock
          type: FileOrCreate

2. 将上面的yml文件放在当前目录下，执行下面的命令：

   kubectl apply -f kube-flannel.yml
   

   上面脚本执行完成后，要等待几分钟，等待相关镜像下载、容器启动。

3. 几分钟后，再看节点状态：

   ubuntu@master:~$ kubectl get node
   NAME     STATUS   ROLES                  AGE   VERSION
   master   Ready    control-plane,master   54m   v1.23.3
   

安装work节点

1. 参照【下载 k8s组件镜像】章节，在worker节点先下载相关镜像，可加快安装速度

2. 执行安装master后，提示出现的命令

   ubuntu@worker:~$ sudo kubeadm join 10.0.4.12:6443 --token ka3rxd.i2qidqbz6n4rukem         --discovery-token-ca-cert-hash sha256:9ce266be50b57614e2a4b67db01eaf24fede7a3c5fdf6bb8b18a99348baed671
   [preflight] Running pre-flight checks
   [preflight] Reading configuration from the cluster...
   [preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
   W0918 16:18:01.313202   19199 utils.go:69] The recommended value for "resolvConf" in "KubeletConfiguration" is: /run/systemd/resolve/resolv.conf; the provided value is: /run/systemd/resolve/resolv.conf
   [kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
   [kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
   [kubelet-start] Starting the kubelet
   [kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
   
   This node has joined the cluster:
   * Certificate signing request was sent to apiserver and a response was received.
   * The Kubelet was informed of the new secure connection details.
   
   Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
   

   注意：执行上面的命令，需要确认master节点主机的防火墙设置，对外开放6443端口。如果是自己的虚拟机，可以关闭防火墙，如果是云服务器，则在防火墙/安全组中放行6443端口。

3. 在master节点上执行如下命令kubectl get node：

   ubuntu@master:~$ kubectl get node
   NAME     STATUS   ROLES                  AGE     VERSION
   master   Ready    control-plane,master   64m     v1.23.3
   worker   Ready    <none>                 4m23s   v1.23.3
   

测试

1. 运行nginx测试：

   ubuntu@master:~$ kubectl run ngx --image=nginx:alpine
   pod/ngx created
   

2. 查看pod，nginx运行在worker节点上。

   ubuntu@master:~$ kubectl get pod -o wide
   NAME   READY   STATUS    RESTARTS   AGE   IP          NODE     NOMINATED NODE   READINESS GATES
   ngx    1/1     Running   0          18s   10.10.1.2   worker   <none>           <none>
   

安装完成。