一、服务器资源

至少两台服务器，作为matser节点及node1节点
约定：
pod网段：10.244.0.0/16
service网段：10.10.0.0/16

二、Docker安装

不同版本的k8s对于docker版本是有要求的，k8s1.23版本推荐的docker版本最高为20.10，因此这里我们安装20.10版本docker

1.更新软件包 & 安装前置依赖

sudo apt update
sudo apt install apt-transport-https ca-certificates curl gnupg-agent software-properties-common

2.导入源仓库的 GPG key

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

3.将 Docker APT 软件源添加到你的系统

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

4.查看可用的docker版本

apt-cache madison docker-ce

5.安装指定的docker版本

sudo apt update
sudo apt install docker-ce=5:20.10.0~3-0~ubuntu-bionic docker-ce-cli=5:20.10.0~3-0~ubuntu-bionic containerd.io

6.查看docker 是否安装正常

docker --version

7.配置docker(重要)

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

8.换源

cp /etc/apt/sources.list /etc/apt/sources.list.bak
vim /etc/apt/sources.list

更换为以下内容（不同系统版本内容不一致）

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse

9.设置docker自启动

sudo systemctl daemon-reload && sudo systemctl restart docker && sudo systemctl enable docker

三、其他准备

1.关闭交换分区

swapoff --all
sed -i -r '/swap/ s/^/#/' /etc/fstab

2.关闭防火墙

ufw disable

3.配置源，安装依赖

apt-get update && apt-get install -y apt-transport-https curl
cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://mirrors.ustc.edu.cn/kubernetes/apt kubernetes-xenial main
EOF

4.获取kubernetes 的key

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

四 安装

1.安装1.23版本

apt-get update
apt-get install kubelet=1.23.1-00 kubeadm=1.23.1-00 kubectl=1.23.1-00

2.添加自启动，配置阻止软件自更新

systemctl enable kubelet
apt-mark hold kubelet kubeadm kubectl 

3.初始化节点，其中172.11.1.123为节点ip

kubeadm init \
--apiserver-advertise-address 172.11.1.123 \
--image-repository registry.cn-hangzhou.aliyuncs.com/google_containers \
--pod-network-cidr=10.244.0.0/16 \
--service-cidr=10.96.0.0/12 \
--ignore-preflight-errors=SystemVerification

4.配置证书

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

5.测试

kubectl get node

五、添加节点到集群中

1.配置Flannel通信(master节点)

创建yml文件kube-flannel.yml，内容如下

---
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:
  - get
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
- apiGroups:
  - "networking.k8s.io"
  resources:
  - clustercidrs
  verbs:
  - list
  - watch
---
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-system
- 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": "10.244.0.0/16",
      "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: docker.io/flannel/flannel-cni-plugin:v1.1.2
       #image: docker.io/rancher/mirrored-flannelcni-flannel-cni-plugin:v1.1.2
        command:
        - cp
        args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        volumeMounts:
        - name: cni-plugin
          mountPath: /opt/cni/bin
      - name: install-cni
        image: docker.io/flannel/flannel:v0.20.2
       #image: docker.io/rancher/mirrored-flannelcni-flannel:v0.20.2
        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: docker.io/flannel/flannel:v0.20.2
       #image: docker.io/rancher/mirrored-flannelcni-flannel:v0.20.2
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        resources:
          requests:
            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

master节点执行命令

kubectl create -f kube-flannel.yml

2.节点加入

master节点执行以下命令

kubeadm token create --print-join-command

将返回结果复制到node节点执行

3.报错处理

如果报错类似如下：

[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
        [ERROR FileAvailable--etc-kubernetes-kubelet.conf]: /etc/kubernetes/kubelet.conf already exists
        [ERROR Port-10250]: Port 10250 is in use
        [ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

在node节点执行kubeadm reset后再重新执行加入节点的命令：

kubeadm reset

如果报错如下：The connection to the server localhost:8080 was refused - did you specify the right host or port?
将master节点的/etc/kubernetes/admin.conf文件拷贝到node节点同样位置，并执行

echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> /etc/profile
source /etc/profile

查看节点状态

kubectl get nodes

六、测试CoreDNS可用性

1.创建容器

kubectl run busybox --image busybox:1.28 --restart=Never --rm -it busybox -- sh

2.测试是否可以正常解析 （容器中执行）

nslookup kubernetes.default.svc.cluster.local

结果如下：