使用kubeadm方式搭建k8s集群

1.搭建前准备

三台centos7服务器（虚拟机），ip地址如下

192.168.135.148（node节点）

192.168.135.149（node节点）

192.168.135.150（master节点）

首先确保三台机器关闭发了防火墙、swap交换分区和selinux ，并且可以互相访问

临时关闭：

setenforce 0
swapoff -a
systemctl stop firewalld

永久关闭：

swap：

cat /etc/fstab
找到  /dev/mapper/centos-swap swap  注释掉，也可使用以下命令
sed -i "s/\/dev\/mapper\/centos-swap/#\/dev\/mapper\/centos-swap/" /etc/fstab
reboot

防火墙：

systemctl disable firewalld

selinux：

cat /etc/sysconfig/selinux

将SELINUX=enforcing 改为disabled  或者permissive
disabled完全关闭，permissive会提示警告
这里我选择permissive
sed -i "s/SELINUX=enforcing/SELINUX=permissive/g" /etc/sysconfig/selinux
reboot

2.安装k8s集群的必须组件kubeadm、kubectl、kubelet

kubeadm可以理解为官方提供的集群部署工具，一般也只会在部署时用到

kubectl时操作集群的客户端软件，他通过与kubelet交互，达到操作集群资源、管理集群的目的

kubelet是集群服务，也是集群中的一个非常重要的组件，负责节点上pod的创建、管理等，同时也负责监控节点的信息

开始安装：

　　每个服务器中安装

　　在/etc/yum.repos.d/下新建文件kubernetes.repo，并将[kubernetes]z直到EOF前的信息复制进去，也可直接执行命令

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

#创建完成后直接执行yum安装
yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet

注：此处使用的资源为cetos7 64位最新稳定资源，各组件版本号如下

　　启用shell的自动补全功能

yum install -y bash-completion
source /usr/share/bash-completion/bash_completion

此处参考的官网步骤，稍微有点问题，kubectl不会自动补全

　　每个服务器安装docker，执行以下命令，详情不再赘述

yum install yum-utils -y
yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
yum install docker-ce docker-ce-cli containerd.io -y
systemctl start docker
####设置cgroup为systemd
cat <<EOF > /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
EOF
systemctl daemon-reload && systemctl restart docker

注：这一步的设置cgroup driver很重要，如果k8s的cgroup driver与docker不一致，安装将会失败

验证修改是否成功 docker info | grep Cgroup

3.安装完成后使用国内源初始化master节点，创建配置文件存储位置，分发配置文件到每个node节点

kubeadm init --image-repository registry.aliyuncs.com/google_containers
mkdir -p $HOME/.kube
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config
sed -i "14a\- --allocate-node-cidrs=true" /etc/kubernetes/manifests/kube-controller-manager.yaml
sed -i "14a\ - --cluster-cidr=10.244.0.0/16" /etc/kubernetes/manifests/kube-controller-manager.yaml

在当前登录的用户家目录下创建配置文件存放目录，推荐使用root进行，另外两步sed是开启flannel插件的相关配置，如果不安装flannel插件可以先忽略（如果没有网络插件，集群其实是不能部署pod的）

这一步会稍微等几分钟，等待master节点初始化完成后，会给出一个命令，将这个命令复制到其他要加入集群的node节点中执行，我这里就是 192.168.135148和192.168.135.149

kubeadm join 192.168.135.150:6443 --token ktwbcb.5u2u5uf48yyjfj60 \
    --discovery-token-ca-cert-hash sha256:8f0ca1579e36c35f0e557134d1909213cb03d424a6ecc415b4f27262942674bd

这是我的token，每个人的不一样，并且token只在24小时之内有效，如果过期了要生成新的token，查看以下命令

# 生成一个永不过期的token，不建议使用
kubeadm token create --ttl 0 --print-join-command

###生成新token
kubeadm token create --print-join-command

接下来的操作只在node节点执行

scp root@192.168.135.150:/etc/kubernetes/admin.conf /etc/kubernetes/
systemctl restart kubelet
mkdir -p $HOME/.kube
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config

这一步是将master节点的配置文件拷贝到node节点，然后同样在家目录下创建目录

scp是将主机的该文件拷贝到本机，ip地址不同记得更换

4.部署flannel网络插件

之前说过，没有网络插件的话不能够创建pod，提供集群内的互相通信，网络插件就是干这个用的

k8s的网络插件有很多，这里我选择的flannel ，flannel有官方提供的部署文件，能够“科学”上网的话可以自行下载，我这里提供的flannel插件只适用于k8s1.21~1.25版本（目前的k8s版本也就到1.23 ，官方说的）

首先新建/etc/kubernetes/flannel/目录，创建kube-flannel.yml文件，复制以下的内容。如果不用cat的话记得去掉EOF其实这个文件放在哪里都可以，但是为了方便管理，还是把它放在kubernetes的目录下

mkdir -p /etc/kubernetes/flannel/
cat << EOF > /etc/kubernetes/flannel/kube-flannel.yml
---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: psp.flannel.unprivileged
  annotations:
    seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
    seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
    apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default
    apparmor.security.beta.kubernetes.io/defaultProfileName: runtime/default
spec:
  privileged: false
  volumes:
  - configMap
  - secret
  - emptyDir
  - hostPath
  allowedHostPaths:
  - pathPrefix: "/etc/cni/net.d"
  - pathPrefix: "/etc/kube-flannel"
  - pathPrefix: "/run/flannel"
  readOnlyRootFilesystem: false
  # Users and groups
  runAsUser:
    rule: RunAsAny
  supplementalGroups:
    rule: RunAsAny
  fsGroup:
    rule: RunAsAny
  # Privilege Escalation
  allowPrivilegeEscalation: false
  defaultAllowPrivilegeEscalation: false
  # Capabilities
  allowedCapabilities: ['NET_ADMIN', 'NET_RAW']
  defaultAddCapabilities: []
  requiredDropCapabilities: []
  # Host namespaces
  hostPID: false
  hostIPC: false
  hostNetwork: true
  hostPorts:
  - min: 0
    max: 65535
  # SELinux
  seLinux:
    # SELinux is unused in CaaSP
    rule: 'RunAsAny'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: flannel
rules:
- apiGroups: ['extensions']
  resources: ['podsecuritypolicies']
  verbs: ['use']
  resourceNames: ['psp.flannel.unprivileged']
- 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-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: flannel
  namespace: kube-system
---
kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
  namespace: kube-system
  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-system
  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: rancher/mirrored-flannelcni-flannel-cni-plugin:v1.0.0
        command:
        - cp
        args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        volumeMounts:
        - name: cni-plugin
          mountPath: /opt/cni/bin
      - name: install-cni
        image: quay.io/coreos/flannel:v0.15.1
        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: quay.io/coreos/flannel:v0.15.1
        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
        volumeMounts:
        - name: run
          mountPath: /run/flannel
        - name: flannel-cfg
          mountPath: /etc/kube-flannel/
      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
EOF