k8s集群搭建网上已经有多种成熟的方案，例如如kubekey、kubespray。而这些方案大多数也是对kubeadm进行了封装而已。本文就通过具体的实例，手动使用kubeadm一步一步搭建k8s集群。

本文中部署的k8s实例版本号为1.20.4，其他版本部署流程基本相同。

本章节主要介绍k8s集群的第一个节点（master）的初始化流程，后续章节会陆续介绍其他master节点或者worker节点如何加入集群。如果读者仅仅想体验k8s的功能，那么单节点就可以运行了。

目录

1. 整体架构

2 部署master1节点

2.1 环境初始化

2.2 部署k8s二进制

2.3 初始化主节点

---

1. 整体架构

• master1：192.168.56.10

• master2：192.168.56.11

• master3：192.168.56.12

• node1：192.168.56.13

• node2：192.168.56.14

2 部署master1节点

2.1 环境初始化

1. 关闭防火墙、虚拟交换分区、selinux

# 关闭防火墙
sudo systemctl stop firewalld && systemctl disable firewalld
sudo systemctl stop ufw && systemctl disable ufw
# 关闭虚拟交换（注释fstab中swap配置）
sudo swapoff -a
sudo sed -i /^[^#]*swap*/s/^/\#/g /etc/fstab

1. 设置/etc/hosts

192.168.56.10 master1
192.168.56.11 master2
192.168.56.12 master3
192.168.56.13 node1
192.168.56.14 node2

1. 部署docker

#一键式部署docker
curl -fsSL https://get.docker.com | sudo bash -s docker --mirror Aliyun
sudo systemctl enable docker && sudo systemctl restart docker

1. 安装必备软件

sudo apt-get install socat conntrack ebtables ipset ipvsadm

1. 设置hostname

sudo hostnamectl set-hostname master1

2.2 部署k8s二进制

1. 将kubelet、kubectl、kubeadm拷贝到/usr/local/bin路径下，并赋予执行权限

curl https://dl.k8s.io/v1.20.4/kubernetes-node-linux-amd64.tar.gz -o ./kubernetes-node-linux-amd64.tar.gz
tar -zxvf kubernetes-client-linux-amd64.tar.gz -C ./ 
# 部署kubeadm
sudo cp ./kubernetes/node/bin/kubeadm /usr/local/bin/ && sudo chmod +x /usr/local/bin/kubeadm
# 部署kubectl
sudo cp ./kubernetes/node/bin/kubectl /usr/local/bin/ && sudo chmod +x /usr/local/bin/kubectl
# 部署kubelet
sudo cp ./kubernetes/node/bin/kubelet /usr/local/bin/ && sudo chmod +x /usr/local/bin/kubelet

1. 生成kubelet服务/etc/systemd/system/kubelet.service

[Unit]
Description=kubelet: The Kubernetes Node Agent
Documentation=http://kubernetes.io/docs/

[Service]
CPUAccounting=true
MemoryAccounting=true
ExecStart=/usr/local/bin/kubelet
Restart=always
StartLimitInterval=0
RestartSec=10

[Install]
WantedBy=multi-user.target

1. 生成kubelet配置文件/etc/systemd/system/kubelet.service.d/10-kubeadm.conf

# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generate at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/default/kubelet
Environment="KUBELET_EXTRA_ARGS=--node-ip=192.168.56.10 --hostname-override=master1"
ExecStart=
ExecStart=/usr/local/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

1. 使能kubelet

sudo systemctl disable kubelet 
sudo systemctl enable kubelet 
sudo ln -snf /usr/local/bin/kubelet /usr/bin/kubelet

2.3 初始化主节点

1. 使用kubeadm初始化master。该过程会部署控制面相关组件etcd、kube-apiserver、kube-controller-manager、kube-scheduler

sudo kubeadm init --pod-network-cidr=10.244.0.0/16 --ignore-preflight-errors=NumCPU --apiserver-advertise-address=192.168.56.10 --image-repository registry.aliyuncs.com/google_containers

1. 部署网络插件flannel（或者calico），编辑network-plugin.yaml

---
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']
  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:
  labels:
    k8s-app: flannel
  name: flannel
rules:
  - apiGroups: ['extensions']
    resources: ['podsecuritypolicies']
    verbs: ['use']
    resourceNames: ['psp.flannel.unprivileged']
  - 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:
  labels:
    k8s-app: flannel
  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
    k8s-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
    k8s-app: flannel
spec:
  selector:
    matchLabels:
      app: flannel
      k8s-app: flannel
  template:
    metadata:
      labels:
        tier: node
        app: flannel
        k8s-app: flannel
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                  - key: kubernetes.io/os
                    operator: In
                    values:
                      - linux
      hostNetwork: true
      tolerations:
      - operator: Exists
        effect: NoSchedule
      priorityClassName: system-node-critical
      serviceAccountName: flannel
      initContainers:
      - name: install-cni-plugin
        args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        command:
        - cp
        image: flannel/flannel-cni-plugin:v1.1.2
        volumeMounts:
        - mountPath: /opt/cni/bin
          name: cni-plugin
      - name: install-cni
        image: flannel/flannel:v0.21.3
        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: {{ .FlannelImage }}
        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/
        - mountPath: /run/xtables.lock
          name: 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: xtables-lock
          hostPath:
           path: /run/xtables.lock
           type: FileOrCreate
        - name: flannel-cfg
          configMap:
            name: kube-flannel-cfg

1. 部署flannel

sudo kubectl apply -f network-plugin.yaml