在书本上提到了kubernetes的两种安装方式，分别为kubeadm工具安装和二进制方式安装。下面分别来实践一下；
IP地址规划：

HOSTNAME	IP	角色	操作系统
K8S-node1	192.168.56.201	master	centos-7.9
K8S-node2	192.168.56.202	worker	centos-7.9
K8S-node3	192.168.56.203	worker	centos-7.9

准备阶段：

#设置每个机器自己的hostname
hostnamectl set-hostname xxx

# 将 SELinux 设置为 permissive 模式（相当于将其禁用）
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

#关闭swap
swapoff -a  
sed -ri 's/.*swap.*/#&/' /etc/fstab

#允许 iptables 检查桥接流量
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
EOF
sudo sysctl --system

kubeadm方式安装

安装docker

需要在三台设备上分别安装docker

sudo yum remove docker*
sudo yum install -y yum-utils

#配置docker的yum地址
wget -O /etc/yum.repos.d/docker-ce.repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo


#安装指定版本
sudo yum install -y docker-ce docker-ce-cli containerd.io

#	启动&开机启动docker
systemctl enable docker --now

# docker加速配置
sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["https://ke9h1pt4.mirror.aliyuncs.com"],
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF
sudo systemctl daemon-reload
sudo systemctl restart docker

注意，配置“exec-opts”选项，是因为kebernetes默认设置cgroup驱动为systemd，而docker服务的cgroup驱动为cgroupfs，从而导致后序kuberlet服务无法正常启动
registry-mirrors为镜像加速地址：可以通过阿里云的容器镜像服务，获取自己的加速器地址。

通过docker的安装包过程，能够看到安装的版本：

[root@k8s-node2 ~]# yum list installed |grep docker
containerd.io.x86_64               1.4.12-3.1.el7              @docker-ce-stable
docker-ce.x86_64                   3:20.10.12-3.el7            @docker-ce-stable
docker-ce-cli.x86_64               1:20.10.12-3.el7            @docker-ce-stable
docker-ce-rootless-extras.x86_64   20.10.12-3.el7              @docker-ce-stable
docker-scan-plugin.x86_64          0.12.0-3.el7                @docker-ce-stable
[root@k8s-node2 ~]# 

配置k8s yum源

#配置k8s的yum源地址，这里指定为阿里云的yum源
cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
   http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

在master上安装kubeadm kubelet和kubectl

 yum -y install kubeadm kubelet kubectl --disableexcludes=kubernetes

查看安装的版本：

[root@k8s-node1 ~]# yum list installed |grep kube*
cri-tools.x86_64                   1.19.0-0                    @kubernetes      
kubeadm.x86_64                     1.23.1-0                    @kubernetes      
kubectl.x86_64                     1.23.1-0                    @kubernetes      
kubelet.x86_64                     1.23.1-0                    @kubernetes      
kubernetes-cni.x86_64              0.8.7-0                     @kubernetes      
[root@k8s-node1 ~]# 

修改kubeadm的默认配置文件

kubeadm config print init-defaults > init-config.yaml

修改“init-config.yaml”配置文件内容：

apiVersion: kubeadm.k8s.io/v1beta3
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 192.168.56.201 #需要修改为master的主机名或IP地址
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  imagePullPolicy: IfNotPresent
  name: k8s-node1  #修改注册的node名称为k8s-node1
  taints: null
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta3
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns: {}
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/google_containers #修改默认拉取镜像的地址
kind: ClusterConfiguration
kubernetesVersion: 1.23.0 
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
  podSubnet: 192.168.0.0/16 #指定POD的子网地址
scheduler: {}

下载kubernetes的相关镜像

查看需要下载哪些镜像：

[root@k8s-node1 ~]# kubeadm config images list
k8s.gcr.io/kube-apiserver:v1.23.1
k8s.gcr.io/kube-controller-manager:v1.23.1
k8s.gcr.io/kube-scheduler:v1.23.1
k8s.gcr.io/kube-proxy:v1.23.1
k8s.gcr.io/pause:3.6
k8s.gcr.io/etcd:3.5.1-0
k8s.gcr.io/coredns/coredns:v1.8.6
[root@k8s-node1 ~]#

下载镜像：

[root@k8s-node1 ~]# kubeadm config images pull --config=init-config.yaml
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-apiserver:v1.23.0
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-controller-manager:v1.23.0
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-scheduler:v1.23.0
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-proxy:v1.23.0
[config/images] Pulled registry.aliyuncs.com/google_containers/pause:3.6
[config/images] Pulled registry.aliyuncs.com/google_containers/etcd:3.5.1-0
[config/images] Pulled registry.aliyuncs.com/google_containers/coredns:v1.8.6
[root@k8s-node1 ~]#

运行kubeadm init命令安装master节点

kubeadm init --config=init-config.yaml

查看输出：

[root@k8s-node1 ~]# kubeadm init --config=init-config.yaml
[init] Using Kubernetes version: v1.23.0
[preflight] Running pre-flight checks
        [WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s-node1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.56.201]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [k8s-node1 localhost] and IPs [192.168.56.201 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-node1 localhost] and IPs [192.168.56.201 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 11.505998 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.23" in namespace kube-system with the configuration for the kubelets in the cluster
NOTE: The "kubelet-config-1.23" naming of the kubelet ConfigMap is deprecated. Once the UnversionedKubeletConfigMap feature gate graduates to Beta the default name will become just "kubelet-config". Kubeadm upgrade will handle this transition transparently.
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node k8s-node1 as control-plane by adding the labels: [node-role.kubernetes.io/master(deprecated) node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node k8s-node1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

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

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.56.201:6443 --token abcdef.0123456789abcdef \
        --discovery-token-ca-cert-hash sha256:5d62fc27e71f83a104de94b73e3a77291056fb2cc483df6ebf7447440843e805 
[root@k8s-node1 ~]#

导出环境变量，为了永久生效可以将它添加到/etc/profile下

[root@k8s-node1 ~]# echo "KUBECONFIG=/etc/kubernetes/admin.conf" >> /etc/profile ;source /etc/profile
[root@k8s-node1 ~]# 

此时查看nodes能够看到只有一个节点：

[root@k8s-node1 ~]# kubectl get nodes
NAME        STATUS     ROLES                  AGE   VERSION
k8s-node1   NotReady   control-plane,master   12m   v1.23.1
[root@k8s-node1 ~]# 

将新的node加入集群

（1）在两台Worker上安装kubeadm和kubelet

yum -y install kubelet kubeadm --disableexcludes=kubernetes

运行systemctl start命令启动kubelet服务，并设置为开机启动：

systemctl start kubelet
systemctl enable kubelet

（2）在两台worker上，使用kubeadm join命令加入到集群

[root@k8s-node3 ~]# kubeadm join 192.168.56.201:6443 --token abcdef.0123456789abcdef \
>         --discovery-token-ca-cert-hash sha256:5d62fc27e71f83a104de94b73e3a77291056fb2cc483df6ebf7447440843e805
[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'
[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.

[root@k8s-node3 ~]# 

此时再次在master上查看node节点：

[root@k8s-node1 ~]# kubectl get nodes
NAME        STATUS     ROLES                  AGE     VERSION
k8s-node1   NotReady   control-plane,master   17m     v1.23.1
k8s-node2   NotReady   <none>                 2m15s   v1.23.1
k8s-node3   NotReady   <none>                 113s    v1.23.1
[root@k8s-node1 ~]#

现在三个节点，已经出现了，但是状态都是NotReady，这是因为我们还没有安装网络插件，网络插件有很多种，我们选择Calico CNI插件。

安装CNI网络插件

只需要在master设备上安装calico cni即可

[root@k8s-node1 ~]# kubectl apply -f "https://docs.projectcalico.org/manifests/calico.yaml"
configmap/calico-config created
customresourcedefinition.apiextensions.k8s.io/bgpconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/bgppeers.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/blockaffinities.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/caliconodestatuses.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/clusterinformations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/felixconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/globalnetworkpolicies.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/globalnetworksets.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/hostendpoints.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamblocks.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamconfigs.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamhandles.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ippools.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipreservations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/kubecontrollersconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/networkpolicies.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/networksets.crd.projectcalico.org created
clusterrole.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrole.rbac.authorization.k8s.io/calico-node created
clusterrolebinding.rbac.authorization.k8s.io/calico-node created
daemonset.apps/calico-node created
serviceaccount/calico-node created
deployment.apps/calico-kube-controllers created
serviceaccount/calico-kube-controllers created
Warning: policy/v1beta1 PodDisruptionBudget is deprecated in v1.21+, unavailable in v1.25+; use policy/v1 PodDisruptionBudget
poddisruptionbudget.policy/calico-kube-controllers created
[root@k8s-node1 ~]# 

在master上再次查看Node状态：

[root@k8s-node1 ~]# kubectl get nodes
NAME        STATUS   ROLES                  AGE   VERSION
k8s-node1   Ready    control-plane,master   28m   v1.23.1
k8s-node2   Ready    <none>                 13m   v1.23.1
k8s-node3   Ready    <none>                 12m   v1.23.1
[root@k8s-node1 ~]# 

至此，已经完成了kubeadm方式安装kubernetes。