---

前言

在Centos7下安装k8s集群，安装的版本是 1.20.2

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一、环境准备

1、集群节点

准备两台机器

ip	hostname	节点
172.16.10.158	k8s-master	master节点
172.16.10.159	k8s-node01	node01节点

2、设置hostname

master节点上执行

hostnamectl set-hostname k8s-master

node节点上执行

hostnamectl set-hostname k8s-node01

然后把所有主机加入/etc/hosts文件，所有机器都执行

echo "172.16.10.158 k8s-master" >> /etc/hosts
echo "172.16.10.159 k8s-node01" >> /etc/hosts

3、关闭防火墙

systemctl stop firewalld
systemctl disable firewalld

4、关闭selinux

setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

5、关闭swap

swapoff -a

永久关闭，打开/etc/fstab，注释掉

#/dev/mapper/centos-swap swap                    swap    defaults        0 0

6、配置系统内核参数

cat > /etc/sysctl.d/k8s.conf <<EOF
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
vm.swappiness                       = 0
EOF

执行命令使得配置生效

sysctl -p /etc/sysctl.d/k8s.conf

7、设置FORWARD规则为ACCEPT

iptables -P FORWARD ACCEPT

开机自启

cat > /usr/lib/systemd/system/forward-accept.service <<EOF
[Unit]
Description=set forward accept
After=docker.service
 
[Service]
ExecStart=/usr/sbin/iptables -P FORWARD ACCEPT
 
[Install]
WantedBy=multi-user.target
EOF

systemctl enable forward-accept && systemctl start forward-accept

二、安装步骤

1、安装docker

参考 docker学习(一)安装

2、安装k8s组件

安装组件 kubelet、kubeadm、kubectl

（1）配置yum源

cat > /etc/yum.repos.d/kubernetes.repo <<EOF
[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

（2）安装

yum install -y kubelet-1.20.2-0.x86_64 kubeadm-1.20.2-0.x86_64 kubectl-1.20.2-0.x86_64

（3）开机自启

systemctl enable kubelet
systemctl start kubelet

3、配置daemon.json

配置镜像拉取地址

cat << EOF > /etc/docker/daemon.json

{
  "exec-opts": ["native.cgroupdriver= cgroupfs"],
  "insecure-registries":["172.16.10.158:80", "quay.io", "k8s.gcr.io", "gcr.io"]
}
EOF

重启docker

systemctl daemon-reload
systemctl restart docker

4、安装master节点

（1）设置cgroup-driver=cgroupfs

各机器都执行

sed -i 's!Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"!Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --cgroup-driver=cgroupfs"!g' /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf

（2）在master节点上初始化master

如果下载镜像较慢，则可以将镜像提前打包到本地镜像仓库中。

kubeadm init --kubernetes-version=v1.20.2 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --apiserver-advertise-address=172.16.10.158 --ignore-preflight-errors=Swap --ignore-preflight-errors=NumCPU

执行成功，会输出

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 172.16.10.158:6443 --token nw86ui.sbqzw77nflspgfb2 \
    --discovery-token-ca-cert-hash sha256:598b7f5d72443cbef9fedac57c2b4ef59f06dc719f9f634b23e662270830438c 

（3）让用户使用kubelet

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

5、安装node

执行安装master时打印的token

[root@k8s-node01 scripts]#kubeadm join 172.16.10.158:6443 --token nw86ui.sbqzw77nflspgfb2 \
    --discovery-token-ca-cert-hash sha256:598b7f5d72443cbef9fedac57c2b4ef59f06dc719f9f634b23e662270830438c 
[preflight] Running pre-flight checks
	[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[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.

查看集群

[root@k8s-master k8s]# kubectl get nodes
NAME         STATUS     ROLES                  AGE     VERSION
k8s-master   NotReady   control-plane,master   5m26s   v1.20.2
k8s-node01   NotReady   <none>                 106s    v1.20.2

6、安装网络组件calio

下载calico.yaml，在该文件目录执行

kubectl apply -f calico.yaml

7、安装完后，等待pod都执行成功

[root@k8s-master calico]# kubectl get pods -n kube-system
NAME                                       READY   STATUS    RESTARTS   AGE
calico-kube-controllers-7fcc594497-9mzrr   1/1     Running   0          45s
calico-node-92sl4                          1/1     Running   0          45s
calico-node-nhvkp                          1/1     Running   0          45s
coredns-74ff55c5b-85vhs                    1/1     Running   0          9m22s
coredns-74ff55c5b-gw9sp                    1/1     Running   0          9m22s
etcd-k8s-master                            1/1     Running   0          9m27s
kube-apiserver-k8s-master                  1/1     Running   0          9m27s
kube-controller-manager-k8s-master         1/1     Running   0          9m27s
kube-proxy-cm9j4                           1/1     Running   0          5m59s
kube-proxy-t9z7p                           1/1     Running   0          9m22s
kube-scheduler-k8s-master                  1/1     Running   0          9m27s

[root@k8s-master calico]# kubectl get nodes
NAME         STATUS   ROLES                  AGE     VERSION
k8s-master   Ready    control-plane,master   9m42s   v1.20.2
k8s-node01   Ready    <none>                 6m2s    v1.20.2

可以看出，节点都处于Ready状态。