CentOS 7.9 环境下搭建k8s集群（一主两从）

一、硬件准备（虚拟主机）

角色	主机名	ip地址
master	k8s-master	172.16.36.198
node	k8s-node1	172.16.36.199
node	k8s-node2	172.16.36.200

CentOS Linux release 7.9.2009 (Core)
4核CPU、16G内存
使用命令hostnamectl set-hostname临时修改主机名

二、环境准备

• 1. 所有机器关闭防火墙

systemctl stop firewalld	#关闭
systemctl disable firewalld		#开机不自启
systemctl status firewalld		#查看状态

• 2. 所有机器关闭selinux

sed -i 's/enforcing/disabled/' /etc/selinux/config 
setenforce 0

• 3. 所有机器关闭swap

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

• 4. 所有机器上添加主机名与ip的对应关系

vim /etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
172.16.36.198 k8s-master
172.16.36.199 k8s-node1
172.16.36.200 k8s-node2

• 5. 在所有主机上将桥接的ipv4流量传递到iptables的链

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

三、为所有节点安装docker

yum install wget  -y
rm -rf /etc/yum.repos.d/*
wget -O /etc/yum.repos.d/centos7.repo http://mirrors.aliyun.com/repo/Centos-7.repo
wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo
wget -O /etc/yum.repos.d/docker-ce.repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
yum install docker-ce-20.10.11 -y
systemctl start docker
systemctl enable docker

#docker配置aliyun加速器
https://www.cnblogs.com/qddbky/p/18305018

四、集群部署

• 1. 为所有节点修改仓库，安装kubeadm、kubelet、kubectl

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
yum install kubelet-1.22.2 kubeadm-1.22.2 kubectl-1.22.2 -y
systemctl enable kubelet && systemctl start kubelet

• 2. 修改docker的配置（所有节点）

[root@k8s-master ~]# cat > /etc/docker/daemon.json <<EOF
{
  "registry-mirrors": ["https://jfn3yf7d.mirror.aliyuncs.com"],
  "exec-opts": ["native.cgroupdriver=systemd"]
}
EOF

systemctl daemon-reload
systemctl restart docker.service

这里从节点的kubelet.service状态报code=exited, status=1/FAILURE是正常的

• 3. 部署master节点（主节点k8s-master）

kubeadm init \
--apiserver-advertise-address=172.16.36.198 \
--image-repository registry.aliyuncs.com/google_containers \
--kubernetes-version v1.22.2 \
--control-plane-endpoint k8s-master \
--service-cidr=192.168.0.0/16 \
--pod-network-cidr=10.244.0.0/16

记得保存好这段命令是用于将一个工作节点（worker node）加入到已存在的 Kubernetes 集群中的过程。

[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/

You can now join any number of control-plane nodes by copying certificate authorities
and service account keys on each node and then running the following as root:

  kubeadm join k8s-master:6443 --token tmtcli.u0ycx3hwoa52nxh5 \
	--discovery-token-ca-cert-hash sha256:7d12f19434bba1e0e4e469284e4feeec5f69d2677c0ac471580f312f11e40d19 \
	--control-plane 

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

kubeadm join k8s-master:6443 --token tmtcli.u0ycx3hwoa52nxh5 \
	--discovery-token-ca-cert-hash sha256:7d12f19434bba1e0e4e469284e4feeec5f69d2677c0ac471580f312f11e40d19 

• (1)、遇到报错：

[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
	[ERROR Port-6443]: Port 6443 is in use
	[ERROR Port-10259]: Port 10259 is in use
	[ERROR Port-10257]: Port 10257 is in use
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-apiserver.yaml]: /etc/kubernetes/manifests/kube-apiserver.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-controller-manager.yaml]: /etc/kubernetes/manifests/kube-controller-manager.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-kube-scheduler.yaml]: /etc/kubernetes/manifests/kube-scheduler.yaml already exists
	[ERROR FileAvailable--etc-kubernetes-manifests-etcd.yaml]: /etc/kubernetes/manifests/etcd.yaml already exists
	[ERROR Port-10250]: Port 10250 is in use
	[ERROR Port-2379]: Port 2379 is in use
	[ERROR Port-2380]: Port 2380 is in use
	[ERROR DirAvailable--var-lib-etcd]: /var/lib/etcd is not empty
[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

• (2)、 解决办法：

kubeadm reset
# 然后重新初始化

• 4. 按照指示执行：

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

• 5. 查看kubelet.service状态

systemctl status kubelet.service

• 6. 安装网络插件flannel

官方文档：https://github.com/flannel-io/flannel

# 最好手动提前拉取所需镜像
docker pull quay.io/coreos/flannel:v0.14.0
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubectl apply -f kube-flannel.yml 

• 7. node节点向master节点注册

kubeadm join k8s-master:6443 --token tmtcli.u0ycx3hwoa52nxh5 \
	--discovery-token-ca-cert-hash sha256:7d12f19434bba1e0e4e469284e4feeec5f69d2677c0ac471580f312f11e40d19