Kubernetes 是一个自动化的容器编排平台，它负责应用的部署、应用的弹性以及应用的管理，本文介绍使用kubeadm搭建 K8S 集群。
环境准备 #
主机配置 #
| 主机名 | IP地址 | 操作系统 | 配置 |
|---|---|---|---|
| Master | 10.10.10.60 | CentOS7.9 | 2CPU 2G内存 20G硬盘 |
| Node1 | 10.10.10.61 | CentOS7.9 | 2CPU 2G内存 20G硬盘 |
| Node2 | 10.10.10.62 | CentOS7.9 | 2CPU 2G内存 20G硬盘 |
自行安装Docker
以下环境配置需在三台主机都要执行
- 关闭selinux
setenforce 0
sed -i "s/SELINUX=enforcing/SELINUX=disabled/g" /etc/selinux/config
- 关闭swap分区或禁用swap文件
$ swapoff -a
$ sed -ri 's/.*swap.*/#&/' /etc/fstab # 永久
- 关闭防火墙
[root@master ~]# systemctl stop firewalld
[root@master ~]# systemctl disable firewalld
- 修改内核参数
$ vim /etc/sysctl.conf
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
$ sysctl -p
- 启用内核模块
$ vim /etc/sysconfig/modules/ipvs.modules
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
- 配置hosts
$ vim /etc/hosts
10.10.10.60 master
10.10.10.61 node1
10.10.10.62 node2
- 配置时间同步
# 时间同步
[xdl@k8s-master] ~$ sudo vim /etc/chrony.conf
server ntp.aliyun.com iburst
[xdl@k8s-master] ~$ sudo systemctl restart chronyd.service
重启系统
安装K8S #
- 配置Kubernets 的yum源
$ vim /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
- 安装kubelet、kubeadm、kubectl[v1.21.2]
$ yum install -y kubelet kubeadm kubectl
# 指定版本
$ yum install -y kubelet-1.20.0 kubeadm-1.20.0 kubectl-1.20.0
- 启动kubelet服务
$ sudo systemctl enable kubelet
$ sudo systemctl start kubelet
设置Docker #
- 修改Docker配置文件
[xdl@k8s-master] ~$ vim /etc/docker/daemon.json
{
"registry-mirrors": [
"https://xxxxxxx.mirror.aliyuncs.com"
],
"insecure-registries": [],
"exec-opts": ["native.cgroupdriver=systemd"]
}
[xdl@k8s-master] ~$ sudo systemctl restart docker.service
kubernetes集群初始化 #
Master节点创建集群（该操作只在master主机执行）
$ sudo kubeadm init \
--kubernetes-version=v1.21.2 \
--image-repository registry.aliyuncs.com/google_containers \
--pod-network-cidr=10.244.0.0/16 \
--service-cidr=10.96.0.0/12 \
--apiserver-advertise-address=10.10.10.60
由于默认拉取镜像地址k8s.gcr.io国内无法访问，这里指定阿里云镜像仓库地址。
如果失败，使用
kubeadm reset重置
[xdl@k8s-master] ~$ mkdir -p $HOME/.kube
[xdl@k8s-master] ~$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[xdl@k8s-master] ~$ sudo chown $(id -u):$(id -g) $HOME/.kube/config
node节点加入集群
# node1
[xdl@k8s-node1] ~$ sudo kubeadm join 10.10.10.60:6443 --token tzbczr.r1lmokzaxfnirp73 \
--discovery-token-ca-cert-hash sha256:b9e7a95e7ac84f97c2486ff850b9891c61c32d35d57a8248401f62b97660ea2e
# node2
[xdl@k8s-node2] ~$ sudo kubeadm join 10.10.10.60:6443 --token tzbczr.r1lmokzaxfnirp73 \
--discovery-token-ca-cert-hash sha256:b9e7a95e7ac84f97c2486ff850b9891c61c32d35d57a8248401f62b97660ea2e
master节点查看node节点信息
[xdl@k8s-master] ~$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master Ready control-plane,master 61m v1.21.2
k8s-node1 Ready <none> 47m v1.21.2
k8s-node2 Ready <none> 46m v1.21.2
kubernetes安装CNI网络插件 #
kubernetes支持多种网络插件，如：flannel、calico、canal等，任选一种使用即可，本实验选择flannel
只在master节点安装flannel插件即可，该插件使用的是DaemonSet控制器，该控制器会在每个节点上都运行
#获取flannel配置文件
[root@master ~]# wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
#执行文件启动flannel
[root@master ~]# kubectl apply -f kube-flannel.yml
等待几分钟，查看状态
[xdl@k8s-master] ~$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-558bd4d5db-kzvhc 1/1 Running 0 63m
kube-system coredns-558bd4d5db-p7x9t 1/1 Running 0 63m
kube-system etcd-k8s-master 1/1 Running 0 63m
kube-system kube-apiserver-k8s-master 1/1 Running 0 64m
kube-system kube-controller-manager-k8s-master 1/1 Running 0 64m
kube-system kube-flannel-ds-pfll6 1/1 Running 0 49m
kube-system kube-flannel-ds-xfvsn 1/1 Running 0 50m
kube-system kube-flannel-ds-xvsst 1/1 Running 0 52m
kube-system kube-proxy-9zjlz 1/1 Running 0 50m
kube-system kube-proxy-nj8lm 1/1 Running 0 49m
kube-system kube-proxy-sqfkx 1/1 Running 0 63m
kube-system kube-scheduler-k8s-master 1/1 Running 0 63m
全部显示running则说明搭建成功了。
测试Kubernets 集群 #
在Kubernetes集群中创建一个pod，验证是否正常运行：
[xdl@k8s-master] ~$ kubectl create deployment nginx --image=nginx
deployment.apps/nginx created
[xdl@k8s-master] ~$ kubectl expose deployment nginx --port=80 --type=NodePort
service/nginx exposed
[xdl@k8s-master] ~$ kubectl get pods,svc
NAME READY STATUS RESTARTS AGE
pod/nginx-6799fc88d8-5982c 1/1 Running 0 73s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14h
service/nginx NodePort 10.104.158.32 <none> 80:32389/TCP 20s
# 测试
[xdl@k8s-master] ~$ curl -I node1:32389
HTTP/1.1 200 OK
Server: nginx/1.21.1