Kubernetes Part1 Kubeadmin 快速部署 1.19 版本

1. 为什么需要K8S

2. K8S 是什么

3. 安装 K8S

本文通过kubeadmin进行安装最新版本的1.19 K8S 版本，因为简单易上手。（操作系统选择了Centos 7.6）

3.1 前提条件

3台虚拟机准备 2vCPU 4G内存以上需要联网拉去镜像
配置DNS解析记录（没有DNS服务器需要在每台服务器上添加Host主机记录

3.2 环境准备

名称	IP 地址
K8S-Master	172.16.0.11
K8S-Node01	172.16.0.21
K8S-Node02	172.16.0.22

3.3 安装步骤

3.3.1 系统初始化（所有节点操作）

关闭防火墙：
$ systemctl stop firewalld
$ systemctl disable firewalld

关闭selinux：
$ sed -i 's/enforcing/disabled/' /etc/selinux/config  # 永久
$ setenforce 0  # 临时

关闭swap：
$ swapoff -a  # 临时
$ vim /etc/fstab  # 永久

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
$ sysctl --system  # 生效

时间同步：
$ yum install ntpdate -y
$ ntpdate ntp.aliyun.com

3.3.2 安装 Docker（所有节点）

#安装 Docker Repo
$ wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo

# 安装Docker
$ yum -y install docker-ce

# 重启服务
$ systemctl enable docker && systemctl start docker

# 配置Docker 镜像加速器 使用阿里云镜像仓库 代替Docker Hub 
$ cat > /etc/docker/daemon.json << EOF
{
  "registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"]
}
EOF

$ systemctl restart docker

3.3.3 安装K8S

### 所有节点操作

# 下载K8S REPO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=0
repo_gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

# 固定kubelet 版本
$ yum install -y kubelet-1.19.0 kubeadm-1.19.0 kubectl-1.19.0
$ systemctl enable kubelet

# Master节点操作
$ kubeadm init \
  --apiserver-advertise-address=172.16.0.11 \
  --image-repository registry.aliyuncs.com/google_containers \
  --kubernetes-version v1.19.0 \
  --service-cidr=10.96.0.0/12 \
  --pod-network-cidr=10.244.0.0/16 \
  --ignore-preflight-errors=all

# 输出如下

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

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 172.16.0.11:6443 --token lgvmn2.cfyk6dky82dr7z8c \
--discovery-token-ca-cert-hash sha256:759802868be91149d9c246a6f0cf5235c09d7ab9a9cef143f490fbc1b657e4de

### 查看节点

[root@k8s-master01 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
k8s-master01 NotReady master 4m56s v1.19.0

--apiserver-advertise-address 集群通告地址
--image-repository 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
--kubernetes-version K8s版本，与上面安装的一致
--service-cidr 集群内部虚拟网络，Pod统一访问入口
--pod-network-cidr Pod网络，，与下面部署的CNI网络组件yaml中保持一致

# Master 节点操作
### 使用配置文件部署
$ vi kubeadm.conf
apiVersion: kubeadm.k8s.io/v1beta2
kind: ClusterConfiguration
kubernetesVersion: v1.19.0
imageRepository: registry.aliyuncs.com/google_containers 
networking:
  podSubnet: 10.244.0.0/16 
  serviceSubnet: 10.96.0.0/12 

$ kubeadm init --config kubeadm.conf --ignore-preflight-errors=all

# Master节点操作

#### 拷贝K8S 认证文件到默认路径
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# NODE01 和 NODE02节点上操作
kubeadm join 172.16.0.11:6443 --token lgvmn2.cfyk6dky82dr7z8c \
    --discovery-token-ca-cert-hash sha256:759802868be91149d9c246a6f0cf5235c09d7ab9a9cef143f490fbc1b657e4de 

# 运行完成后 在Master节点上查看节点状态
[root@k8s-master01 ~]# kubectl get node
NAME           STATUS     ROLES    AGE     VERSION
k8s-master01   NotReady   master   7m28s   v1.19.0
k8s-node01     NotReady   <none>   21s     v1.19.0
k8s-node02     NotReady   <none>   6s      v1.19.0

　　部署 CNI 网络插件

# Master节点上操作
wget https://docs.projectcalico.org/manifests/calico.yaml
下载完后还需要修改里面定义Pod网络（CALICO_IPV4POOL_CIDR），与前面kubeadm init指定的一样(10.244.0.0/16)
~~~~~ 注意对其


# 应用配置
kubectl apply -f calico.yaml

# 查看POD状态
kubectl get pods -n kube-system

[root@k8s-master01 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
k8s-master01 Ready master 35m v1.19.0
k8s-node01 Ready <none> 27m v1.19.0
k8s-node02 Ready <none> 27m v1.19.0

3.4 测试群集　

# 创建无状态应用
$ kubectl create deployment nginx --image=nginx
[root@k8s-master01 ~]# kubectl get pod
NAME                     READY   STATUS    RESTARTS   AGE
nginx-6799fc88d8-snz4j   1/1     Running   0          45s

#暴露80端口 svc类型为 Nodeport
$ kubectl expose deployment nginx --port=80 --type=NodePort
[root@k8s-master01 ~]# kubectl get svc
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.96.0.1     <none>        443/TCP        40m
nginx        NodePort    10.99.4.209   <none>        80:30027/TCP   5s

　验证

[root@k8s-master01 ~]# curl http://172.16.0.21:30027
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
         35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

3.5 完成

命令补全：

k8s 命令自动补全 
yum install -y bash-completion
source /usr/share/bash-completion/bash_completion
source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc

MAC上：

$ brew install bash-completion
$ source $(brew --prefix)/etc/bash_completion
$ source <(kubectl completion bash)