K8S: （一）CentOS 单机部署初探

说明：K8S单机安装可能遇到很多坑，网上目前的大部分教程已经不适用最新版了。踩过坑后与大家分享一下方法

一、环境准备

安装VirtualBox:下载CentOS 7: http://mirrors.163.com/centos/7.7.1908/isos/x86_64/CentOS-7-x86_64-DVD-1908.torrent安装CentOS 7: 如果机器支持，建议选择图形界面方便使用修改软件源

wget -O /etc/yum.repos.d/CentOS- .repo http://mirrors.aliyun.com/repo/Centos-7.repo
yum makecache

二、安装k8s修改配置

安装k8s,etcd,docker

yum install -y etcd kubernetes

配置修改参考: https://lihaoquan.me/2017/2/25/create-kubernetes-single-node-mode.html

启动下列服务:

systemctl start etcd
systemctl start docker
systemctl start kube-apiserver.service
systemctl start kube-controller-manager.service
systemctl start kube-scheduler.service
systemctl start kubelet.service
systemctl start kube-proxy.service

如果遇到错误，则使用journalctl -xe查看错误信息，可能遇到需要设置防火墙，设置代理等问题

journalctl -xe

三、拉取启动镜像

安装mysql

docker pull mysql:5.7

创建文件： mysql-rc.yaml

apiVersion: v1
kind: ReplicationController
 data:
  name: mysql
spec:
  replicas: 1
  selector:
    app: mysql
  template:
     data:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        ports: 
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"

kubectl命令手册： https://hardocs.com/d/kubernetes/136-Command%20Reference.html

kubectl create -f mysql-rc.yaml

#使用mysql 5.7，直接pull mysql会拉到mysql 8版本，老的JDBC可能不兼容

查看mysql具体启动情况，也会包含错误信息

kubectl describe pod mysql

下载安装证书

wget [http://mirror.centos.org/centos/7/os/x86\_64/Packages/python-rhsm-certificates-1.19.10-1.el7\_4.x86\_64.rpm](http://mirror.centos.org/centos/7/os/x86_64/Packages/python-rhsm-certificates-1.19.10-1.el7_4.x86_64.rpm)
rpm2cpio python-rhsm-certificates-1.19.10-1.el7\_4.x86\_64.rpm | cpio -iv --to-stdout ./etc/rhsm/ca/redhat-uep.pem | tee /etc/rhsm/ca/redhat-uep.pem
#rpm2cpio命令用于将rpm软件包转换为cpio格式的文件，cpio命令主要是用来建立或者还原备份档的工具程序，cpio命令可以复制文件到归档包中，或者从归档包中复制文件。

删除并重新生成mysql的rc

kubectl delete -f mysql-rc.yaml

kubectl get pods

kubectl create -f mysql-rc.yaml

kubectl describe pod mysql

kubectl get pods

创建文件：mysql-svc.yaml

apiVersion: v1
kind: Service
 data: 
  name: mysql
spec:
  ports:
    - port: 3306
  selector:
    app: mysql

kubectl create -f mysql-svc.yaml

拉取并运行tomcat的demo镜像

docker pull kubeguide/tomcat-app:v1

创建文件:myweb-rc.yaml

apiVersion: v1
kind: ReplicationController
 data:
  name: myweb
spec:
  replicas: 5
  selector:
    app: myweb
  template:
     data:
      labels:
        app: myweb
    spec:
      containers:
      - name: myweb
        image: docker.io/kubeguide/tomcat-app:v1
        ports: 
        - containerPort: 8080
        env:
        - name: MYSQL_SERVICE_HOST
          value: "10.254.65.209"    #<===这里的mysql地址需要填写service的mysql地址，执行kubectl get svc 查看
        - name: MYSQL_SERVICE_PORT
          value: "3306"

创建文件：myweb-svc.yaml

apiVersion: v1
kind: Service
 data: 
  name: myweb
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 30001   #外部端口映射
  selector:
    app: myweb

kubectl create -f myweb-rc.yaml
kubectl create -f myweb-svc.yaml

四、外部访问与查看数据

访问:http://127.0.0.1:30001/demo/index.jsp 进行操作

可以进入容器查看mysql中已经有数据了