CentOS7安装Kubernetes1.16.3

一、概述

手工搭建 Kubernetes 集群是一件很繁琐的事情，为了简化这些操作，就产生了很多安装配置工具，如 Kubeadm ，Kubespray，RKE 等组件，我最终选择了官方的 Kubeadm 主要是不同的 Kubernetes 版本都有一些差异，Kubeadm 更新与支持的会好一些。Kubeadm 是 Kubernetes 官方提供的快速安装和初始化 Kubernetes 集群的工具，目前的还处于孵化开发状态，跟随 Kubernetes 每个新版本的发布都会同步更新, 强烈建议先看下官方的文档了解下各个组件与对象的作用。

https://kubernetes.io/docs/concepts/
https://kubernetes.io/docs/setup/independent/install-kubeadm/
https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm/

系统环境

系统	内核	docker	ip	主机名	配置
centos 7.6	3.10.0-957.el7.x86_64	19.03.5	192.168.31.150	k8s-master	2核4G
centos 7.6	3.10.0-957.el7.x86_64	19.03.5	192.168.31.183	k8s-node01	2核4G

注意：请确保CPU至少2核，内存2G

二、准备工作

关闭防火墙

如果各个主机启用了防火墙，需要开放Kubernetes各个组件所需要的端口，可以查看Installing kubeadm中的”Check required ports”一节。这里简单起见在各节点禁用防火墙：

systemctl stop firewalld
systemctl disable firewalld

禁用SELINUX

# 临时禁用
setenforce 0
# 永久禁用 
vim /etc/selinux/config    # 或者修改/etc/sysconfig/selinux
SELINUX=disabled

修改k8s.conf文件

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

开启ipv4转发

vi /etc/sysctl.conf

内容如下：

net.ipv4.ip_forward = 1

刷新参数

sysctl -p

关闭swap

# 临时关闭
swapoff -a

修改 /etc/fstab 文件，注释掉 SWAP 的自动挂载（永久关闭swap，重启后生效）

# 注释掉以下字段
/dev/mapper/cl-swap     swap                    swap    defaults        0 0

安装docker

这里就不再叙述了，请参考链接：

https://www.cnblogs.com/xiao987334176/p/11771657.html

修改主机名

hostnamectl set-hostname k8s-master

注意：主机名不能带下划线，只能带中划线
否则安装k8s会报错

could not convert cfg to an internal cfg: nodeRegistration.name: Invalid value: "k8s_master": a DNS-1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')

三、安装kubeadm，kubelet，kubectl

在各节点安装kubeadm，kubelet，kubectl

修改yum安装源

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

安装软件

目前最新版本是：1.16.3

yum install -y kubelet-1.16.3-0 kubeadm-1.16.3-0 kubectl-1.16.3-0
systemctl enable kubelet && systemctl start kubelet

以上，就是master和node都需要操作的部分。

四、初始化Master节点

运行初始化命令

kubeadm init --kubernetes-version=1.16.3 \
--apiserver-advertise-address=192.168.31.150 \
--image-repository registry.aliyuncs.com/google_containers \
--service-cidr=10.1.0.0/16 \
--pod-network-cidr=10.244.0.0/16

参数解释：

–kubernetes-version: 用于指定k8s版本；
–apiserver-advertise-address：用于指定kube-apiserver监听的ip地址,就是 master本机IP地址。
–pod-network-cidr：用于指定Pod的网络范围； 10.244.0.0/16
–service-cidr：用于指定SVC的网络范围；
–image-repository: 指定阿里云镜像仓库地址

注意：修改–apiserver-advertise-address为你自己的环境的master ip

这一步很关键，由于kubeadm 默认从官网k8s.grc.io下载所需镜像，国内无法访问，因此需要通过–image-repository指定阿里云镜像仓库地址

集群初始化成功后返回如下信息：
记录生成的最后部分内容，此内容需要在其它节点加入Kubernetes集群时执行。
输出如下：

...
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
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 192.168.31.150:6443 --token ute1qr.ylhan3tn3eohip20 \
    --discovery-token-ca-cert-hash sha256:f7b37ecd602deb59e0ddc2a0cfa842f8c3950690f43a5d552a7cefef37d1fa31

配置kubectl工具

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

安装Calico

mkdir k8s
cd k8s
wget https://docs.projectcalico.org/v3.10/getting-started/kubernetes/installation/hosted/kubernetes-datastore/calico-networking/1.7/calico.yaml

## 将192.168.0.0/16修改ip地址为10.244.0.0/16
sed -i 's/192.168.0.0/10.244.0.0/g' calico.yaml

加载Calico

kubectl apply -f calico.yaml

查看Pod状态

等待几分钟，确保所有的Pod都处于Running状态

[root@k8s_master k8s]# kubectl get pod --all-namespaces -o wide
NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE     IP                NODE         NOMINATED NODE   READINESS GATES
kube-system   calico-kube-controllers-6b64bcd855-tdv2h   1/1     Running   0          2m37s   192.168.235.195   k8s-master   <none>           <none>
kube-system   calico-node-4xgk8                          1/1     Running   0          2m38s   192.168.31.150    k8s-master   <none>           <none>
kube-system   coredns-58cc8c89f4-8672x                   1/1     Running   0          45m     192.168.235.194   k8s-master   <none>           <none>
kube-system   coredns-58cc8c89f4-8h8tq                   1/1     Running   0          45m     192.168.235.193   k8s-master   <none>           <none>
kube-system   etcd-k8s-master                            1/1     Running   0          44m     192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-apiserver-k8s-master                  1/1     Running   0          44m     192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-controller-manager-k8s-master         1/1     Running   0          44m     192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-proxy-6f42j                           1/1     Running   0          45m     192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-scheduler-k8s-master                  1/1     Running   0          44m     192.168.31.150    k8s-master   <none>           <none>

注意：calico-kube-controllers容器的网段不是10.244.0.0/16

删除Calico，重新加载

kubectl delete -f calico.yaml
kubectl apply -f calico.yaml

再次查看ip

[root@k8s-master k8s]# kubectl get pod --all-namespaces -o wide
NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE     IP                NODE         NOMINATED NODE   READINESS GATES
kube-system   calico-kube-controllers-6b64bcd855-qn6bs   0/1     Running   0          18s     10.244.235.193    k8s-master   <none>           <none>
kube-system   calico-node-cdnvz                          1/1     Running   0          18s     192.168.31.150    k8s-master   <none>           <none>
kube-system   coredns-58cc8c89f4-8672x                   1/1     Running   1          5h22m   192.168.235.197   k8s-master   <none>           <none>
kube-system   coredns-58cc8c89f4-8h8tq                   1/1     Running   1          5h22m   192.168.235.196   k8s-master   <none>           <none>
kube-system   etcd-k8s-master                            1/1     Running   1          5h22m   192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-apiserver-k8s-master                  1/1     Running   1          5h21m   192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-controller-manager-k8s-master         1/1     Running   1          5h22m   192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-proxy-6f42j                           1/1     Running   1          5h22m   192.168.31.150    k8s-master   <none>           <none>
kube-system   kube-scheduler-k8s-master                  1/1     Running   1          5h21m   192.168.31.150    k8s-master   <none>           <none>

发现，ip地址已经是10.244.0.0/16 网段了。

设置开机启动

systemctl enable kubelet

五、node加入集群

准备工作

请查看上文中的准备工作，确保都执行了！！！

修改主机名部分，改为k8s-node01

hostnamectl set-hostname k8s-node01

加入节点

登录到node节点，确保已经安装了docker和kubeadm，kubelet，kubectl

kubeadm join 192.168.31.150:6443 --token ute1qr.ylhan3tn3eohip20 \
    --discovery-token-ca-cert-hash sha256:f7b37ecd602deb59e0ddc2a0cfa842f8c3950690f43a5d552a7cefef37d1fa31

设置开机启动

systemctl enable kubelet

查看节点

登录到master，使用命令查看

[root@k8s_master k8s]# kubectl get nodes -o wide
NAME         STATUS   ROLES    AGE     VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION          CONTAINER-RUNTIME
k8s-master   Ready    master   87m     v1.16.3   192.168.31.150   <none>        CentOS Linux 7 (Core)   3.10.0-957.el7.x86_64   docker://19.3.5
k8s-node01   Ready    <none>   5m14s   v1.16.3   192.168.31.183   <none>        CentOS Linux 7 (Core)   3.10.0-957.el7.x86_64   docker://19.3.5

六、创建Pod

创建nginx

kubectl create deployment nginx --image=nginx
kubectl expose deployment nginx --port=80 --type=NodePort

查看pod和svc

[root@k8s-master k8s]# kubectl get pod,svc -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP              NODE         NOMINATED NODE   READINESS GATES
pod/nginx-86c57db685-z2kdd   1/1     Running   0          18m   10.244.85.194   k8s-node01   <none>           <none>

NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE    SELECTOR
service/kubernetes   ClusterIP   10.1.0.1       <none>        443/TCP        111m   <none>
service/nginx        NodePort    10.1.111.179   <none>        80:30876/TCP   24m    app=nginx

允许外网访问nodePort

iptables -P FORWARD ACCEPT

测试访问

使用master ip+nodeport端口方式访问

http://192.168.31.150:30876/

效果如下：

命令补全

（仅master）

yum install -y bash-completion

source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc
source  ~/.bashrc

必须退出一次，再次登录，就可以了

七、使用yml发布应用

以flaskapp为例子

flaskapp-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: flaskapp-1
spec:
  selector:
    matchLabels:
      run: flaskapp-1
  replicas: 1
  template:
    metadata:
      labels:
        run: flaskapp-1
    spec:
      containers:
      - name: flaskapp-1
        image: jcdemo/flaskapp
        ports:
        - containerPort: 5000

flaskapp-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: flaskapp-1
  labels:
    run: flaskapp-1
spec:
  type: NodePort
  ports:
  - port: 5000
    name: flaskapp-port
    targetPort: 5000
    protocol: TCP
    nodePort: 30005
  selector:
    run: flaskapp-1

加载yml文件

kubectl apply -f flaskapp-service.yaml 
kubectl apply -f flaskapp-deployment.yaml

访问页面

使用master ip+nodeport访问

http://192.168.31.183:30005/