文章转载自2019年11月20日，如果比较贴近这个时间，此文可以参考。

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
centos 7.6.1810	3.10.0-957.el7.x86_64	19.03.5	192.168.58.133	k8smaster
centos 7.6.1810	3.10.0-957.el7.x86_64	19.03.5	192.168.58.134	k8snode01

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

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

vi /etc/hostname

k8smaster

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=192.168.58.133 \
--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

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：

[root@k8smaster /root]$kubeadm init --kubernetes-version=1.16.3 --apiserver-advertise-address=192.168.58.133 --image-repository registry.aliyuncs.com/google_containe
rs --service-cidr=10.1.0.0/16 --pod-network-cidr=10.244.0.0/16
[init] Using Kubernetes version: v1.16.3
[preflight] Running pre-flight checks
        [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 19.03.5. Latest validated version: 18.09
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8smaster kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.1.0.1 192.168.58.133]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [k8smaster localhost] and IPs [192.168.58.133 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8smaster localhost] and IPs [192.168.58.133 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 18.503711 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.16" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node k8smaster as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node k8smaster as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: zqj4sl.5dlnxyew63pcc7lp
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[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

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 192.168.58.133:6443 --token zqj4sl.5dlnxyew63pcc7lp \
    --discovery-token-ca-cert-hash sha256:fcf730bb86251f0b086a3d43a0c1f6a35b632eee79f69e37554515a2d034d95d

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@k8smaster /root/Documents/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-6b64bcd855-29mx6   1/1     Running   0          81s   10.244.16.129    k8smaster   <none>           <none>
kube-system   calico-node-b7cc7                          1/1     Running   0          81s   192.168.58.133   k8smaster   <none>           <none>
kube-system   coredns-58cc8c89f4-95fc5                   1/1     Running   0          30m   10.244.16.131    k8smaster   <none>           <none>
kube-system   coredns-58cc8c89f4-cn2lc                   1/1     Running   0          30m   10.244.16.130    k8smaster   <none>           <none>
kube-system   etcd-k8smaster                             1/1     Running   0          30m   192.168.58.133   k8smaster   <none>           <none>
kube-system   kube-apiserver-k8smaster                   1/1     Running   0          30m   192.168.58.133   k8smaster   <none>           <none>
kube-system   kube-controller-manager-k8smaster          1/1     Running   0          30m   192.168.58.133   k8smaster   <none>           <none>
kube-system   kube-proxy-6l7kg                           1/1     Running   0          30m   192.168.58.133   k8smaster   <none>           <none>
kube-system   kube-scheduler-k8smaster                   1/1     Running   0          29m   192.168.58.133   k8smaster   <none>           <none>

确保 calico-kube-controllers ip地址是10.244.0.0/16 网段了。

设置开机启动

systemctl enable kubelet

五、node加入集群

修改主机名

vi /etc/hostname

k8snode01

加入节点

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

kubeadm join 192.168.58.133:6443 --token zqj4sl.5dlnxyew63pcc7lp \
    --discovery-token-ca-cert-hash sha256:fcf730bb86251f0b086a3d43a0c1f6a35b632eee79f69e37554515a2d034d95d

设置开机启动

systemctl enable kubelet

查看节点

登录到master，使用命令查看

[root@k8smaster /root/Documents/k8s]$kubectl get nodes -o wide
NAME        STATUS   ROLES    AGE   VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION          CONTAINER-RUNTIME
k8smaster   Ready    master   64m   v1.16.3   192.168.58.133   <none>        CentOS Linux 7 (Core)   3.10.0-957.el7.x86_64   docker://19.3.5
k8snode01   Ready    <none>   73s   v1.16.3   192.168.58.134   <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@k8smaster /root/Documents/k8s]$kubectl get pod,svc -o wide
NAME                         READY   STATUS    RESTARTS   AGE   IP              NODE        NOMINATED NODE   READINESS GATES
pod/nginx-86c57db685-28qkb   1/1     Running   0          37s   10.244.249.65   k8snode01   <none>           <none>

NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE   SELECTOR
service/kubernetes   ClusterIP   10.1.0.1       <none>        443/TCP        81m   <none>
service/nginx        NodePort    10.1.137.110   <none>        80:31339/TCP   31s   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://192.168.58.133:31339/

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://192.168.58.133:30005/

效果如下：

注意：使用node节点ip+nodeport也可以访问。

本文参考链接：
https://yq.aliyun.com/articles/626118
https://blog.csdn.net/fenglailea/article/details/88745642

Allen Leung

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CentOS7 安装 Kubernetes1.16.3 （文章转载自2019年11月20日）

文章转载自2019年11月20日，如果比较贴近这个时间，此文可以参考。

一、概述

系统环境

二、准备工作

关闭防火墙

禁用SELINUX

修改k8s.conf文件

关闭swap

安装docker

修改主机名

三、安装kubeadm，kubelet，kubectl

修改yum安装源

安装软件

四、初始化Master节点

运行初始化命令

配置kubectl工具

安装Calico

查看Pod状态

五、node加入集群

修改主机名

加入节点

查看节点

六、创建Pod

创建nginx

查看pod和svc

允许外网访问nodePort

测试访问

命令补全

七、使用yml发布应用

访问页面

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