linux(centos8):kubeadm单机安装kubernetes（kubernetes 1.18.3）

一，kubernetes安装的准备工作:

1，准备工作的各步骤请参见:

https://www.cnblogs.com/architectforest/p/13141743.html

 

2,  master节点默认不承担node角色的工作，

     我们这里为了在单机上做测试，允许master节点也运行pod

     ip：192.168.219.130

     hostname:kubemaster,

     hostname和ip的对应也加入到了/etc/hosts

 

说明：刘宏缔的架构森林是一个专注架构的博客，地址：https://www.cnblogs.com/architectforest

         对应的源码可以访问这里获取： https://github.com/liuhongdi/

说明：作者:刘宏缔 邮箱: 371125307@qq.com

 

二，在kubemaster这台server上安装kubernetes的kubelet/kubectl/kubeadm 

1,新建kubernetes的repo

[root@kubemaster ~]# vi /etc/yum.repos.d/kubernetes.repo

内容:

[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

2,安装kube三大件:(当前版本均为:1.18.3)

说明：三大件的作用:

kubelet：是systemd管理的一个daemon，负责启动pod和容器，
它是k8s中唯一在宿主机中启动的后台进程；

kubeadm: 负责安装初始化集群，部署完成之后不会再使用

kubectl: k8s的命令行工具，是管理k8s使用的主要工具
             用于管理pod/service

安装:

[root@kubemaster ~]# dnf install kubectl kubelet kubeadm

说明：如果提示是否确定导入 GPG 公钥，

输入y后回车即可 

 

3,查看安装后的效果：查看版本:

[root@kubemaster ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.3", GitCommit:"2e7996e3e2712684bc73f0dec0200d64eec7fe40", 
GitTreeState:"clean", BuildDate:"2020-05-20T12:52:00Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
The connection to the server localhost:8080 was refused - did you specify the right host or port?

[root@kubemaster ~]# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.3", GitCommit:"2e7996e3e2712684bc73f0dec0200d64eec7fe40",
 GitTreeState:"clean", BuildDate:"2020-05-20T12:49:29Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}

[root@kubemaster ~]# kubelet --version
Kubernetes v1.18.3

4,把kubelet配置为自启动

[root@centos8 ~]# systemctl enable kubelet.service 
Created symlink /etc/systemd/system/multi-user.target.wants/kubelet.service → /usr/lib/systemd/system/kubelet.service.
[root@kubemaster ~]# systemctl is-enabled kubelet.service
enabled

三，kubeadm 初始化kubenetes

1,执行初始化:

#--apiserver-advertise-address:   apiserver的地址：使用本机的ip

#--image-repository:kubeadm 默认从官网k8s.grc.io下载所需镜像，需要翻墙才能访问，所以用–image-repository指定阿里云镜像仓库地址

[root@kubemaster ~]# kubeadm init --kubernetes-version=1.18.3 --apiserver-advertise-address=192.168.219.130 
--image-repository registry.aliyuncs.com/google_containers  

说明：此过程要下需下载kubenetes所需容器的镜像，

           速度稍慢，需要等待

         如果另开一个终端执行ps,可以看到的它的子进程正在执行docker pull

[root@kubemaster ~]# ps auxfww
...
root  1530  0.0  0.2 152904 10540 ?        Ss   13:41   0:00  \_ sshd: root [priv]
root  1666  0.0  0.1 152904  5392 ?        S    13:41   0:00  |   \_ sshd: root@pts/0
root  1673  0.0  0.1  25588  3980 pts/0    Ss   13:41   0:00  |       \_ -bash
root  8076  0.0  0.8 142068 32836 pts/0    Sl+  14:22   0:00  |           \_ kubeadm init --kubernetes-version=1.18.3 --apiserver-advertise-address=192.168.219.130 --image-repository registry.aliyuncs.com/google_containers
root  8450  0.3  1.6 711476 63136 pts/0    Sl+  14:24   0:00  |               \_ docker pull registry.aliyuncs.com/google_containers/etcd:3.4.3-0
…

init输出内容中需要注意的地方:

生成配置文件

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

配置网络

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/

添加worker node到集群

Then you can join any number of worker nodes by running the following on each as root:
 
kubeadm join 192.168.219.130:6443 --token up139x.98qlng4m7qk61p0z 
    --discovery-token-ca-cert-hash sha256:c718e29ccb1883715489a3fdf53dd810a7764ad038c50fd62a2246344a4d9a73

2,查看init操作下载的images

[root@kubemaster ~]# docker images
REPOSITORY                                                        TAG      IMAGE ID      CREATED       SIZE
registry.aliyuncs.com/google_containers/kube-proxy                v1.18.3  3439b7546f29  3 weeks ago   117MB
registry.aliyuncs.com/google_containers/kube-apiserver            v1.18.3  7e28efa976bd  3 weeks ago   173MB
registry.aliyuncs.com/google_containers/kube-controller-manager   v1.18.3  da26705ccb4b  3 weeks ago   162MB
registry.aliyuncs.com/google_containers/kube-scheduler            v1.18.3  76216c34ed0c  3 weeks ago   95.3MB
registry.aliyuncs.com/google_containers/pause                     3.2      80d28bedfe5d  4 months ago  683kB
registry.aliyuncs.com/google_containers/coredns                   1.6.7    67da37a9a360  4 months ago  43.8MB
registry.aliyuncs.com/google_containers/etcd                      3.4.3-0  303ce5db0e90  7 months ago  288MB

3,添加kubectl的默认配置

注意：这些就是 kubeadm init的提示命令

按命令执行一遍即可:

生成.kube这个隐藏目录

[root@kubemaster ~]# mkdir -p $HOME/.kube

把admin.conf复制为config文件

[root@kubemaster ~]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

配置config文件的所有者

[root@kubemaster ~]# chown $(id -u):$(id -g) $HOME/.kube/config

查看效果

[root@kubemaster ~]# ll .kube/config
-rw------- 1 root root 5451 6月  16 18:25 .kube/config

四,安装网络插件 

1,查看node/pod

查看node

[root@kubemaster ~]# kubectl get node
NAME         STATUS     ROLES    AGE     VERSION
kubemaster   NotReady   master   5m39s   v1.18.3

查看pod

[root@kubemaster ~]# kubectl get pod --all-namespaces
NAMESPACE     NAME                                 READY   STATUS    RESTARTS   AGE
kube-system   coredns-7ff77c879f-ttnr9             0/1     Pending   0          6m41s
kube-system   coredns-7ff77c879f-x5vps             0/1     Pending   0          6m41s
kube-system   etcd-kubemaster                      1/1     Running   0          6m40s
kube-system   kube-apiserver-kubemaster            1/1     Running   0          6m40s
kube-system   kube-controller-manager-kubemaster   1/1     Running   0          6m40s
kube-system   kube-proxy-gs7q7                     1/1     Running   0          6m40s
kube-system   kube-scheduler-kubemaster            1/1     Running   0          6m40s 

说明:node状态是NotReady

pod中coredns的状态是Pending

原因在于我们还没有安装网络pod

 

2,安装calico

calico的用途?

calico是一个虚拟网络解决方案，

它利用路由规则实现动态组网，

通过BGP协议通告路由

[root@kubemaster ~]# kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

然后稍后查看pod状态:

[root@kubemaster ~]# kubectl get pod --all-namespaces
NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE
kube-system   calico-kube-controllers-76d4774d89-nnp4h   1/1     Running   0          20m
kube-system   calico-node-xmmj4                          1/1     Running   0          20m
kube-system   coredns-7ff77c879f-ttnr9                   1/1     Running   0          36m
kube-system   coredns-7ff77c879f-x5vps                   1/1     Running   0          36m
kube-system   etcd-kubemaster                            1/1     Running   1          36m
kube-system   kube-apiserver-kubemaster                  1/1     Running   1          36m
kube-system   kube-controller-manager-kubemaster         1/1     Running   1          36m
kube-system   kube-proxy-gs7q7                           1/1     Running   1          36m
kube-system   kube-scheduler-kubemaster                  1/1     Running   1          36m

状态都是Running,表示网络插件安装无误

查看node状态:

[root@kubemaster ~]# kubectl get node
NAME         STATUS   ROLES    AGE   VERSION
kubemaster   Ready    master   41m   v1.18.3

状态已变成了Ready 

查看calico安装的镜像:

[root@kubemaster ~]# docker images | grep calico
calico/node                 v3.14.1    04a9b816c753        2 weeks ago         263MB
calico/pod2daemon-flexvol   v3.14.1    7f93af2e7e11        2 weeks ago         112MB
calico/cni                  v3.14.1    35a7136bc71a        2 weeks ago         225MB
calico/kube-controllers     v3.14.1    ac08a3af350b        2 weeks ago         52.8MB

3,安装colico后报错的一个情况:

如果pod的状态出现Init:ImagePullBackOff或Init:ErrImagePull,

 表示docker在下载calico的镜像时出错:

可以在docker的配置文件中增加aliyun的镜像地址:

例如：

[root@kubemaster ~]# more /etc/docker/daemon.json
{
"registry-mirrors":["https://o3trwnyj.mirror.aliyuncs.com"],
"exec-opts": ["native.cgroupdriver=systemd"]
}

修改完成后重启docker服务即可：

[root@kubemaster ~]# systemctl restart docker

五，开启单机模式：配置master节点也作为worker node可运行pod

1,删除原有的taint设置

[root@kubemaster ~]# kubectl taint nodes kubemaster node-role.kubernetes.io/master-
node/kubemaster untainted

说明：此命令的作用是删除taint

 

2,如何查看当前taint的情况？

[root@kubemaster ~]# kubectl describe node kubemaster

Taints:一项的值如果是:<none>，表示删除taint成功

说明：如果要取消master节点运行pod,使用下面的命令:

kubectl taint nodes kubemaster node-role.kubernetes.io/master=:NoSchedule

这个命令作用是指定:master上的taint权限是:一定不能被调度

三个取值的含义分别是:

NoSchedule: 一定不能被调度
PreferNoSchedule: 尽量不要调度
NoExecute: 不仅不会调度, 还会驱逐Node上已有的Pod

说明：默认值就是: node-role.kubernetes.io/master:NoSchedule

 

六，测试:在master上运行一个tomcat容器:

1,生成rc的配置文件

[root@kubemaster k8s]# vi tomcat-rc.yaml

内容:

apiVersion: v1
kind: ReplicationController
metadata:
  name: tomcat-demo
spec:
  replicas: 1
  selector:
    app: tomcat-demo
  template:
    metadata:
      labels:
        app: tomcat-demo
    spec:
      containers:
      - name: tomcat-demo
        image: tomcat
        ports:
        - containerPort: 8080

2,创建rc

[root@kubemaster k8s]# kubectl apply -f tomcat-rc.yaml
replicationcontroller/tomcat-demo created

 

查看效果

[root@kubemaster k8s]# kubectl get pods
NAME                READY   STATUS              RESTARTS   AGE
tomcat-demo-7pnzw   0/1     ContainerCreating   0          23s

 

状态变为running后可用:

[root@kubemaster k8s]# kubectl get pods
NAME                READY   STATUS    RESTARTS   AGE
tomcat-demo-7pnzw   1/1     Running   0          6m43s

 

查看ip:

[root@kubemaster k8s]# kubectl get pods -o wide
NAME                READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
tomcat-demo-7pnzw   1/1     Running   0          10m   172.16.141.7   kubemaster   <none>           <none>

在宿主机上用curl查看，这个默认是一个404报错页面,

[root@kubemaster k8s]# curl http://172.16.141.7:8080
<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title>
<style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} 
h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} 
.line {height:1px;background-color:#525D76;border:none;}</style></head>
<body><h1>HTTP Status 404 – Not Found</h1><hr class="line" /><p><b>Type</b> Status Report</p>
<p><b>Description</b> The origin server did not find a current representation for the target resource 
or is not willing to disclose that one exists.</p>
<hr class="line" /><h3>Apache Tomcat/9.0.36</h3>
</body></html>

因为webapps目录下没有可显示的内容 

我们登录到容器手动调整一下:

登录到tomcat容器，

[root@kubemaster k8s]# docker exec -it k8s_tomcat-demo_tomcat-demo-7pnzw_default_b59ef37a-6ffe-4ef1-b6dd-1b2186039294_0 /bin/bash  

复制文件到webapps目录下:

root@tomcat-demo-7pnzw:/usr/local/tomcat# cp -axv webapps.dist/* webapps/

用curl查看效果:

[root@kubemaster ~]# curl http://172.16.141.7:8080/
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <title>Apache Tomcat/9.0.36</title>
        <link href="favicon.ico" rel="icon" type="image/x-icon" />
        <link href="favicon.ico" rel="shortcut icon" type="image/x-icon" />
        <link href="tomcat.css" rel="stylesheet" type="text/css" />
    </head>
 
    <body>
        <div id="wrapper">
            <div id="navigation" class="curved container">
                <span id="nav-home"><a href="https://tomcat.apache.org/">Home</a></span>
                <span id="nav-hosts"><a href="/docs/">Documentation</a></span>
                <span id="nav-config"><a href="/docs/config/">Configuration</a></span>
                <span id="nav-examples"><a href="/examples/">Examples</a></span>
                <span id="nav-wiki"><a href="https://wiki.apache.org/tomcat/FrontPage">Wiki</a></span>
                <span id="nav-lists"><a href="https://tomcat.apache.org/lists.html">Mailing Lists</a></span>
                <span id="nav-help"><a href="https://tomcat.apache.org/findhelp.html">Find Help</a></span>
                <br class="separator" />
            </div>
…

可以正常显示了

3,生成service配置文件

说明：service此处的作用是把容器端口映射到宿主机端口，允许通过宿主机ip访问

[root@kubemaster k8s]# vi tomcat-svc.yaml 

内容:

apiVersion: v1
kind: Service
metadata:
  name: tomcat-demo
spec:
  type: NodePort
  ports:
   - port: 8080
     nodePort: 30010
  selector:
    app: tomcat-demo

4,创建service

[root@kubemaster k8s]# kubectl apply -f tomcat-svc.yaml
service/tomcat-demo created

查看service是否创建成功?

[root@kubemaster k8s]# kubectl get service -o wide
NAME          TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE   SELECTOR
kubernetes    ClusterIP   10.96.0.1        <none>        443/TCP          18h   <none>
tomcat-demo   NodePort    10.111.234.185   <none>        8080:30010/TCP   35s   app=tomcat-demo 

测试用浏览器从外部访问:

如图:

 

 

 七，查看linux的版本 

[root@kubemaster ~]# cat /etc/redhat-release
CentOS Linux release 8.2.2004 (Core)
[root@kubemaster ~]# uname -r
4.18.0-193.el8.x86_64