k3s-(1)k3s主从安装

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部署轻量级Kubernetes集群来减少内存占用，那么你一定要考虑由Rancher Labs发布的轻量级Kubernetes发行版——k3s。

它把安装Kubernetes所需的一切文件都打包进一个40MB大小的二进制文件中，仅需512MB的RAM即可运行。非常适用于资源有限的环境，如边缘计算场景、IoT等。
k3s is 5 less then k8s,直接翻译过来就是k3s比k8s少了5个字符，引申一下就是k3s就是k8s的简化版。可以看做k8s的一个衍生版，特点就是轻量。
具体描述请看官方文档 https://docs.rancher.cn/k3s/#_1-what-is-this

1.k3s主节点安装

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hostnamectl set-hostname 192.168.67.125

使用以下方法加速安装：

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curl -sfL https://docs.rancher.cn/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -

安装后输出：

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[INFO]  Finding latest release
[INFO]  Using v1.17.4+k3s1 as release
[INFO]  Downloading hash mirror-k3s.rancher.cn/download/v1.17.4-k3s1/sha256sum-amd64.txt
[INFO]  Downloading binary mirror-k3s.rancher.cn/download/v1.17.4-k3s1/k3s
[INFO]  Verifying binary download
[INFO]  Installing k3s to /usr/local/bin/k3s
[INFO]  Skipping /usr/local/bin/kubectl symlink to k3s, command exists in PATH at /usr/bin/kubectl
[INFO]  Skipping /usr/local/bin/crictl symlink to k3s, command exists in PATH at /usr/bin/crictl
[INFO]  Skipping /usr/local/bin/ctr symlink to k3s, command exists in PATH at /usr/bin/ctr
[INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
[INFO]  Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO]  env: Creating environment file /etc/systemd/system/k3s.service.env
[INFO]  systemd: Creating service file /etc/systemd/system/k3s.service
[INFO]  systemd: Enabling k3s unit
Created symlink from /etc/systemd/system/multi-user.target.wants/k3s.service to /etc/systemd/system/k3s.service.
[INFO]  systemd: Starting k3s

安装完成之后，服务会自动启动

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systemctl status k3s

● k3s.service - Lightweight Kubernetes
   Loaded: loaded (/etc/systemd/system/k3s.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2020-04-13 09:01:03 EDT; 16min ago
     Docs: https://k3s.io
  Process: 5513 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
  Process: 5511 ExecStartPre=/sbin/modprobe br_netfilter (code=exited, status=0/SUCCESS)
 Main PID: 5515 (k3s-server)
   Memory: 388.0M
   CGroup: /system.slice/k3s.service
           └─5548 containerd -c /var/lib/rancher/k3s/agent/etc/containerd/config.toml -a /run/k3s/containerd/containerd.sock --state /run/k3s/containerd --root /var/lib/rancher/k3s/agent/containerd
           ‣ 5515 /usr/local/bin/k3s server

安装完成后，我们需要调整下K3S的服务配置文件，以将K3S的默认容器引擎从Containerd切换到Docker。

1.2修改K3S服务的配置文件：

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vim /etc/systemd/system/multi-user.target.wants/k3s.service

文件内容如下：

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[Unit] 
Description=Lightweight Kubernetes 
Documentation=https://k3s.io 
After=network-online.target 
[Service] 
Type=notify 
EnvironmentFile=/etc/systemd/system/k3s.service.env 
ExecStartPre=-/sbin/modprobe br_netfilter 
ExecStartPre=-/sbin/modprobe overlay 
ExecStart=/usr/local/bin/k3s server 
KillMode=process 
Delegate=yes 
LimitNOFILE=infinity 
LimitNPROC=infinity 
LimitCORE=infinity 
TasksMax=infinity 
TimeoutStartSec=0 
Restart=always 
[Install] 
WantedBy=multi-user.targe

在这里我们需要修改ExecStart的值，将其修改为：

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/usr/local/bin/k3s server --docker --no-deploy traefik

之后保存退出，执行命令重新加载新的服务配置文件：

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systemctl daemon-reload

完成后重启K3S服务：

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service k3s restart

稍等数十秒，之后通过命令确认K3S集群是否就绪：

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k3s kubectl get node

如果得到类似如下的结果：

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NAME                  STATUS   ROLES    AGE     VERSION 

k3s01.ilemonrain.io   Ready    <none>   3m34s   v1.14.1-k3s.4

则说明K3S集群启动成功。

1.3添加worker节点：

在agent节点上安装并将它们添加到现有集群中，应该传递环境变量K3S_URL，并且还需要同时传递K3S_TOKEN或者K3S_CLUSTER_SECRET。

K3S_TOKEN创建在/var/lib/rancher/k3s/server/node-token

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cat /var/lib/rancher/k3s/server/node-token K1042e2f8e353b9409472c1e0cca8457abe184dc7be3f0805109e92c50c193ceb42::node:c83acbf89a7de7026d6f6928dc270028

设置IP，获取主节点token,加入主节点集群

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hostnamectl set-hostname 192.168.67.125

curl -sfL https://docs.rancher.cn/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn K3S_URL=https://192.168.67.128:6443 K3S_TOKEN=K1074138cd2c349e75454219b38de8eac0aad401ab80e3135c49d93a51db92bf8f7::server:8c956ed05c36e14b2a8085eb47d13445 sh -

安装完成后

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[INFO]  Finding latest release [INFO]  Using v0.8.1 as release 
[INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v0.8.1/sha256sum-amd64.txt
[INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v0.8.1/k3s 
[INFO]  Verifying binary download
[INFO]  Installing k3s to /usr/local/bin/k3s 
[INFO]  Creating /usr/local/bin/kubectl symlink to k3s 
[INFO]  Creating /usr/local/bin/crictl symlink to k3s
[INFO]  Creating /usr/local/bin/ctr symlink to k3s 
[INFO]  Creating killall script /usr/local/bin/k3s-killall.sh 
[INFO]  Creating uninstall script /usr/local/bin/k3s-agent-uninstall.sh
[INFO]  env: Creating environment file /etc/systemd/system/k3s-agent.service.env 
[INFO]  systemd: Creating service file /etc/systemd/system/k3s-agent.service 
[INFO]  systemd: Enabling k3s-agent unit Created symlink /etc/systemd/system/multi-user.target.wants/k3s-agent.service → /etc/systemd/system/k3s-agent.service.
[INFO]  systemd: Starting k3s-agent

验证安装:

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systemctl status k3s-agent

如果 Active: active (running) 说明启动成功

查看agent节点是否已经加入到了集群中：

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k3s kubectl get nodes 
NAME         STATUS   ROLES    AGE   VERSION 
test01-201   Ready    master   12h   v1.15.4-k3s.1 
test02-202   Ready    worker   11h   v1.15.4-k3s.1

安装完成后，我们需要

1.4修改下K3S-agent的服务配置文件

，以将K3S的默认容器引擎从Containerd切换到Docker。

修改K3S-agent服务的配置文件，以将K3S-agent的默认容器引擎从Containerd切换到Docker

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vim /etc/systemd/system/multi-user.target.wants/k3s-agent.service

service k3s-agent restart

在这里我们需要修改ExecStart的值，将其修改为：

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/usr/local/bin/k3s-agent server --docker --no-deploy traefik

之后保存退出，执行命令重新加载新的服务配置文件：

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systemctl daemon-reload

完成后重启K3S-agent服务：

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service k3s-agent restart

1.5最后检查服务是安装成功

检查pod的状态：

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k3s kubectl get po --all-namespaces
NAMESPACE       NAME                                      READY   STATUS    RESTARTS   AGE
kube-system     svclb-traefik-9x9d8                       2/2     Running   0          15h
cattle-system   cattle-node-agent-zmxvg                   1/1     Running   0          15h
kube-system     svclb-traefik-zdm8v                       2/2     Running   0          5m11s
cattle-system   cattle-node-agent-2xhzx                   1/1     Running   0          5m11s
kube-system     local-path-provisioner-58fb86bdfd-q6klf   1/1     Running   0          91s
kube-system     metrics-server-6d684c7b5-l5kts            1/1     Running   0          91s
cattle-system   cattle-cluster-agent-768f7755c9-knjg8     1/1     Running   0          91s
kube-system     coredns-6c6bb68b64-kjrgd                  1/1     Running   0          91s
kube-system     traefik-7b8b884c8-dk4t7                   1/1     Running   0          91s
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kubectl get pods -A

查看服务安装失败具体信息

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kubectl describe pods coredns-d798c9dd-mpbpc -n kube-system

k3s版本信息

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k3s --version
k3s version v1.0.0 (18bd921c)

1.6可能出现的问题：

如果从节点有卸载后重装

server将在单个节点的/var/lib/rancher/k3s/server/cred/node-passwd路径存储密码, worker节点将使用节点集群密钥以及存储在/etc/rancher/node/password

2个必须保持一致

大功告成啦！
如果你需要更高级的配置，请参阅K3S官方文档：https://docs.rancher.cn/k3s/#_1-what-is-this

部分截图



参考地址
https://juejin.im/post/5dc915dbf265da4d1d330160
https://blog.csdn.net/qq_43792385/article/details/104613119
https://segmentfault.com/a/1190000020877212

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