仅需4步，轻松升级K3s集群！

Rancher 2.4是Rancher目前最新的版本，在这一版本中你可以通过Rancher UI对K3s集群进行升级管理。

K3s是一个轻量级Kubernetes发行版，借助它你可以几分钟之内设置你的开发Kubernetes环境。它非常适用于生产用例，主要用于IoT和Edge设备。
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在Rancher 2.4中，你可以导入K3s集群并且可以通过Rancher本身对其进行升级管理。在本篇教程中，我们将了解如何在一个正在运行的K3s集群上执行实时升级。

Step1：创建K3s集群

在执行升级之前，我们需要启动一个K3s集群。在本文中我是在一个CentOS VM上启动的，你可以在任意云上执行这一操作。

登录到VM，并运行以下命令：


**[root@demo3 ~]# curl -sfL [https://get.k3s.io](https://get.k3s.io) | INSTALL_K3S_VERSION="v1.0.1" sh -s -**

[INFO]  Using v1.0.1 as release
[INFO]  Downloading hash [https://github.com/rancher/k3s/releases/download/v1.0.1/sha256sum-amd64.txt](https://github.com/rancher/k3s/releases/download/v1.0.1/sha256sum-amd64.txt)
[INFO]  Downloading binary [https://github.com/rancher/k3s/releases/download/v1.0.1/k3s](https://github.com/rancher/k3s/releases/download/v1.0.1/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-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 k3sAbove will install k3s version

**[root@demo3 ~]# kubectl get  nodes**

NAME    STATUS   ROLES    AGE     VERSION
demo3   Ready    master   5m55s   **v1.16.3-k3s.2**

你可以看到我们在VM上已经安装了Kubernetes v1.16.3。

Step2：安装Rancher

为了从Rancher UI中执行升级，必须通过以下命令安装Rancher：

**[root@demo3 ~]# sudo docker run -d --restart=unless-stopped -p 80:80 -p 443:443 rancher/rancher
**Unable to find image 'rancher/rancher:latest' locally
Trying to pull repository docker.io/rancher/rancher ...
latest: Pulling from docker.io/rancher/rancher
5bed26d33875: Pull complete
f11b29a9c730: Pull complete
930bda195c84: Pull complete
78bf9a5ad49e: Pull complete
fdb587a45dfe: Pull complete
0c3f7647a659: Pull complete
02c5407ca821: Pull complete
ebc009758b56: Pull complete
57a6e40f0f6e: Pull complete
30a88d01aca6: Pull complete
76505b705d6f: Pull complete
e585ea16af8d: Pull complete
6b069694034e: Pull complete
8c5d309f94d1: Pull complete
8ec56f5fa6c2: Pull complete
75872eb736b7: Pull complete
e774fd043162: Pull complete
c76d81e7a658: Pull complete
49bf6b83af1c: Pull complete
Digest: sha256:248ddca1169e8a4e06babd50e8105cbba0a326f86ec4de3e38d61e8909ffdb4e
Status: Downloaded newer image for docker.io/rancher/rancher:latest
ef7f9a0d5bca831af19900a6ceafd30daca51e4f951295762cf7516e48d3d742

Step3：在Rancher中导入集群

打开Rancher UI并点击以下按钮导入K3s集群：

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复制最后一条命令并在安装了K3s的VM上运行该命令：

**[root@demo3 ~]# curl --insecure -sfL [https://185.136.232.236/v3/import/pxv5g7xswnnqkhl4dx7nrn8swndwshk9g8426lnldrvt7vjvfc2fgr.yaml](https://185.136.232.236/v3/import/pxv5g7xswnnqkhl4dx7nrn8swndwshk9g8426lnldrvt7vjvfc2fgr.yaml) | kubectl apply -f -**
clusterrole.rbac.authorization.k8s.io/proxy-clusterrole-kubeapiserver created
clusterrolebinding.rbac.authorization.k8s.io/proxy-role-binding-kubernetes-master created
namespace/cattle-system created
serviceaccount/cattle created
clusterrolebinding.rbac.authorization.k8s.io/cattle-admin-binding created
secret/cattle-credentials-d6e5b6d created
clusterrole.rbac.authorization.k8s.io/cattle-admin created
deployment.apps/cattle-cluster-agent created
daemonset.apps/cattle-node-agent created

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