K3s 是由 Rancher Labs 于今年年初发布的一款开源、极轻量的Kubernetes发行版，完美适用于在资源有限的环境中运行 Kubernetes。K3s 一经发布就得到了业界的高度关注和认可，发布半年以来已在 GitHub 上拥有近 8500 颗 Star 。
最初 k3s 只是一个用于本地 Kubernetes 开发的 POC 项目，而如今已有很多企业用户在生产环境中使用它。
官方 GitRepo:
https://github.com/rancher/k3s
官方定义：k3s 是完全符合标准的生产级 Kubernetes 发行版，具有以下四个方面的主要变化：
删除旧的、非必须的代码： K3s 不包括任何默认禁用的 Alpha 功能或者过时的功能，原有的 API 组件目前仍运行于标准部署当中。除此之外，Rancher 还删除了所有非默认许可控制器，in- tree 云提供商和存储驱动程序，但允许用户添加任何他们需要的驱动程序。
整合正在运行的打包进程：为了节省 RAM，Rancher 将通常在 Kubernetes 管理服务器上运行的多流程合并为单个流程。Rancher 还将在工作节点上运行的 kubelet、kubeproxy 和 flannel 代理进程组合成一个进程。
使用 containerd 代替 Docker 作为运行时的容器引擎： 通过用 containderd 替换 Docker，Rancher 能够显著减少运行时占用空间，删除 libnetwork、swarm、Docker 存储驱动程序和其他插件等功能。
除了 etcd 之外，引入 SQLite 作为可选的数据存储： Rancher 在 k3s 中添加了 SQLite 作为可选的数据存储，从而为 etcd 提供了一个轻量级的替代方案。该方案不仅占用了较少的内存，而且大幅简化了操作。
鉴于 k3s 受到极高的关注度以及广泛的应用，大量的开源社区用户开始搭建有关 k3s 的项目，本文将分享如何使用其中一个项目——k3sup，来实现一分钟内从零到完全配置 k3s Kubeconfig。
K3sup：1 分钟之内，从零到完全配置 Kubeconfig
K3sup：https://github.com/alexellis/k3sup
K3sup 是由 Alex Ellis 创建的一个开源项目，这使得 k3s 的安装和 kubeconfig 文件的生成变得快速和方便。这一工具能以极快的速度自动化安装 k3s、将 SAN 地址更新为公共 IP、下载 k3s 配置文件然后使用 VM 的公共 IP 地址将其更新，以便可以使用 kubectl 连接它。
以下步骤使用 Amazon EC2 实例说明了此过程：
步骤 1： 启动 Amazon EC2 实例，让安全组打开端口并通过 ssh 登录。
EC2 与 Amazon AMI 一起运行
步骤 2： 下载 k3sup 的二进制文件
curl -sLS https://raw.githubusercontent.com/alexellis/k3sup/master/get.sh | sh[root@ip-172-31-33-136 ec2-user]# curl -sLS https://raw.githubusercontent.com/alexellis/k3sup/master/get.sh | shwhich: no k3sup in (/sbin:/bin:/usr/sbin:/usr/bin)x86_64Downloading package https://github.com/alexellis/k3sup/releases/download/0.2.0/k3sup as /tmp/k3supDownload complete.
Running as root - Attempting to move k3sup to /usr/local/binNew version of k3sup installed to /usr/local/bin
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步骤 3： 将 ssh 密钥复制到 VM 中的’vi /root/.ssh/id_rsa’位置，导出 IP 并使用 k3sup 安装 k3s
[root@ip-172-31-33-136 ec2-user]# **cd /usr/local/bin**
[root@ip-172-31-33-136 bin]# **export IP=54.159.112.255**
[root@ip-172-31-33-136 bin]# **./k3sup install --ip $IP --user ec2-user**
Public IP: 54.159.112.255ssh -i /root/.ssh/id_rsa ec2-user@54.159.112.255
ssh: curl -sLS https://get.k3s.io | INSTALL_K3S_EXEC='server --tls-san 54.159.112.255' sh -[INFO] Finding latest release[INFO] Using v0.8.0 as release[](https://github.com/rancher/k3s/releases/download/v0.8.0/sha256sum-amd64.txt)[](https://github.com/rancher/k3s/releases/download/v0.8.0/k3s)[INFO] Verifying binary download[INFO] Installing k3s to /usr/local/bin/k3swhich: no kubectl in (/usr/local/bin:/usr/bin)[INFO] Creating /usr/local/bin/kubectl symlink to k3swhich: no crictl in (/usr/local/bin:/usr/bin)[INFO] Creating /usr/local/bin/crictl symlink to k3swhich: no ctr in (/usr/local/bin:/usr/bin)[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 unitCreated symlink from /etc/systemd/system/multi-user.target.wants/k3s.service to /etc/systemd/system/k3s.service.[INFO] systemd: Starting k3sResult: [INFO] Finding latest release[INFO] Using v0.8.0 as release[](https://github.com/rancher/k3s/releases/download/v0.8.0/sha256sum-amd64.txt)[](https://github.com/rancher/k3s/releases/download/v0.8.0/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[INFO] systemd: Starting k3swhich: no kubectl in (/usr/local/bin:/usr/bin)which: no crictl in (/usr/local/bin:/usr/bin)which: no ctr in (/usr/local/bin:/usr/bin)Created symlink from /etc/systemd/system/multi-user.target.wants/k3s.service to /etc/systemd/system/k3s.service.
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它将创建一个 kubeconfig 文件并且保存在你运行命令的目录中。
步骤 4： 导出 KUBECONFIG
[root@ip-172-31-33-136 bin]#** export KUBECONFIG=`pwd`/kubeconfig**
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步骤 5： 开始玩转 k3s
[root@ip-172-31-33-136 bin]# **./kubectl get nodes**
NAME STATUS ROLES AGE VERSION
ip-172-31-33-136.ec2.internal Ready master 24s v1.14.5-k3s.1
[root@ip-172-31-33-136 bin]# **./kubectl get pods -n kube-system**
NAME READY STATUS RESTARTS AGE
coredns-b7464766c-ngf46 1/1 Running 0 4m3s
helm-install-traefik-x6wfj 0/1 Completed 0 4m3s
svclb-traefik-65gw9 2/2 Running 0 3m49s
traefik-56688c4464-5rdss 1/1 Running 0 3m49s
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运行一个简单的服务：
# Create a Deployment**./kubectl run nginx --image=nginx**
# Create Service[root@ip-172-31-33-136 bin]# **./kubectl expose deployment nginx --port=80 --target-port=80**
service/nginx exposed
[root@ip-172-31-33-136 bin]# **./kubectl get svc**
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.43.0.1 <none> 443/TCP 45m
nginx ClusterIP 10.43.99.179 <none> 80/TCP 5s
[root@ip-172-31-33-136 bin]# **curl 10.43.99.179**
<!DOCTYPE html><html><head><title>Welcome to nginx!</title><style>body {width: 35em;margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif;}</style></head><body><h1>Welcome to nginx!</h1><p>If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.</p><p>For online documentation and support please refer to<a href="http://nginx.org/">nginx.org</a>.<br/>Commercial support is available at<a href="http://nginx.com/">nginx.com</a>.</p><p><em>Thank you for using nginx.</em></p></body></html>
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加入两个节点：是否可以在不登录节点的情况下将节点与主节点连接？是的，k3sup 可以做到这一点。
在 VM 上获得 k3s 设置后，你可以轻松地将节点加入到集群：
#AGENT_IP is the IP of the VM that you want to add to the cluster that has k3s running**export AGENT_IP=54.196.113.156**
#SERVER_IP is the IP of the server where k3 is installed export SERVER_IP=54.159.112.255**export USER=ec2-user**
[root@ip-172-31-33-136 bin]# **./k3sup join --ip $AGENT_IP --server-ip $SERVER_IP --user ec2-user**Server IP: 54.159.112.255ssh -i /root/.ssh/id_rsa ec2-user@54.159.112.255ssh: sudo cat /var/lib/rancher/k3s/server/node-token
K1077d707d0868b652aca7adfc21b5f34a1f0357e71b216bf8b3c94a559cd4f93a6::node:014c8ed3f6574d27db73b9c8bf67f617
ssh: curl -sfL https://get.k3s.io/ | K3S_URL="https://54.159.112.255:6443" K3S_TOKEN="K1077d707d0868b652aca7adfc21b5f34a1f0357e71b216bf8b3c94a559cd4f93a6::node:014c8ed3f6574d27db73b9c8bf67f617" sh -
[INFO] Finding latest release[INFO] Using v0.8.0 as release[](https://github.com/rancher/k3s/releases/download/v0.8.0/sha256sum-amd64.txt)[](https://github.com/rancher/k3s/releases/download/v0.8.0/k3s)[INFO] Verifying binary download[INFO] Installing k3s to /usr/local/bin/k3swhich: no kubectl in (/usr/local/bin:/usr/bin)[INFO] Creating /usr/local/bin/kubectl symlink to k3swhich: no crictl in (/usr/local/bin:/usr/bin)[INFO] Creating /usr/local/bin/crictl symlink to k3swhich: no ctr in (/usr/local/bin:/usr/bin)[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 unitCreated symlink from /etc/systemd/system/multi-user.target.wants/k3s-agent.service to /etc/systemd/system/k3s-agent.service.[INFO] systemd: Starting k3s-agentLogs: which: no kubectl in (/usr/local/bin:/usr/bin)which: no crictl in (/usr/local/bin:/usr/bin)which: no ctr in (/usr/local/bin:/usr/bin)Created symlink from /etc/systemd/system/multi-user.target.wants/k3s-agent.service to /etc/systemd/system/k3s-agent.service.Output: [INFO] Finding latest release[INFO] Using v0.8.0 as release[](https://github.com/rancher/k3s/releases/download/v0.8.0/sha256sum-amd64.txt)[](https://github.com/rancher/k3s/releases/download/v0.8.0/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[INFO] systemd: Starting k3s-agent
[root@ip-172-31-33-136 bin]# **./kubectl get nodes**
NAME STATUS ROLES AGE VERSION
ip-172-31-33-136.ec2.internal Ready master 19m v1.14.5-k3s.1
ip-172-31-37-118.ec2.internal Ready worker 11s v1.14.5-k3s.1
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你可以看到使用 k3sup 设置 k3s 集群并在不到 60 秒的时间内将其作为 Amazon EC2 实例上运行的节点加入 VM 是如此容易。赶紧上手尝试吧！
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