K3s:轻量的Kubernetes

K3s是一个轻量的K8s，主要面向IOT、Edge、CI等场景。

K3s和K8s的对比，移除了：

• 非默认的、遗留的特性
• Alpha阶段的特性
• In-tree的云服务提供商
• In-tree的存储驱动
• Docker (可选)

带来了：

• 简化安装
• SQLite3支持，替代etcd
• TLS管理
• 自动的Manifest和Helm Chart管理
• containerd, CoreDNS, Flannel

快速安装

## 下载镜像，避免无网络或访问不了gcr.io
$ wget https://github.com/rancher/k3s/releases/download/v0.3.0/k3s-airgap-images-amd64.tar
$ sudo mkdir -p /var/lib/rancher/k3s/agent/images/
$ sudo cp k3s-airgap-images-amd64.tar  /var/lib/rancher/k3s/agent/images/

## 安装
$ curl -sfL https://get.k3s.io | sh -
[INFO]  Finding latest release
[INFO]  Using v0.3.0 as release
[INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v0.3.0/sha256sum-amd64.txt
[INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v0.3.0/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 uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO]  systemd: 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 /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
[INFO]  systemd: Starting k3s

完成后就可以用kubectl正常访问k3s：

$ kubectl get pods --all-namespaces
kubectl get pods --all-namespaces
NAMESPACE     NAME                             READY   STATUS      RESTARTS   AGE
kube-system   coredns-7748f7f6df-phxck         1/1     Running     33         38d
kube-system   helm-install-traefik-8tjss       0/1     Completed   0          51s
kube-system   svclb-traefik-78cbd58b59-smdf8   2/2     Running     0          51s
kube-system   traefik-5cc8776646-x9bw9         1/1     Running     0          34s

$ kubectl get nodes
NAME          STATUS   ROLES    AGE     VERSION
archlinux     Ready    <none>   43m48s   v1.13.5-k3s.1

注意：K3s默认使用containerd，要使用docker需要设置--docker:

curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC="--docker" sh -

更多的安装方式和配置可以参考文档。