使用k3s部署轻量Kubernetes集群快速教程
k3s是轻量级的Kubernetes。安装简单，占用资源少，只需要512M内存就可以运行起来，所有的二进制程序都不到 100MB。自 2019 年 3 月发布以来，备受全球开发者们关注。至...
k3s是轻量级的Kubernetes。安装简单，占用资源少，只需要512M内存就可以运行起来，所有的二进制程序都不到 100MB。
自 2019 年 3 月发布以来，备受全球开发者们关注。至今，GitHub Stars 数已超过 16,000，成为了开源社区最受欢迎的边缘计算K8S解决方案。
k3s 专为在资源有限的环境中运行 Kubernetes 的研发和运维人员设计，将满足日益增长的在边缘计算环境中运行在 x86、ARM64 和 ARMv7 处理器上的小型、易于管理的 Kubernetes 集群需求。k3s 的发布，为开发者们提供了以“Rancher 2.X + k3s”为核心的从数据中心到云到边到端的 K8S 即服务（Kubernetes-as-a-Service），推动 KubernetesEverywhere。
为什么叫k3s？
我们希望安装的 Kubernetes 在内存占用方面只是原来一半的大小。Kubernetes 是一个 10 个字母的单词。所以，有 Kubernetes 一半大的东西就是一个 5 个字母的单词，简写为 K3S。K3s没有全称，也没有官方的发音。
使用k3s部署轻量K8s集群
在Master节点上安装k3s
运行k3s的方式有很多，最快的方式是通过提供的bash脚本进行安装，同时该脚本提供了一个便捷的方式来安装到systemd或openrc。
curl -sfL https://get.k3s.io | sh
安装完成之后，服务会自动启动。
$ systemctl status k3s
● k3s.service - Lightweight Kubernetes
Loaded: loaded (/etc/systemd/system/k3s.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-09-17 19:20:00 UTC; 2min 24s ago
将kubeconfig文件写入/etc/rancher/k3s/k3s.yaml：
$ cat /etc/rancher/k3s/k3s.yaml
cat: /etc/rancher/k3s/k3s.yaml: Permission denied
debian@deb10:~$ sudo cat /etc/rancher/k3s/k3s.yaml
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: 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
server: https://localhost:6443
name: default
contexts:
- context:
cluster: default
user: default
name: default
current-context: default
kind: Config
preferences: {}
users:
- name: default
user:
password: 2d99cae31c075743be704bb717ceaae8
username: admin
其他已经安装的有：
kubectl
crictl
k3s-killall.sh
k3s-uninstall.sh
在Worker节点上安装k3s
要在Woker节点上安装k3s，我们应该将K3S_URL以及K3S_TOKEN或K3S_CLUSTER_SECRET环境变量一起传递。
K3S_TOKEN在第一个节点上的/ var / lib / rancher / k3s / server / node-token中创建。
$ sudo cat /var/lib/rancher/k3s/server/node-token
K1042e2f8e353b9409472c1e0cca8457abe184dc7be3f0805109e92c50c193ceb42::node:c83acbf89a7de7026d6f6928dc270028
所以为了在worker节点上安装Kubernetes，我将运行：
k3s_url="https://k3s-master:6443"
k3s_token="K1042e2f8e353b9409472c1e0cca8457abe184dc7be3f0805109e92c50c193ceb42::node:c83acbf89a7de7026d6f6928dc270028"
curl -sfL https://get.k3s.io | K3S_URL=${k3s_url} K3S_TOKEN=${k3s_token} sh -
安装输出：
[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
登录到其中一个master节点并检查集群状态：
$ sudo kubectl config get-clusters
NAME
default
$ sudo kubectl cluster-info
Kubernetes master is running at https://localhost:6443
CoreDNS is running at https://localhost:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
$ sudo kubectl get nodes
NAME STATUS ROLES AGE VERSION
k3s-master Ready master 14m v1.14.6-k3s.1
k3s-node01 Ready worker 3m11s v1.14.6-k3s.1
k3s-node02 Ready worker 3m58s v1.14.6-k3s.1
$ sudo kubectl get namespaces
NAME STATUS AGE
default Active 16m
kube-node-lease Active 16m
kube-public Active 16m
kube-system Active 16m
$ sudo kubectl get endpoints -n kube-system
NAME ENDPOINTS AGE
kube-dns 10.42.0.2:53,10.42.0.2:53,10.42.0.2:9153 14m
traefik 10.42.0.5:80,10.42.0.5:443 14m
$ sudo kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-b7464766c-q9frk 1/1 Running 0 15m
helm-install-traefik-8dhpk 0/1 Completed 0 15m
svclb-traefik-9c2j8 2/2 Running 0 4m49s
svclb-traefik-bf9zd 2/2 Running 0 4m2s
svclb-traefik-v2fpx 2/2 Running 0 14m
traefik-5c79b789c5-k589d 1/1 Running 0 14m
使用crictl命令来查看正在运行的容器
# Master
$ sudo crictl ps
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT POD ID
acfafb50852d3 18471c10e6e4b 16 minutes ago Running traefik 0 bf8534452389f
fee5ac7e88f2e 4a065d8dfa588 16 minutes ago Running lb-port-443 0 e7068ff7ab2f2
bbab5b07e5efb 4a065d8dfa588 16 minutes ago Running lb-port-80 0 e7068ff7ab2f2
65c5d1333ea04 2ee68ed074c6e 16 minutes ago Running coredns 0 435c51f4716fc
# Workers
$ sudo crictl ps
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT POD ID
7ad5c83d6466f 4a065d8dfa588 6 minutes ago Running lb-port-443 0 bf8d9fe57c3f3
c1380eabc0b33 4a065d8dfa588 6 minutes ago Running lb-port-80 0 bf8d9fe57c3f3
https://rancher.com/docs/k3s/latest/en/
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