Just 5分鐘！使用k3s部署輕量Kubernetes集羣快速教程

時間  2020-02-09
標籤 5分 使用 k3s 部署 輕量 kubernetes 集羣 快速 教程 欄目 負載均衡 简体版
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大小僅有40MB的k3s爲想要節省開銷進行開發和測試的企業提供了一個很好的選擇。本文將用一種極爲簡潔的方式，教你在5分鐘以內使用k3s部署輕量Kubernetes集羣。node

本文來自：Rancher Labslinux

Kubernetes已經改變了如何大規模部署和管理容器化工做負載。如今開發人員面臨的挑戰主要在於設置過程的複雜性和資源需求量巨大。若是你深受內存不足的困擾，想要部署輕量級Kubernetes集羣來減小內存佔用，那麼你必定要考慮由Rancher Labs發佈的輕量級Kubernetes發行版——k3s。它把安裝Kubernetes所需的一切文件都打包進一個40MB大小的二進制文件中，僅需512MB的RAM便可運行。很是適用於資源有限的環境，如邊緣計算場景、IoT等。git

在實際場景中，爲了得到開發和測試的動力，節省開銷，用戶但願可以以最少的資源利用率和較低的硬件規格來部署Kubernetes。而k3s正好知足了這一需求，它可以在任何512MB RAM以上的設備上運行集羣，如IoT設備或ARM驅動的設備。github

既然k3s僅需少許資源便可運行，那麼這意味着一些Kubernetes的特性被移除了：sql

  • 舊的、非默認的、alpha功能
  • 大部分in-tree插件（雲提供商和存儲插件），將其用附加組件進行替換
  • 用sqlite來代替etcd做爲默認存儲機制

5分鐘以內使用k3s部署輕量K8s集羣

在本文中，我將使用運行在Debian 10上的3個server，每一個server有1GB的RAM和1vcpu。其中一個server做爲master，其餘兩個做爲worker節點。api

$ openstack server list
+--------------------------------------+-------------------+---------+-----------------------------------+-----------+-----------+
| ID                                   | Name              | Status  | Networks                          | Image     | Flavor    |
+--------------------------------------+-------------------+---------+-----------------------------------+-----------+-----------+
| 4df6a6dc-26e8-4ae0-8b6e-2f97daec0ef3 | k3s-master        | ACTIVE  | private=10.10.1.159               | Debian-10 | m1.tiny   |
| 5ca13239-b745-4f62-ab11-0a27949c9b35 | k3s-node02        | ACTIVE  | private=10.10.1.142               | Debian-10 | m1.tiny   |
| a54997f2-4d94-4718-86ab-73609b328761 | k3s-node01        | ACTIVE  | private=10.10.1.126               | Debian-10 | m1.tiny   |
+--------------------------------------+-------------------+---------+-----------------------------------+-----------+-----------+

我將在每一個服務器的/ etc / hosts文件中爲服務器添加A record。bash

sudo tee -a /etc/hosts<<EOF
10.10.1.159 k3s-master
10.10.1.126 k3s-node01
10.10.1.142 k3s-node02
EOF

在Master節點上安裝k3s

運行k3s的方式有不少，最快的方式是經過提供的bash腳本進行安裝，同時該腳本提供了一個便捷的方式來安裝到systemd或openrc。服務器

curl -sfL https://get.k3s.io | sh -

安裝輸出：curl

[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-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 /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
[INFO]  systemd: Starting k3s

安裝完成以後，服務會自動啓動。測試

$ 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
     Docs: https://k3s.io
  Process: 833 ExecStartPre=/sbin/modprobe br_netfilter (code=exited, status=0/SUCCESS)
  Process: 836 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
 Main PID: 837 (k3s-server)
    Tasks: 98
   Memory: 571.1M
   CGroup: /system.slice/k3s.service
           ├─ 837 /usr/local/bin/k3s server KillMode=process
           ├─ 851 containerd -c /var/lib/rancher/k3s/agent/etc/containerd/config.toml -a /run/k3s/containerd/containerd.sock --state /run/k3s/conta
           ├─1110 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/f6eeb59978
           ├─1127 /pause
           ├─1207 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/0baf0ca181
           ├─1225 /coredns -conf /etc/coredns/Corefile
           ├─1576 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/dcce4b7e17
           ├─1594 /pause
           ├─1599 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/50816ffba8
           ├─1617 /pause
           ├─1824 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/d0ff393609
           ├─1842 /bin/sh /usr/bin/entry
           ├─1882 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/046779175f
           ├─1899 /bin/sh /usr/bin/entry
           ├─1904 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/93f0fe2361
           └─1921 /traefik --configfile=/config/traefik.toml

Sep 17 19:20:34 deb10 k3s[837]: E0917 19:20:34.714229     837 daemon_controller.go:302] kube-system/svclb-traefik failed with : error storing statu
Sep 17 19:20:34 deb10 k3s[837]: E0917 19:20:34.719452     837 daemon_controller.go:302] kube-system/svclb-traefik failed with : error storing statu
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726816     837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726836     837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726857     837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726869     837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:35 deb10 k3s[837]: I0917 19:20:35.529102     837 reconciler.go:181] operationExecutor.UnmountVolume started for volume "helm-traefik-t
Sep 17 19:20:35 deb10 k3s[837]: I0917 19:20:35.542858     837 operation_generator.go:799] UnmountVolume.TearDown succeeded for volume "kubernetes.i
Sep 17 19:20:35 deb10 k3s[837]: I0917 19:20:35.629277     837 reconciler.go:285] Volume detached for volume "helm-traefik-token-kjwrl" (UniqueName:
Sep 17 19:20:36 deb10 k3s[837]: W0917 19:20:36.355273     837 pod_container_deletor.go:75] Container "2f0c4a787b13c029d65aa865c1b473f5a7497cb6f9b92

將kubeconfig文件寫入/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

其餘已經安裝的有：

  • kubectl
  • crictl
  • k3s-killall.sh
  • k3s-uninstall.sh

在Worker節點上安裝k3s

要在Woker節點上安裝k3s，咱們應該將K3S_URL以及K3S_TOKEN或K3S_CLUSTER_SECRET環境變量一塊兒傳遞。

K3S_TOKEN在第一個節點上的/ var / lib / rancher / k3s / server / node-token中建立。

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

因此爲了在worker節點上安裝Kubernetes，我將運行：

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 -

安裝輸出：

[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

登陸到其中一個master節點並檢查集羣狀態：

$ 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命令來查看正在運行的容器

# 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

大功告成啦！若是你須要更高級的配置，請參閱k3s文檔：

https://rancher.com/docs/k3s/...

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