随着 Kube.NETes 成为主流的应用容器编排平台，其命令行客户端 kubectl 也成为了我们日常部署应用，维护集群最常用的工具。
kubectl 自身提供了强大的内置命令来满足我们对集群的操作，例如 get 获取集群内的资源对象，proxy 创建代理之类的，除了内置的这些自命令，kubectl 还提供了可扩展的能力，允许我们安装自己编写或者社区提供的插件来增强我们使用 kubectl 的生产力。
这里将给大家介绍如何在安装 kubectl 扩展插件，以及几款我在日常工作中常用到的社区提供的插件。
在安装和使用 kubectl 插件之前，请确保以及安装和配置好 kubectl 命令行工具和 git 工具。
首先介绍的第一款扩展插件就是 krew - k8s特别兴趣小组开发的一款用于安装和管理 kubectl 扩展插件的插件。
代码：
https://github.com/kubernetes-sigs/krew
(
set -x; cd "$(mktemp -d)" &&
OS="$(uname | tr '[:upper:]' '[:lower:]')" &&
ARCH="$(uname -m | sed -e 's/x86_64/amd64/' -e 's/(arm)(64)?.*/12/' -e 's/aarch64$/arm64/')" &&
KREW="krew-${OS}_${ARCH}" &&
curl -fsSLO "https://github.com/kubernetes-sigs/krew/releases/latest/download/${KREW}.tar.gz" &&
tar zxvf "${KREW}.tar.gz" &&
./"${KREW}" install krew
)
export PATH="${KREW_ROOT:-$HOME/.brew}/bin:$PATH"
然后重启你的终端。
❯ k krew version
OPTION VALUE
GitTag v0.4.3
GitCommit dbfefa5
IndexURI https://github.com/kubernetes-sigs/krew-index.git
BasePath /home/mengz/.krew
IndexPath /home/mengz/.krew/index/default
InstallPath /home/mengz/.krew/store
BinPath /home/mengz/.krew/bin
DetectedPlatform linux/amd64
alias krew='kubectl-krew'
echo "alias krew='kubectl-krew'" >> ~/.alias
这样就安装完成了，krew 是 kubectl 插件管理器，而 krew 自己又是插件，所以之后可以使用 krew 来更新 krew。
在 windows 上安装，请参考
https://krew.sigs.k8s.io/docs/user-guide/setup/install/ 。
使用示例
❯ krew list
PLUGIN VERSION
krew v0.4.3
❯ krew install [插件名]
❯ krew update
Updated the local copy of plugin index.
New plugins available:
* liqo
* switch-config
Upgrades available for installed plugins:
* open-svc v2.5.2 -> v2.5.3
* rbac-tool v1.7.1 -> v1.8.0
* rolesum v1.5.1 -> v1.5.5
❯ krew upgrade open-svc
Updated the local copy of plugin index.
Upgrading plugin: open-svc
❯ krew uninstall [插件名]
krew-index 里维护了上百款可通过 krew 直接安装的插件。接下来将介绍其他几款我日常使用的 kubectl 插件。
代码：
https://github.com/seredot/kubectl-example
安装 krew install example
example 插件可用于快速生成k8s资源对象的yaml文件示例，例如
❯ k example deploy
---
apiVersion: Apps/v1
kind: Deployment
metadata:
name: Nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80
当我们想临时通过资源声明文件部署应用的时候，可以使用该插件来生成模板。
代码：
https://github.com/kubectl-plus/kcf
安装： krew install fleet
fleet 插件可快速查看当前配置的集群的概览
❯ k fleet
CLUSTER VERSION NODES NAMESPACES PROVIDER API
homek8sc1 v1.23.8 3/3 4 ? https://k8sc1.mengz.lan:6443
api-sandbox-x8i5-p1-openshiftapps-com:6443 v1.23.5+9ce5071 ? ? ? https://api.sandbox.x8i5.p1.openshiftapps.com:6443
minikube v1.22.3 1/1 4 minikube https://192.168.64.3:8443
代码：
https://github.com/corneliusweig/ketall
安装： krew install get-all
get-all 插件获取集群（或者某一个名字空间）的所有资源对象
❯ k get-all -n kube-system
NAME NAMESPACE AGE
configmap/calico-config kube-system 13d
configmap/coreDNS kube-system 13d
configmap/extension-apiserver-authentication kube-system 13d
configmap/kube-proxy kube-system 13d
configmap/kube-root-ca.crt kube-system 13d
configmap/kubeadm-config kube-system 13d
configmap/kubelet-config-1.23 kube-system 13d
endpoints/kube-dns kube-system 13d
...
代码：
https://github.com/shibumi/kubectl-htpasswd
安装： krew install htpasswd
htpasswd 是 nginx-ingress 兼容的基础认证密码生成器
❯ k htpasswd create aaa-basic-auth user1=user1password user2=user2password -o yaml --dry-run
apiVersion: v1
data:
auth: dXNlcjE6JDJhJDEwJDVNeEJGT3lEUEJYT0xkUldlblNWME91RGtZTzFQOElJNXJuRnh5blpUdC55L2FUUUNDYzJ1CnVzZXIyOiQyYSQxMCRVbFdHOG5NTU4zRGVpOC5GMmVRM3EuYWhxTENYZGtLYUJ1cXZzT3lEOGl0ODJRdU4zV1c1dQ==
kind: Secret
metadata:
creationTimestamp: null
name: aaa-basic-auth
namespace: default
type: Opaque
该插件在为服务创建基础认证的 Ingress 很方便。
代码：
https://github.com/chenjiandongx/kubectl-images
安装： krew install images
images 现实名字空间中使用的容器镜像信息
❯ k images
[Summary]: 1 namespaces, 2 pods, 2 containers and 1 different images
+------------------------+---------------+-------------------+
| PodName | ContainerName | ContainerImage |
+------------------------+---------------+-------------------+
| webapp-98f7444c5-8772w | nginx | nginx:1.21-alpine |
+------------------------+ + +
| webapp-98f7444c5-vsxr9 | | |
+------------------------+---------------+-------------------+
代码：
https://github.com/vladimirvivien/ktop
安装： krew install ktop
ktop 插件是以类似 Linux Top 工具的方式来查询k8s集群的负载情况
❯ k ktop
┌ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
│ API server: https://k8sc1.mengz.lan:6443 Version: v1.23.8 context: admin@homek8sc1 User: kubernetes-admin namespace: (all) metrics: not connected v0.3.0
└ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
╔ Cluster Summary ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═
║ ptime: 13d Nodes: 3 Namespaces: 4 Pods: 15/15 (20 imgs) Deployments: 5/5 Sets: replicas 5, daemons 6, stateful 0 Jobs: 0 (cron: 0) PVs: 0 (0Gi) PVCs: 0 (0Gi)
║ PU: [||||||||||| ] 1600m/6000m (26.7% requested) Memory: [|| ] 1Gi/11Gi (2.5% requested)
╚ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═ ═
┌ Nodes (3) ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
│ NAME STATUS AGE VERSION INT/EXT IPs OS/ARC PODS/IMGs DISK CPU MEM
│ homek8sc1-control Ready 13d v1.23.8 192.168.0.140/<none> Ubuntu 20.04.4 LTS/amd64 9/10 16Gi [|||||| ] 1100m/2000m (55%) [|| ] 1Gi/2Gi (13%)
│ homek8sc1-worker1 Ready 13d v1.23.8 192.168.0.141/<none> Ubuntu 20.04.4 LTS/amd64 3/5 16Gi [|| ] 250m/2000m (12%) [ ] 0Gi/5Gi (0%)
│ homek8sc1-worker2 Ready 13d v1.23.8 192.168.0.142/<none> Ubuntu 20.04.4 LTS/amd64 3/5 16Gi [|| ] 250m/2000m (12%) [ ] 0Gi/5Gi (0%)
│
└ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
┌ Pods (15) ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
│ AMESPACE POD READY STATUS RESTARTS AGE VOLS IP NODE CPU MEMORY
│ ube-system kube-controller-manager-homek8sc1-control 1/1 Running 1 13d 8/8 192.168.0.140 homek8sc1-control [| ] 200m 10.0% [ ] 0Gi 0.0%
│ ube-system kube-proxy-4c9nq 1/1 Running 2 13d 4/4 192.168.0.141 homek8sc1-worker1 [ ] 0m 0.0% [ ] 0Gi 0.0%
│ ube-system kube-proxy-4whcn 1/1 Running 1 13d 4/4 192.168.0.140 homek8sc1-control [ ] 0m 0.0% [ ] 0Gi 0.0%
│ ube-system kube-proxy-bz8lt 1/1 Running 3 13d 4/4 192.168.0.142 homek8sc1-worker2 [ ] 0m 0.0% [ ] 0Gi 0.0%
│ ube-system kube-scheduler-homek8sc1-control 1/1 Running 1 13d 1/1 192.168.0.140 homek8sc1-control [| ] 100m 5.0% [ ] 0Gi 0.0%
└ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
krew-index 里包含了大量功能强大的扩展插件，涵盖了 RBAC 管理，资源管理等功能，这里没法一一列出。不过有了 krew ，我们可以很方便地安装需要的扩展，以在日常工作中提高我们管理k8s集群的的生产力。
参考
https://kubernetes.io/docs/tasks/extend-kubectl/kubectl-plugins/
https://krew.sigs.k8s.io/docs/user-guide/quickstart/
