kubectl plugin插件机制初体验之krew

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kubectl plugin插件机制初体验之krew 2019-04-09 次阅读文章目录

【注意】最后更新于 April 9, 2019，文中内容可能已过时，请谨慎使用。

1.kubectl插件机制简介

kubectl插件机制在Kubernetes 1.14宣布稳定，进入GA状态。kubectl的插件机制就是希望允许开发者以独立的二进制形式发布自定义的kubectl子命令。

kubectl插件可以使用任意语言开发，如可以是一个bash、python的脚本，也可以是其他语言开发编译的二进制可执行文件，只要最终将脚本或二进制可执行文件以kubectl-的前缀放到PATH中即可。使用kubectl plugin list可以在PATH中查看有哪些插件。

1 2 3 kubectl plugin list error: unable to find any kubectl plugins in your PATH

Kubernetes提供了一个https://github.com/kubernetes/cli-runtime项目，便于我们使用Go语言编写kubectl插件。官方也给了一个使用Go编写kubectl插件的例子https://github.com/kubernetes/sample-cli-plugin。

2.kubectl插件的包管理工具krew

krew是kubectl插件的管理器，使用krew可以轻松的查找、安装和管理kubectl插件。krew自己也作为一个kubectl插件存在。

2.1 安装krew

确认目标机器上已经安装了git，krew在更新本地插件索引时会用到git。

在kubernetes的管理节点上：

1 2 3 4 wget https://storage.googleapis.com/krew/v0.2.1/krew.tar.gz wget https://storage.googleapis.com/krew/v0.2.1/krew.yaml tar -zxvf krew.tar.gz 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 ./krew-linux_amd64 install --manifest=krew.yaml --archive=krew.tar.gz Installing plugin: krew CAVEATS: \ | krew is now installed! To start using kubectl plugins, you need to add | krew's installation directory to your PATH: | | * macOS/Linux: | - Add the following to your ~/.bashrc or ~/.zshrc: | export PATH="${KREW_ROOT:-$HOME/.krew}/bin:$PATH" | - Restart your shell. | | * Windows: Add %USERPROFILE%\.krew\bin to your PATH environment variable | | Run "kubectl krew" to list krew commands and get help. | You can find documentation at https://github.com/GoogleContainerTools/krew. / Installed plugin: krew ls ~/.krew/bin/ kubectl-krew

可以看到可执行文件kubectl-krew被安装到了$HOME/.krew/bin路径下。接下来将$HOME/.krew/bin加入到PATH环境变量中。

再次查看当前可用的kubectl plugin，发现多了一个kubect-krew:

1 2 3 4 kubectl plugin list The following compatible plugins are available: /root/.krew/bin/kubectl-krew 2.2 使用krew

kubectl krew命令的帮助信息如下：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 kubectl krew krew is the kubectl plugin manager. You can invoke krew through kubectl: "kubectl krew [command]..." Usage: krew [command] Available Commands: help Help about any command info Show information about a kubectl plugin install Install kubectl plugins list List installed plugins remove Uninstall plugins search Discover kubectl plugins update Update the local copy of the plugin index upgrade Upgrade installed plugins to newer versions version Show krew version and diagnostics Flags: -h, --help help for krew -v, --v Level log level for V logs Use "krew [command] --help" for more information about a command.

更新本地插件索引：

1 2 kubectl krew update Updated the local copy of plugin index.

查看所有可用插件：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 kubectl krew search NAME DESCRIPTION STATUS access-matrix Show an access matrix for all resources available bulk-action Do bulk actions on Kubernetes resources. available ca-cert Print the PEM CA certificate of the current clu... available change-ns View or change the current namespace via kubectl. available cssh SSH into Kubernetes nodes available debug-shell Create pod with interactive kube-shell. available exec-as Like kubectl exec, but offers a `user` flag to ... available get-all Like 'kubectl get all', but _really_ everything available gke-credentials Fetch credentials for GKE clusters available ingress-nginx Interact with ingress-nginx available krew Package manager for kubectl plugins. installed kubesec-scan Scan Kubernetes resources with kubesec.io. available match-name Match names of pods and other API objects available mtail Tail logs from multiple pods matching label sel... available node-admin List nodes and run privileged pod with chroot available oidc-login Login for OpenID Connect authentication available open-svc Open the Kubernetes URL(s) for the specified se... available pod-logs Display a list of pods to get logs from available pod-shell Display a list of pods to execute a shell in available prompt Prompts for user confirmation when executing co... available rbac-lookup Reverse lookup for RBAC available rbac-view A tool to visualize your RBAC permissions. available resource-capacity Provides an overview of resource requests, limi... available restart Restarts a pod with the given name available rm-standalone-pods Remove all pods without owner references available sniff easly start a remote packet capture on kubernet... available ssh-jump A kubectl plugin to SSH into Kubernetes nodes u... available sudo Run Kubernetes commands impersonated as group s... available view-secret Decode secrets available view-serviceaccount-kubeconfig Show a kubeconfig setting to access the apiserv... available view-utilization Shows cluster cpu and memory utilization available warp Sync and execute local files in Pod available

下面体验安装一下change-ns这个kubectl plugin：

1 2 3 4 5 6 7 8 kubectl krew install change-ns Updated the local copy of plugin index. Installing plugin: change-ns CAVEATS: \ | This plugin requires an existing KUBECONFIG file, with a `current-context` field set. / Installed plugin: change-ns 1 2 3 4 5 6 7 8 kubectl change-ns ingress-nginx namespace changed to "ingress-nginx" kubectl get pod NAME READY STATUS RESTARTS AGE nginx-ingress-controller-575d546f7c-jsvhv 1/1 Running 2 44h nginx-ingress-default-backend-7c5fb8d8f4-ncskr 1/1 Running 2 2d

这里体验安装了https://github.com/juanvallejo/kubectl-ns。

参考 Extend kubectl with plugins kubernetes-sigs/krew

文章作者青蛙小白

上次更新 2019-04-09

Kubernetes

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