多叢集的切換是K8s運維中比不可少的問題，常見的基於多個叢集進行切換的方法有三種：

• 切換config檔案
• 通過context進行叢集切換
• 用kubecm進行叢集切換

切換config檔案

我們先看看放在.kube下預設的config叢集：

$ kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: 
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: "2xxxxxxxxx7"
  name: 2xxxxxxxxxxxxxxxx8
current-context: 2xxxxxxxxxxxx8
kind: Config
preferences: {}
users:
- name: "2xxxxxxxxxxx27"
  user:
    client-certificate-data: 
    client-key-data:
 

通過export更改預設叢集配置：

$ export  KUBECONFIG=$HOME/.kube/rancher-config

檢視：

$ kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: 
  name: stage
contexts:
- context:
    cluster: stage
    user: stage
  name: stage
current-context: stage
kind: Config
preferences: {}
users:
- name: stage
  user:
    token:
 

這種方法就是特別麻煩，每次切換都要通過export設定，非常麻煩，同時也不方便。

通過context進行叢集切換

把要切換的所有config檔案新增到KUBECONFIG環境變數中

$ export  KUBECONFIG=$HOME/.kube/config:$HOME/.kube/rancher-config

或者可以將命令直接寫到.bashrc檔案中，這樣就不需要每次手動設定。

通過kubectl config view可以看到這兩個檔案已經合併到一起了：

$ kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: 
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: "2xxxxxxxxx7"
  name: 2xxxxxxxxxxxxxxxx8
current-context: 2xxxxxxxxxxxx8
kind: Config
preferences: {}
users:
- name: "2xxxxxxxxxxx27"
  user:
    client-certificate-data: 
    client-key-data:
 

合併一起後就可以通過use-context切換上下文來切換叢集：

# 切換stage叢集
$ kubectl config use-context stage
Switched to context "stage".

切換到第二個叢集：

$ kubectl config use-context 2xxxxxxxxxxx8
Switched to context "21xxxxxxxxxxxxx9648".

但這種方法不方便的地方就在如果context很多的時候，不方便檢視。

用kubecm進行叢集切換

安裝篇

基礎環境

mac

k8s 1.16.9

# wget https://github.com.cnpmjs.org/sunny0826/kubecm/releases/download/v0.10.3/kubecm_0.10.3_Darwin_x86_64.tar.gz
# tar xf kubecm_0.10.3_Darwin_x86_64.tar.gz
# mv kubecm /usr/local/bin
# kubecm --help

KubeConfig Manager
_          _
| | ___   _| |__   ___  ___ _ __ ___
| |/ / | | | '_ \ / _ \/ __| '_ \ _ \
|   <| |_| | |_) |  __/ (__| | | | | |
|_|\_\\__,_|_.__/ \___|\___|_| |_| |_|

Find more information at: https://github.com/sunny0826/kubecm

Usage:
kubecm [command]

Available Commands:
add         Merge configuration file with $HOME/.kube/config
alias       Generate alias for all contexts
completion  Generates bash/zsh completion scripts
delete      Delete the specified context from the kubeconfig
help        Help about any command
ls          List kubeconfig
merge       Merge the kubeconfig files in the specified directory
namespace   Switch or change namespace interactively
rename      Rename the contexts of kubeconfig
switch      Switch Kube Context interactively
version     Print version info

Flags:
    --config string   path of kubeconfig (default "/var/root/.kube/config")
-h, --help            help for kubecm

Use "kubecm [command] --help" for more information about a command.

補全

bash

# ource <(kubecm completion bash)
# echo "source <(kubecm completion bash)" >> ~/.bashrc
# source  ~/.bashrc

zsh

# source <(kubecm completion zsh)
# echo "source <(kubecm completion zsh)" >> ~/.zshrc
# source  ~/.zshrc

基本使用

檢視

# kubecm ls
+------------+-----------------------------------+---------------+-----------------------+--------------------------------+--------------+
|   CURRENT  |                NAME               |    CLUSTER    |          USER         |             SERVER             |   Namespace  |
+============+===================================+===============+=======================+================================+==============+
|      *     |   283387751775489594-c02e82b6ada  |   kubernetes  |   283387751775489594  |   https://3.3.3.3:6443  |    default   |
|            |       f044bd94d251fea1279648      |               |                       |                                |              |
+------------+-----------------------------------+---------------+-----------------------+--------------------------------+--------------+

Cluster check succeeded!
Kubernetes master is running at https://3.3.3.3:6443
Contains components: [scheduler controller-manager etcd-5 etcd-0 etcd-4 etcd-1 etcd-3 etcd-2]

新增

# ll
-rw-r--r--    1 root  wheel   5.9K  8 26 15:39 config.shengchan
-rw-r--r--    1 root  wheel   5.9K 11 18 15:59 config.yufa

# kubecm add -f config.yufa -c -n stage
# kubecm add -f config.shengchan -c -n production
#  kubecm ls
+------------+---------------+-----------------------+--------------------+--------------------------------+--------------+
|   CURRENT  |      NAME     |        CLUSTER        |        USER        |             SERVER             |   Namespace  |
+============+===============+=======================+====================+================================+==============+
|      *     |   production  |   cluster-kg7h48f8tb  |   user-kg7h48f8tb  |   https://3.3.3.3:6443  |    default   |
+------------+---------------+-----------------------+--------------------+--------------------------------+--------------+
|            |     stage     |   cluster-kfc6fbfcdt  |   user-kfc6fbfcdt  |   https://4.4.4.4:6443  |    default   |
+------------+---------------+-----------------------+--------------------+--------------------------------+--------------+

刪除

# kubecm delete