当用户在云容器引擎中拥有多个Kubernetes（K8s）集群实例时，如何在一个主机终端通过kubectl连接访问多个集群，请参考如下指引。

前提条件：

拥有多个集群实例，且当前用户在某一主机网络能够连接多个集群的主机。

原理：

在某一主机上，配置多个集群实例的kubectl访问凭证，通过kubectl命令切换使用不同集群的上下文。

获取多个集群的kubectl访问凭证：

打开云容器引擎的集群信息-连接信息tab页面，可查看到当前集群的访问凭证，点击复制按钮：

apiVersion: v1
clusters:
- cluster:
    server: https://xxx.xxx.xxx.xxx:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: "16261"
  name: 16261-17120288662000021
current-context: 16262-17120288662000021
kind: Config
preferences: {}
users:
- name: "16261"
  user:
    client-certificate-data: LS0tLS1CRUdJTiBDR1...
    client-key-data: LS0tLS1CRUdJTiBSU0Eg1...

• clusters：描述集群的信息，我们需要取集群的访问地址，用于配置多个集群cluster列表。
• users：描述访问集群访问用户的信息，我们需要取client-certificate-data和client-key-data这两个证书文件内容，用于配置多个集群的user列表。
• contexts：描述集群配置的上下文，每个上下文关联了user和对应的cluster，用kubectl命令切换上下文，便可指定使用指定的user去访问对应的集群。

注意
一个集群可能有内网访问地址和公网访问地址，有两个上下文，可配置成两个cluster及对应的usercontext，通过切换上下文选择使用不同的地址访问集群。

配置多个集群的kubectl访问凭证

下面用2个集群为例演示如何修改config文件访问多个集群。

• 获取集群A的访问凭证，例如：

  apiVersion: v1
  clusters:
  - cluster:
      server: https://xxx.xxx.xxx.xx1:6443
    name: kubernetes
  contexts:
  - context:
      cluster: kubernetes
      user: "16261"
    name: 16261-17120288662000021
  current-context: 16261-17120288662000021
  kind: Config
  preferences: {}
  users:
  - name: "16261"
    user:
      client-certificate-data: LS0tLS1CRUdJTiBDR1...
      client-key-data: LS0tLS1CRUdJTiBSU0Eg1...
  

• 把集群cluster名、用户user名修改成方便识别的名称，例如集群名修改成cluster-a，用户名修改成cluster-a-user：

  apiVersion: v1
  clusters:
  - cluster:
      server: https://xxx.xxx.xxx.xx1:6443
    name: cluster-a
  contexts:
  - context:
      cluster: cluster-a
      user: "cluster-a-user"
    name: cluster-a-context
  current-context: cluster-a-context
  kind: Config
  preferences: {}
  users:
  - name: "cluster-a-user"
    user:
      client-certificate-data: LS0tLS1CRUdJTiBDR1...
      client-key-data: LS0tLS1CRUdJTiBSU0Eg1...
  

• 获取集群B的访问凭证，例如：

  apiVersion: v1
  clusters:
  - cluster:
      server: https://xxx.xxx.xxx.xx2:6443
    name: kubernetes
  contexts:
  - context:
      cluster: kubernetes
      user: "16262"
    name: 16262-17120288662000022
  current-context: 16262-17120288662000022
  kind: Config
  preferences: {}
  users:
  - name: "16262"
    user:
      client-certificate-data: LS0tLS1CRUdJTiBDR2...
      client-key-data: LS0tLS1CRUdJTiBSU0Eg2...
  

• 把集群cluster名、用户user名修改成方便识别的名称，例如集群名修改成cluster-b，用户名修改成cluster-b-user：

  apiVersion: v1
  clusters:
  - cluster:
      server: https://xxx.xxx.xxx.xx2:6443
    name: cluster-b
  contexts:
  - context:
      cluster: cluster-b
      user: "cluster-b-user"
    name: cluster-b-context
  current-context: cluster-b-context
  kind: Config
  preferences: {}
  users:
  - name: "cluster-b-user"
    user:
      client-certificate-data: LS0tLS1CRUdJTiBDR2...
      client-key-data: LS0tLS1CRUdJTiBSU0Eg2...
  

• 把两份凭证合并到同个config文件，把两份文件中的cluster、user、contenxt合并到同一父路径下：

  apiVersion: v1
  clusters:
  - cluster:
      server: https://xxx.xxx.xxx.xx1:6443
    name: cluster-a
  - cluster:
      server: https://xxx.xxx.xxx.xx2:6443
    name: cluster-b
  contexts:
  - context:
      cluster: cluster-a
      user: "cluster-a-user"
    name: cluster-a-context
  - context:
      cluster: cluster-b
      user: "cluster-b-user"
    name: cluster-b-context
  current-context: cluster-a-context
  kind: Config
  preferences: {}
  users:
  - name: "cluster-a-user"
    user:
      client-certificate-data: LS0tLS1CRUdJTiBDR1...
      client-key-data: LS0tLS1CRUdJTiBSU0Eg1...
  - name: "cluster-b-user"
    user:
      client-certificate-data: LS0tLS1CRUdJTiBDR2...
      client-key-data: LS0tLS1CRUdJTiBSU0Eg2...
  

使用配置凭证

• 把上述config文件配置到home的下面目录：

  [docker@10 ~]$ mkdir -p $HOME/.kube
  [docker@10 ~]$ mv config $HOME/.kube
  

• 使用kubectl命令切换集群上下文：

  [docker@10 ~]$ kubectl config use-context cluster-a-context
  Switched to context "cluster-a-context".
  [docker@10 ~]$ kubectl cluster-info
  Kubernetes master is running at https://xxx.xxx.xxx.97:6443
  KubeDNS is running at https://xxx.xxx.xxx.97:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
  
  To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
  [docker@10 ~]$ kubectl config use-context cluster-b-context
  Switched to context "cluster-b-context".
  [docker@10 ~]$ kubectl cluster-info
  Kubernetes master is running at https://xxx.xxx.xxx.46:6443
  CoreDNS is running at https://xxx.xxx.xxx.46:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
  
  To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.