1. 前提
在实际生产环境中，往往需要维护多个k8s集群，在多个环境和节点之间切换，影响工作效率，不符合devops的理念，因此作者尝试在单个节点下面维护多个k8s集群。
2. 要求
- 了解k8s的context
- 了解k8s的kubeconfig
- 至少2个以上k8s集群
3. 实验
3.1 k8s集群
- 节点t34集群
[root@t34 ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
t31 Ready worker 156d v1.14.3
t32 Ready worker 70d v1.14.3
t34 Ready controlplane,etcd,worker 199d v1.14.3
t90 Ready worker 156d v1.14.3
t91 Ready worker 169d v1.14.3
- 节点node43集群
[root@node43 ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
node43 Ready controlplane,etcd,worker 121d v1.14.3
3.2 kubeconfig文件
查看kubeconfig文件可以使用kubectl命令,也可以直接查看/root/.kube/config（默认位置）
- node43集群
[root@node43 ~]# kubectl config view
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: DATA+OMITTED
server: https://192.168.5.43/k8s/clusters/c-mg6wm
name: test
- cluster:
certificate-authority-data: DATA+OMITTED
server: https://192.168.5.43:6443
name: test-node43
contexts:
- context:
cluster: test
user: user-twwt4
name: test
- context:
cluster: test-node43
user: user-twwt4
name: test-node43
current-context: test
kind: Config
preferences: {}
users:
- name: user-twwt4
user:
token: kubeconfig-user-twwt4.c-mg6wm:r7bk54gw2h5vpx6wqwbqrldzhp2nz5lppvf5cfgbgnwffsj7rfkjdp
- t34集群
[root@t34 canary]# kubectl config view
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: DATA+OMITTED
server: https://192.168.4.34/k8s/clusters/c-6qgsl
name: test
- cluster:
certificate-authority-data: DATA+OMITTED
server: https://192.168.4.34:6443
name: test-t34
contexts:
- context:
cluster: test
user: user-czbv6
name: test
- context:
cluster: test-t34
user: user-czbv6
name: test-t34
current-context: test
kind: Config
preferences: {}
users:
- name: user-czbv6
user:
token: kubeconfig-user-czbv6.c-6qgsl:tznvpqkdw7mz6r8276h8zs5hbl45h2bv2g8jwfjqc8qckhgfwwz9rd
3.3 配置
在t34上面配置node43的cluster,user以及context
- 添加cluster
[root@t34 canary]# kubectl config set-cluster node43 --server=https://192.168.5.43:6443 --insecure-skip-tls-verify=true
Cluster "node43" set.
- 添加user
[root@t34 canary]# kubectl config set-credentials node43-user --token=kubeconfig-user-twwt4.c-mg6wm:r7bk54gw2h5vpx6wqwbqrldzhp2nz5lppvf5cfgbgnwffsj7rfkjdp
User "node43-user" set.
- 添加context
[root@t34 canary]# kubectl config set-context node43-context --cluster=node43 --user=node43-user
Context "node43-context" created.
- 查看
[root@t34 canary]# kubectl config view
apiVersion: v1
clusters:
- cluster:
insecure-skip-tls-verify: true
server: https://192.168.5.43:6443
name: node43
- cluster:
certificate-authority-data: DATA+OMITTED
server: https://192.168.4.34/k8s/clusters/c-6qgsl
name: test
- cluster:
certificate-authority-data: DATA+OMITTED
server: https://192.168.4.34:6443
name: test-t34
contexts:
- context:
cluster: node43
user: node43-user
name: node43-context
- context:
cluster: test
user: user-czbv6
name: test
- context:
cluster: test-t34
user: user-czbv6
name: test-t34
current-context: test
kind: Config
preferences: {}
users:
- name: node43-user
user:
token: kubeconfig-user-twwt4.c-mg6wm:r7bk54gw2h5vpx6wqwbqrldzhp2nz5lppvf5cfgbgnwffsj7rfkjdp
- name: user-czbv6
user:
token: kubeconfig-user-czbv6.c-6qgsl:tznvpqkdw7mz6r8276h8zs5hbl45h2bv2g8jwfjqc8qckhgfwwz9rd
3.4 测试
当前context为test,cluster对应的test(即t34集群),user为user-czbv6
[root@t34 canary]# kubectl config current-context
test
[root@t34 canary]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
t31 Ready worker 156d v1.14.3
t32 Ready worker 70d v1.14.3
t34 Ready controlplane,etcd,worker 199d v1.14.3
t90 Ready worker 156d v1.14.3
t91 Ready worker 169d v1.14.3
切换context为node43-context,cluster对应的node43(即node43集群),user为node43-user
[root@t34 canary]# kubectl config use-context node43-context
Switched to context "node43-context".
[root@t34 canary]# kubectl config current-context
node43-context
[root@t34 canary]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
node43 Ready controlplane,etcd,worker 121d v1.14.3
至此，在t34节点上维护了两个k8s集群，按照同样的办法可以添加更多的k8s集群，只是通过不同的context进行切换。
btw:在同一集群下，利用context可以完成生产环境和开发环境的分离
