mirror of https://github.com/easzlab/kubeasz.git
108 lines
5.8 KiB
Markdown
108 lines
5.8 KiB
Markdown
# 更改高可用 `Master IP`
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**WARNING:** 更改集群的 `Master VIP`操作有风险，不建议在生产环境直接操作，此文档实践一个修改的操作流程，帮助理解整个集群运行架构和 `kubeasz`的部署逻辑，请在测试环境操作练手。
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**BUG:** 目前该操作只适用于集群网络选用`calico`，如果使用`flannel`操作变更后会出现POD地址分配错误的BUG。
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首先分析大概操作思路：
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- 修改`/etc/ansible/hosts`里面的配置项`MASTER_IP` `KUBE_APISERVER`
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- 修改LB节点的keepalive的配置，重启keepalived服务
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- 修改kubectl/kube-proxy的配置文件，使用新VIP地址更新api-server地址
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- 重新生成master证书，hosts字段包含新VIP地址
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- 修改kubelet的配置文件（kubelet的配置文件和证书是由bootstrap机制自动生成的）
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- 删除kubelet.kubeconfig
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- 删除集群所有node 节点
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- 所有节点重新bootstrap
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## 变更前状态验证
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``` bash
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$ kubectl get cs,node,pod -o wide
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NAME STATUS MESSAGE ERROR
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controller-manager Healthy ok
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scheduler Healthy ok
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etcd-2 Healthy {"health":"true"}
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etcd-0 Healthy {"health":"true"}
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etcd-1 Healthy {"health":"true"}
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NAME STATUS ROLES AGE VERSION EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
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192.168.1.41 Ready,SchedulingDisabled <none> 2h v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-97-generic docker://18.3.0
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192.168.1.42 Ready,SchedulingDisabled <none> 2h v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-97-generic docker://18.3.0
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192.168.1.43 Ready <none> 2h v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-97-generic docker://18.3.0
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192.168.1.44 Ready <none> 2h v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-98-generic docker://18.3.0
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192.168.1.45 Ready <none> 2h v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-98-generic docker://18.3.0
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NAME READY STATUS RESTARTS AGE IP NODE
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busy-5d6b6b5d4b-8wxkp 1/1 Running 0 17h 172.20.135.133 192.168.1.41
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busy-5d6b6b5d4b-fcmkp 1/1 Running 0 17h 172.20.135.128 192.168.1.41
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busy-5d6b6b5d4b-ptvd7 1/1 Running 0 17h 172.20.135.136 192.168.1.41
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nginx-768979984b-ncqbp 1/1 Running 0 17h 172.20.135.137 192.168.1.41
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# 查看待变更集群 Master VIP
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$ kubectl cluster-info
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Kubernetes master is running at https://192.168.1.39:8443
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```
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## 变更操作
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- `ansible playbook`可以使用tags来控制只允许部分任务执行，这里为简化操作没有细化，在ansible控制端具体操作如下：
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``` bash
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# 1.修改/etc/ansible/hosts 配置项MASTER_IP，KUBE_APISERVER
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# 2.删除集群所有node节点，等待重新bootstrap
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$ kubectl get node |grep Ready|awk '{print $1}' |xargs kubectl delete node
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# 3.重置keepalived 和修改kubectl/kube-proxy/bootstrap配置
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$ ansible-playbook 01.prepare.yml
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# 4.删除旧master证书
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$ ansible kube-master -m file -a 'path=/etc/kubernetes/ssl/kubernetes.pem state=absent'
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# 5.删除旧kubelet配置文件
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$ ansible all -m file -a 'path=/etc/kubernetes/kubelet.kubeconfig state=absent'
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# 6.重新配置启动master节点
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$ ansible-playbook 04.kube-master.yml
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# 7.重新配置启动node节点
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$ ansible-playbook 05.kube-node.yml
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```
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## 变更后验证
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``` bash
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$ kubectl get cs,node,pod -o wide
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NAME STATUS MESSAGE ERROR
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scheduler Healthy ok
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controller-manager Healthy ok
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etcd-2 Healthy {"health":"true"}
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etcd-1 Healthy {"health":"true"}
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etcd-0 Healthy {"health":"true"}
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NAME STATUS ROLES AGE VERSION EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
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192.168.1.41 Ready,SchedulingDisabled <none> 4m v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-97-generic docker://18.3.0
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192.168.1.42 Ready,SchedulingDisabled <none> 4m v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-97-generic docker://18.3.0
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192.168.1.43 Ready <none> 3m v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-97-generic docker://18.3.0
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192.168.1.44 Ready <none> 3m v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-98-generic docker://18.3.0
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192.168.1.45 Ready <none> 3m v1.10.0 <none> Ubuntu 16.04.3 LTS 4.4.0-98-generic docker://18.3.0
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NAME READY STATUS RESTARTS AGE IP NODE
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busy-5d6b6b5d4b-25hfr 1/1 Running 0 5m 172.20.237.64 192.168.1.43
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busy-5d6b6b5d4b-cdzb5 1/1 Running 0 5m 172.20.145.192 192.168.1.44
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busy-5d6b6b5d4b-m2rf7 1/1 Running 0 5m 172.20.26.131 192.168.1.45
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nginx-768979984b-2ngww 1/1 Running 0 5m 172.20.145.193 192.168.1.44
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# 查看集群master VIP已经变更
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$ kubectl cluster-info
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Kubernetes master is running at https://192.168.1.40:8443
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```
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## 小结
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本示例操作演示了多主多节点k8s集群变更`Master VIP`的操作，有助于理解整个集群组件架构和`kubeasz`的安装逻辑，小结如下：
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- 变更操作不影响集群已运行的业务POD，但是操作过程中业务会中断
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- 已运行POD会重新调度到各node节点，如果业务POD量很大，短时间内会对集群造成压力
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- 不建议在生成环境直接操作，本示例演示说明为主
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