ovn-ic的gw-nodes如果网关节点出故障，无法自动切换到配置的其他节点作为网关节点，导致通信故障

[geniusxiong]

Bug Report

ovn-ic的gw-nodes，配置成2个或多个节点作为集群互联中承担网关工作，但是配置的节点故障后，不能自动切换到其他节点继续作为网关节点，导致通信故障

Expected Behavior

Actual Behavior

ovn-ic的gw-nodes中，配置好的网关节点，如果其中一个节点故障，能够自定切换到配置的其他节点作为网关节点

Steps to Reproduce the Problem

1. 配置一个节点ovn-ic-config ConfigMap:

   apiVersion: v1
   kind: ConfigMap
   metadata:
   name: ovn-ic-config
   namespace: kube-system
   data:
   enable-ic: "true"
   az-name: "az176" 
   ic-db-host: "172.18.164.171"
   ic-nb-port: "6645" 
   ic-sb-port: "6646"
   gw-nodes: "node-0,node-1"
   auto-route: "true"

2. ovn-ic 容器内已建立互联逻辑交换机 ts，集群可以互通

   root@master-1:/kube-ovn# ovn-ic-sbctl show
   availability-zone az140
   gateway b5f7b2d5-e002-486b-a933-9d30f92b09d5
       hostname: node-0
       type: geneve
           ip: 172.18.164.143
   gateway e33e7c0d-b3c3-4afd-9598-569f024aeb9e
       hostname: master-0
       type: geneve
           ip: 172.18.164.140
       port ts-az140
           transit switch: ts
           address: ["00:00:00:E3:E2:BC 169.254.100.93/24"]
   availability-zone az170
   gateway 224a129c-63ce-46fb-b94f-e87ee7bd0f52
       hostname: node-0
       type: geneve
           ip: 172.18.164.173
       port ts-az170
           transit switch: ts
           address: ["00:00:00:34:05:F3 169.254.100.80/24"]
   **availability-zone az176**
   gateway 787b7f2e-a18a-4c77-b4a1-0fcf304fbbe7
       **hostname: node-1**
       type: geneve
           ip: 172.18.164.177
       **port ts-az176**
           transit switch: ts
           address: ["00:00:00:50:E0:EB 169.254.100.90/24"]
   gateway 7e6c6ee8-5f12-4eea-b7d6-355b61297fff
       **hostname: node-0**
       type: geneve
           ip: 172.18.164.179

   此时集群互通成功，az176的pod能够访问az170和az140的pod

3. 把集群az176的node-1节点（172.18.164.177）关机，ovn-ic 容器内已建立互联逻辑交换机 ts没有变化，并没有自动切换到配置的node-0节点作为网关维持通信，此时az176的pod不能访问az170和az140的pod

4. 把集群az176的node-1节点（172.18.164.177）开机，通信恢复正常

Additional Info

• Kubernetes version:

  Output of kubectl version:

Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.6", GitCommit:"dff82dc0de47299ab66c83c626e08b245ab19037", GitTreeState:"clean", BuildDate:"2020-07-15T16:58:53Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.6", GitCommit:"dff82dc0de47299ab66c83c626e08b245ab19037", GitTreeState:"clean", BuildDate:"2020-07-15T16:51:04Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}

• kube-ovn version:

1.11.3

• operation-system/kernel version:

  Output of awk -F '=' '/PRETTY_NAME/ { print $2 }' /etc/os-release: Output of uname -r:

NFS Server 4.0 (G193)
4.19.113-3.nfs.x86_64  

[geniusxiong]

网关节点需要配置成3个以上，才可以自动切换。