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我在 Kubernetes 中部署了一个 MongoDB ReplicaSet 作为 StatefulSet。我正在运行一个 Bare Metal K8S 集群，因此我使用 MetalLB 来公开 LoadBalancer 类型的服务。如果我的 MongoDB-RS 设置暴露服务如下所示：

NAME              TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)           AGE
mongo-0           LoadBalancer   10.43.199.127   172.16.24.151   27017:31118/TCP   55m
mongo-1           LoadBalancer   10.43.180.131   172.16.24.152   27017:31809/TCP   55m
mongo-2           LoadBalancer   10.43.156.124   172.16.24.153   27017:30312/TCP   55m

这可以按预期工作，但是从外部客户端连接到 RS 时出现问题：

➜  ~ mongo "mongodb://172.16.24.151:27017,172.16.24.152:27017,172.16.24.153:27017/?replicaSet=rs0"
MongoDB shell version v4.0.10
connecting to: mongodb://172.16.24.151:27017,172.16.24.152:27017,172.16.24.153:27017/?gssapiServiceName=mongodb&replicaSet=rs0
2019-07-05T10:47:27.058+0200 I NETWORK  [js] Starting new replica set monitor for rs0/172.16.24.151:27017,172.16.24.152:27017,172.16.24.153:27017
2019-07-05T10:47:27.106+0200 I NETWORK  [js] Successfully connected to 172.16.24.153:27017 (1 connections now open to 172.16.24.153:27017 with a 5 second timeout)
2019-07-05T10:47:27.106+0200 I NETWORK  [ReplicaSetMonitor-TaskExecutor] Successfully connected to 172.16.24.151:27017 (1 connections now open to 172.16.24.151:27017 with a 5 second timeout)
2019-07-05T10:47:27.136+0200 I NETWORK  [ReplicaSetMonitor-TaskExecutor] changing hosts to rs0/10.42.2.155:27017,10.42.3.147:27017,10.42.4.108:27017 from rs0/172.16.24.151:27017,172.16.24.152:27017,172.16.24.153:27017
2019-07-05T10:47:52.654+0200 W NETWORK  [js] Unable to reach primary for set rs0
2019-07-05T10:47:52.654+0200 I NETWORK  [js] Cannot reach any nodes for set rs0. Please check network connectivity and the status of the set. This has happened for 1 checks in a row.
2019-07-05T10:47:52.654+0200 E QUERY    [js] Error: connect failed to replica set rs0/172.16.24.151:27017,172.16.24.152:27017,172.16.24.153:27017 :
connect@src/mongo/shell/mongo.js:344:17

在某些时候它说“将主机更改为 rs0/10.42.2.155:27017,10.42.3.147:27017,10.42.4.108:27017”。由于这些 IP 是集群内部的，因此在此之后连接将失败。

有什么建议我能做什么？

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You are using a LoadBalancer that is not stiky session on it, you can use an nginx controller to provide loadbalancer based on nginx with the ability to set sticky session affinity based on client or cookie.

https://github.com/kubernetes/ingress-nginx

Another option is to use a different container as a mongo proxy, for example you can use HAPoxy container where you config HAProxy to listen to TCP connections on 27017 port and as backends the 3 different mongo services, remain that you need to setup a healtheck in HAProxy to allow the process of knowing how many of the backens are alive.

于 2019-07-05T10:25:48.220 回答