Kubernetes pod 应用程序与不在容器上的 Mysql 数据库的连接

Question

can i connect k8's POD with non container application,where my kubernetes POD is running on 10.200.xx subnet and my mysql is running on simple linux server other than container how can i connect with the database? As im working in a organization where there are so many network restrictions and i have to open ports and IPs to access do i have possibility to connect container application with non container database as subnet masks are different too

Answer 1

If you can reach mysql from worker node then you should also be able to reach it from pod running on this node.

Check you company firewall and make sure that packets from worker node can reach the instance with mysql running. Also make sure that these networks are not separated in some other way.

Usually packets sent from your application pod to mysql instance will have source ip set to worker nodes ip (so you want to allow for traffic from k8s nodes to mysql instance). This is due to fact that k8s network (with most CNIs) is sort of a virtual network that only k8s nodes aware of and for external traffic to by able to come back to the pod, routers in your network need to know where to route the traffic to. This is why pod traffic going outside of k8s network is NATed.

This is true for most CNIs that encapsulate internal traffic in k8s but remeber that there are also some CNIs that don't encapsulate traffic and it makes possible to access pods directly from anywhere inside of a private network and not only from k8s nodes (eg Azure CNI).

In first case with NATed network make sure that you enable access to mysql instance from all worker nodes, not just one because when this one specific node goes down and pod gets rescheduled to other node it wont be able to connect to the database.

In second case where you are using CNI that is using direct netwoking (without NAT) its more complicated because when pod gets rescheduled it gets different ip every time and I can't help you with that as it all depends on specific CNI.