I'm trying to add a second network interface in Docker containers (with only Docker, I simply add my container to another "docker network" using the docker network command) in Kubernetes such that containers are also able to communicate together through this second interface.

The thing is that it is not possible to simply call the docker network command. I get the following error: Container sharing network namespace with another container or host cannot be connected to any other network.

This error seems logic to me as the network is not managed the same way with Kubernetes (all containers in a pod share their IP if I understood correctly). But now the question is: how can I add a second network interface easily to my container (or to my pod)?

I did some research and I found that Kubernetes is able to use CNI and that it could be my solution. But I was unable to have it working (don't know if the error is on my side or because everything is continuously evolving). I also searched for other solutions in the Kubernetes documentation, but I don't know if one of them can make me happy in an easy way :)

Thanks for your help!

P.S.: For a bit more context, I am creating containers with an application that needs to have two working interfaces (I cannot modify this application to use only one NIC) and I'm trying to have it working on my laptop (local Kubernetes/Docker installation) without needing replication on multiple nodes.