Multicast traffic to Kubernetes

问题

I want my pods to receive multicast network traffic flowing from outside of my kubernetes cluster to specific ports in my nodes.

I'm considering two solutions:

1. Adding hostNetwork: true flag to their yaml file along with hostPort configuration in order to receive the traffic directly to the pod.
2. Forwarding the traffic locally on the nodes from eth0 interface to docker0 interface using iptables command.

Method 1 is an official feature in Kubernetes, but it feels like breaking a security wall that docker originally imposed, and might cause port collisions with host's processes, etc.

Method 2 on the other hand transparently forwards the multicast network traffic to the pods.
Despite the fact I can use an automation tool to spread this configuration (ansible/salt etc), anything configured 'out of the scope' of Kubernetes feels a little hacky to me.

Would like to hear your pros and cons, comments, and maybe other solutions to the problem of multicasting to a kubernetes cluster.

回答1:

In the end we picked method 1, as it is the documented way to achieve what we wanted, and I can report that it works fine.

回答2:

I played a bit with hostNetwork and I understand your reservations. I see that turning it on gives my pod the same IP as the hosting node. But then it cannot communicate with any of the nodes (maybe I did something wrong?).

Edit: I definitely missed out on something

hostNetwork: true
dnsPolicy: ClusterFirstWithHostNet

I added the dnsPolicy

So I am trying now something alternative working with a CNI. Still researching that. It is new for me, so I will post an update once I can.

回答3:

I heard that WeaveWorks supports multicast: https://www.weave.works/use-cases/multicast-networking/

来源：https://stackoverflow.com/questions/48304357/multicast-traffic-to-kubernetes