LAN discoverability when running in Kubernetes

[LMSSonos]

I'm running minecraft-server on kubernetes (k3s).

- image: ghcr.io/itzg/minecraft-server:latest
  name: minecraft-java-server
  env:
    - name: EULA
      value: "TRUE"
    - name: TYPE
      value: "PAPER"
    - name: PLUGINS
      value: |
        https://download.geysermc.org/v2/projects/geyser/versions/latest/builds/latest/downloads/spigot
        https://download.geysermc.org/v2/projects/floodgate/versions/latest/builds/latest/downloads/spigot

• Direct connect via Bedrock + Java from the PC works
• Direct connect from Xbox using the BCMain friend "hack" ;-) works

Neither in Bedrock (PC+Xbox) nor in Java the server is automatically discovered. I assume it has to do that the IP in the container is a different one than the the on from the kubernetes Loadbalancer. Using direct connect is not an issue on PC, but on the Xbox it would be very nice if it can be automatically discovered

I'm wondering if there is any way to solve this issue?

Thanks

[itzg]

I assume it has to do that the IP in the container is a different one than the the on from the kubernetes Loadbalancer.

I believe you're quite right with that theory. I seem to remember that the LAN discovery is quite sensitive about the reported IP address vs the client connecting IP address.

[LMSSonos]

Thanks for fast reply, in this case it would require a change by geysermc - itzg/docker-minecraft-bedrock-server#504 sounds like the same issue

[LMSSonos]

@itzg just to let you know, I did some further debugging using tcpdump. The flow is that the bedrock client makes a UDP broadcasts. Then the server (in this case GeyserMC) replies to that.

Problem is, that UDP broadcasts are not forwarded into the PODs, except when using hostNetwork: true - seems to be by design. I checked your https://github.com/itzg/minecraft-server-charts and did not find any workaround. The ENABLE_LAN_VISIBILITY has nothing to do with this, right?

[itzg]

Unfortunately, no, that environment variable doesn't relate to that directly. Just maps to the property within bedrock itself.

As is, the chart variable minecraftServer.serviceType being set to NodePort is the closest you could get. The mismatch in ports could be a problem though since I think the advertised needs to match the client used.

I actually didn't know hostNetwork was an attribute on pods. I'd be interested in having a chart variable that sets that. Feel like submitting a PR for that?

[LMSSonos]

I had a look into nodePort and that does not work to forward UDP Broadcasts.

About the hostNetwork: true, I would not use that - it is also not recommended by Kubernetes - and that's why I have already spent many hours to investigate this issue and find a workaround ;-)