Issue with Agones Game Server Connectivity Using Cilium CNI

[MuhanedYahya]

Issue Summary:
I am experiencing issues connecting to a game server after deploying Agones in a Kubernetes cluster. The connection works correctly with Flannel as the CNI but fails when using Cilium.
Environment Details:

Kubernetes Version: v1.30
Cluster Setup: 3-node cluster using Vagrant on VirtualBox
Network Configuration: Nodes are configured with public_network, making them accessible on my local network.
CNI: Cilium
Load Balancer: MetalLB
Agones Version: 1.41.0

Problem Description:
After deploying Agones and a game server (using the sample game server from the Agones examples), I cannot establish a connection to the game server using the node IP and assigned port. When I switch the CNI from Cilium to Flannel, the connection works as expected. However, with Cilium, the connection fails.
Steps to Reproduce:

1. Set up a 3-node Kubernetes cluster using Vagrant and VirtualBox.
2. Configure the nodes to use public_network.
3. Install Cilium as the CNI.
4. Deploy MetalLB as the load balancer.
5. Deploy Agones (v1.41.0).
6. Deploy a sample game server from the Agones examples.
7. Attempt to connect to the game server using the node IP and assigned port.

Observations:
The connection is successful when using Flannel as the CNI.
The issue arises only when using Cilium as the CNI.

Expected Behavior:
I expect to connect to the game server using the node IP and port when Cilium is configured as the CNI.
Actual Behavior:

The connection fails with Cilium as the CNI.
Additional Information:

No errors were observed in the logs of the game server or Agones components.
Cilium and MetalLB appear to be functioning correctly in other scenarios (e.g., standard Kubernetes service networking).

Request:
Could you please provide guidance on how to resolve this issue or suggest any specific configurations that might be causing this conflict between Agones and Cilium?

[Syntax3rror404]

Looks like you dont use Cilium and still Metallb

[MuhanedYahya]

Looks like you dont use Cilium and still Metallb

MetalLB is a load-balancing solution and not directly related to the CNI. I mentioned MetalLB because I'm using it for load balancing in this setup. I could have configured Cilium IPAM L2 for load balancing as well, but I decided not to pursue that option to keep the setup simpler. If there's any other recommendation for this configuration, I'm open to suggestions.

[Syntax3rror404]

Looks like you dont use Cilium and still Metallb

MetalLB is a load-balancing solution and not directly related to the CNI. I mentioned MetalLB because I'm using it for load balancing in this setup. I could have configured Cilium IPAM L2 for load balancing as well, but I decided not to pursue that option to keep the setup simpler. If there's any other recommendation for this configuration, I'm open to suggestions.

I also had many problems with Metallb. Try it with Cilium as L2 LB like Metallb or with BGP if you have BGP.
https://docs.cilium.io/en/stable/network/lb-ipam/

[MuhanedYahya]

Looks like you dont use Cilium and still Metallb

MetalLB is a load-balancing solution and not directly related to the CNI. I mentioned MetalLB because I'm using it for load balancing in this setup. I could have configured Cilium IPAM L2 for load balancing as well, but I decided not to pursue that option to keep the setup simpler. If there's any other recommendation for this configuration, I'm open to suggestions.

I also had many problems with Metallb. Try it with Cilium as L2 LB like Metallb or with BGP if you have BGP. https://docs.cilium.io/en/stable/network/lb-ipam/

I am sure that this is not a load balancing problem. agones assigns externalP to game servers, so loadbalancing is not used in this case.

[Syntax3rror404]

Looks like you dont use Cilium and still Metallb

MetalLB is a load-balancing solution and not directly related to the CNI. I mentioned MetalLB because I'm using it for load balancing in this setup. I could have configured Cilium IPAM L2 for load balancing as well, but I decided not to pursue that option to keep the setup simpler. If there's any other recommendation for this configuration, I'm open to suggestions.

I also had many problems with Metallb. Try it with Cilium as L2 LB like Metallb or with BGP if you have BGP. https://docs.cilium.io/en/stable/network/lb-ipam/

I am sure that this is not a load balancing problem. agones assigns externalP to game servers, so loadbalancing is not used in this case.

Are you sure, because you also gets a kuberentes service with the kind loadbalancer with a external IP which a loadbalancer like metallb or cilium needs to announce

[MuhanedYahya]

Looks like you dont use Cilium and still Metallb

MetalLB is a load-balancing solution and not directly related to the CNI. I mentioned MetalLB because I'm using it for load balancing in this setup. I could have configured Cilium IPAM L2 for load balancing as well, but I decided not to pursue that option to keep the setup simpler. If there's any other recommendation for this configuration, I'm open to suggestions.

I also had many problems with Metallb. Try it with Cilium as L2 LB like Metallb or with BGP if you have BGP. https://docs.cilium.io/en/stable/network/lb-ipam/

I am sure that this is not a load balancing problem. agones assigns externalP to game servers, so loadbalancing is not used in this case.

Are you sure, because you also gets a kuberentes service with the kind loadbalancer with a external IP which a loadbalancer like metallb or cilium needs to announce
agones allocates the IP of one of the nodes as externalIP to the game servers. Where exactly is the loadbalancer here?

[Syntax3rror404]

Its in you're description that you using metallb as loadbalancer so I think you're using metallb as loadbalancer?!

Kubernetes Version: v1.30
Cluster Setup: 3-node cluster using Vagrant on VirtualBox
Network Configuration: Nodes are configured with public_network, making them accessible on my local network.
CNI: Cilium
Load Balancer: MetalLB
Agones Version: 1.41.0

[MuhanedYahya]

Yes, I was explaining my setup, but this is not important for agones because the game servers do not use load balancers.