[EKS] Use Multus with existing cluster created by eksctl

Question

we created and manage our EKS cluster with eksctl for quite a while. Now we are faced with a use-case where we need multiple interfaces in a pod. EKS supports multus to do exactly this. All documentations I'm able to find start with a cloudformation script to setup new nodegroups.

Im not exactly sure how to integrate this into our existsing workflow with eksctl. We already have running nodes. So I just skipped that step and installed the multus daemonset with the existing nodes and tried to assign a second interface to a container which didnt work. I checked the cloudformation script and it does multus spefic stuff (Im not familiar with cloudformation scripts) .

Q: Can I somehow patch existing nodes in order to support Multus?

Answer

You can follow this quickstart guide to setup Multus CNI for your EKS cluster - https://github.com/k8snetworkplumbingwg/multus-cni/blob/master/docs/quickstart.md

In this setup, you will need to clone this github [repo](https://github.com/k8snetworkplumbingwg/multus-cni) and install a daemonset (multus-daemonset-thick-plugin.yml) which creates pods that are responsible for patching your existing nodes with Multus CNI configuration.

After the nodes are patched, you can create the `NetworkAttachmentDefinition` CRD to define your network configuration as specified [here](https://github.com/k8snetworkplumbingwg/multus-cni/blob/master/docs/quickstart.md#storing-a-configuration-as-a-custom-resource).

After creating the above CRD, you'll need to add the annotation `k8s.v1.cni.cncf.io/networks` to your pod/deployment manifest to assign additional ENIs to your new pods.

I hope this helps!

[EKS] Use Multus with existing cluster created by eksctl

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