Daemonset Antiaffinity for Fargate Nodes

[ghost]

Is this a bug fix or adding new feature?

Bug fix. Relating to Issue 328

What is this PR about? / Why do we need it?

By default when following the docs at [1] with a mixed ec2/fargate EKS cluster the efs-csi-node DaemonSet will try to schedule to fargate nodes which results in pods becoming stuck in the "Pending" status.

This is easily resolvable with a node anti affinity rule.

[1] https://docs.aws.amazon.com/eks/latest/userguide/efs-csi.html

What testing is done?

I have tested the changes on my branch within a test cluster using the command below which is the exact command from the documentation but with a modified endpoint pointing to my test branch.

kubectl apply -k https://github.com/benmccown-amz/aws-efs-csi-driver/deploy/kubernetes/overlays/stable/ecr?ref=daemonset-antiaffinity-fargate

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[ghost]

Just got CLA sorted.

[wongma7]

/approve

thank you, could you squash the commits into 1. e.g. git rebase -i upstream/master ``

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: benmccown-amz, wongma7

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[wongma7]

/ok-to-test

[ghost]

@wongma7 commits have been squashed.

[wongma7]

/lgtm

thanks again

[wongma7]

/test pull-aws-efs-csi-driver-e2e

[wongma7]

/test pull-aws-efs-csi-driver-e2e

[nicogl]

@wongma7 @ben-mccown
The DaemonSet antiaffinity for Fargate nodes introduced here doesn't solve the issue. I tested it and still get PodNotSupported errors. I think the problem is that the way the "matchExpressions" element is defined doesn't have an infuence on the NodeGroup nodes:

    - matchExpressions:
        - key: eks.amazonaws.com/compute-type
          operator: NotIn
          values:
          - fargate

As per my understanding, above condition requires that the label "eks.amazonaws.com/compute-type" exists on the node for it to be evaluated. Now note that this label is only present on Fargate nodes, not on EC2 nodes beloging to a node group. This can be checked by running this command: kubectl get nodes --show-labels

The way I fixed it was changing the affinity to:

      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: eks.amazonaws.com/nodegroup
                operator: Exists
                values: []

This way I ensure that the related pods are run on a node group and not Fargate.

Last but not least, this affinity also has to be added to the "efs-csi-controller" Deployment element. Otherwise, the controller pods also throw errors.

Hope this makes sense, kind regards.