Karpenter EC2NodeClass aws mount nvme /var/lib/containerd

gistfile1.txt

apiVersion: karpenter.k8s.aws/v1beta1
kind: EC2NodeClass
metadata:
  name: gitlab-runner
spec:
  amiFamily: AL2023
  blockDeviceMappings: []
  userData: |
    MIME-Version: 1.0
    Content-Type: multipart/mixed; boundary="BOUNDARY"

    --BOUNDARY
    Content-Type: text/x-shellscript; charset="us-ascii"

    #!/bin/bash
    echo "Running a custom user data script"
    set -ex

    yum install -y mdadm nvme-cli rsync
    systemctl stop containerd
    nvme_disks=($(nvme list | grep "Amazon EC2 NVMe Instance Storage" | awk -F'[[:space:]][[:space:]]+' '{print $1}'))
    if [[ ${#nvme_disks[@]} -ge 2 ]]; then
      mdadm --create --verbose /dev/md0 --level=0 --raid-devices=${#nvme_disks[@]} ${nvme_disks[*]} &&
      mkfs.ext4 -F /dev/md0 &&
      mv /var/lib/containerd/ /var/lib/containerd-original &&
      mkdir /var/lib/containerd &&
      mount /dev/md0 /var/lib/containerd &&
      rsync -a /var/lib/containerd-original/ /var/lib/containerd/ &&
      rm -rf /var/lib/containerd-original &&
      chmod 750 /var/lib/containerd &&
      systemctl start containerd
    else
      echo "Not enough NVMe disks available for RAID 0 configuration."
    fi
    --BOUNDARY--

FYI, with the approach above ^ karpenter will not be able to schedule nodes if pods are requesting ephemeral storage
The correct way to use NVME is to set

instanceStorePolicy: "RAID0"

https://karpenter.sh/v1.7/concepts/nodeclasses/#specinstancestorepolicy