support Amazon Linux 2 worker nodes

[JacobGabrielson]

Tell us about your request

Presently karpenter supports, for AWS nodes, custom Launch Templates and Bottlerocket. This is a request to also support Amazon Linux 2.

Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?

Some customers may wish to use AL2 because of familiarity or support for specific hardware.

Are you currently working around this issue?

Customers can use custom launch templates, but that does involve extra work and it seems better to just support
it directly as an option.

Additional context

n/a

Attachments

Most likely, the support should turn on the containerd-only flag:

https://github.com/awsdocs/amazon-eks-user-guide/blob/master/doc_source/eks-optimized-ami.md#containerd-bootstrap

Community Note

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[JacobGabrielson]

Useful info:

# Custom Bottlerocket
CLUSTER_NAME=$CLUSTER_NAME
KUBERNETES_VERSION=1.20
ARCHITECTURE=x86_64

USER_DATA=$(cat <<EOF | base64
[settings.kubernetes]
cluster-name = "${CLUSTER_NAME}"
api-server = $(aws eks describe-cluster --name $CLUSTER_NAME --query "cluster.endpoint")
cluster-certificate = $(aws eks describe-cluster --name $CLUSTER_NAME --query "cluster.certificateAuthority.data")
EOF
)

LAUNCH_TEMPLATE="$(cat <<-EOF
    {
      "ImageId": $(aws ssm get-parameter --name /aws/service/bottlerocket/aws-k8s-$KUBERNETES_VERSION/$ARCHITECTURE/latest/image_id --query "Parameter.Value"),
      "SecurityGroupIds": [$(aws eks describe-cluster --name $CLUSTER_NAME --query "cluster.resourcesVpcConfig.clusterSecurityGroupId")],
      "IamInstanceProfile": { "Name": "KarpenterNodeInstanceProfile-${CLUSTER_NAME}" },
      "TagSpecifications": [{"ResourceType": "instance", "Tags": [{ "Key": "kubernetes.io/cluster/$CLUSTER_NAME ", "Value": "owned" }]}],
      "UserData": "${USER_DATA}"
    }
EOF
)"

aws ec2 create-launch-template \
    --launch-template-name KarpenterCustomBottlerocket \
    --launch-template-data "${LAUNCH_TEMPLATE}"


# Custom EKS Optimized AMI
CLUSTER_NAME=$CLUSTER_NAME
B64_CLUSTER_CA=$(aws eks describe-cluster --name $CLUSTER_NAME --query "cluster.certificateAuthority.data")
API_SERVER_URL=$(aws eks describe-cluster --name $CLUSTER_NAME --query "cluster.endpoint")
USER_DATA=$(cat <<EOF | base64
#!/bin/bash
set -ex
/etc/eks/bootstrap.sh $CLUSTER_NAME --b64-cluster-ca $B64_CLUSTER_CA --apiserver-endpoint $API_SERVER_URL --dns-cluster-ip 10.100.0.10
EOF
)

KUBERNETES_VERSION=1.20
ARCHITECTURE=x86_64
LAUNCH_TEMPLATE="$(cat <<-EOF
    {
      "ImageId": $(aws ssm get-parameter --name /aws/service/eks/optimized-ami/${KUBERNETES_VERSION}/amazon-linux-2/recommended/image_id --region us-west-2 --query "Parameter.Value"),
      "SecurityGroupIds": [$(aws eks describe-cluster --name $CLUSTER_NAME --query "cluster.resourcesVpcConfig.clusterSecurityGroupId")],
      "IamInstanceProfile": { "Name": "KarpenterNodeInstanceProfile-${CLUSTER_NAME}" },
      "TagSpecifications": [{"ResourceType": "instance", "Tags": [{ "Key": "kubernetes.io/cluster/$CLUSTER_NAME ", "Value": "owned" }]}],
      "UserData": "${USER_DATA}"
    }
EOF
)"

aws ec2 create-launch-template \
    --launch-template-name KarpenterCustomEKSOptimizedAMI \
    --launch-template-data "${LAUNCH_TEMPLATE}"

[JacobGabrielson]

Fixed by #668