Customize Amazon EKS launch templates - AWS Batch
Add kubelet extra argumentsConfigure the container runtimeMount an Amazon EFS volumeIPv6 support

Customize Amazon EKS launch templates

AWS Batch on Amazon EKS supports launch templates. There are constraints on what your launch template can do.

Important

  • For EKS AL2 AMIs, AWS Batch runs /etc/eks/bootstrap.sh. Don't run /etc/eks/bootstrap.sh in your launch template or cloud-init user-data scripts. You can add additional parameters besides the --kubelet-extra-args parameter to bootstrap.sh. To do this, set the AWS_BATCH_KUBELET_EXTRA_ARGS variable in the /etc/aws-batch/batch.config file. See the following example for details.

  • For EKS AL2023, AWS Batch utilizes the NodeConfigSpec from EKS to make instances join the EKS cluster. AWS Batch populates ClusterDetails in NodeConfigSpec for the EKS cluster and you don't need to specify them.

Note

We recommend that you do not set any of the follow NodeConfigSpec settings in the launch template as AWS Batch will override your values. For more information, see Shared responsibility of the Kubernetes nodes.

  • Taints

  • Cluster Name

  • apiServerEndpoint

  • certificatAuthority

  • CIDR

  • Do not create a labels with the prefix batch.amazonaws.com/

Note

If the launch template is changed after CreateComputeEnvironment is called, UpdateComputeEnvironment must be called to evaluate the version of the launch template for replacement.

Add kubelet extra arguments

AWS Batch supports adding extra arguments to the kubelet command. For the list of supported parameters, see kubelet in the Kubernetes documentation. In the following example for EKS AL2 AMIs, --node-labels mylabel=helloworld is added to the kubelet command line.

MIME-Version: 1.0
      Content-Type: multipart/mixed; boundary="==MYBOUNDARY=="

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

      #!/bin/bash
      mkdir -p /etc/aws-batch

      echo AWS_BATCH_KUBELET_EXTRA_ARGS=\"--node-labels mylabel=helloworld\" >> /etc/aws-batch/batch.config

      --==MYBOUNDARY==--

For EKS AL2023 AMIs the file format is YAML. For the list of supported parameters, see NodeConfigSpec in the Kubernetes documentation. In the following example for EKS AL2023 AMIs, --node-labels mylabel=helloworld is added to the kubelet command line.

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="==MYBOUNDARY=="

--==MYBOUNDARY==
Content-Type: application/node.eks.aws

apiVersion: node.eks.aws/v1alpha1
kind: NodeConfig
spec:
  kubelet:
    flags:
    - --node-labels=mylabel=helloworld

--==MYBOUNDARY==--

Configure the container runtime

You can use the AWS Batch CONTAINER_RUNTIME environment variable to configure the container runtime on a managed node. The following example sets the container runtime to containerd when bootstrap.sh runs. For more information, see containerd in the Kubernetes documentation.

If you are using an optimized EKS_AL2023 or EKS_AL2023_NVIDIA AMI you do not need to specify the container runtime as only containerd is supported.

Note

The CONTAINER_RUNTIME environment variable is equivalent to the --container-runtime option of bootstrap.sh. For more information, see Options in the Kubernetes documentation.

MIME-Version: 1.0
      Content-Type: multipart/mixed; boundary="==MYBOUNDARY=="

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

      #!/bin/bash
      mkdir -p /etc/aws-batch

      echo CONTAINER_RUNTIME=containerd >> /etc/aws-batch/batch.config

      --==MYBOUNDARY==--

Mount an Amazon EFS volume

You can use launch templates to mount volumes to the node. In the following example, the cloud-config packages and runcmd settings are used. For more information, see Cloud config examples in the cloud-init documentation.

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="==MYBOUNDARY=="

--==MYBOUNDARY==
Content-Type: text/cloud-config; charset="us-ascii"

packages:
- amazon-efs-utils

runcmd:
- file_system_id_01=fs-abcdef123
- efs_directory=/mnt/efs

- mkdir -p ${efs_directory}
- echo "${file_system_id_01}:/ ${efs_directory} efs _netdev,noresvport,tls,iam 0 0" >> /etc/fstab
- mount -t efs -o tls ${file_system_id_01}:/ ${efs_directory}

--==MYBOUNDARY==--

To use this volume in the job, it must be added in the eksProperties parameter to RegisterJobDefinition. The following example is a large portion of the job definition.

{
    "jobDefinitionName": "MyJobOnEks_EFS",
    "type": "container",
    "eksProperties": {
        "podProperties": {
            "containers": [
                {
                    "image": "public.ecr.aws/amazonlinux/amazonlinux:2",
                    "command": ["ls", "-la", "/efs"],
                    "resources": {
                        "limits": {
                            "cpu": "1",
                            "memory": "1024Mi"
                        }
                    },
                    "volumeMounts": [
                        {
                            "name": "efs-volume",
                            "mountPath": "/efs"
                        }
                    ]
                }
            ],
            "volumes": [
                {
                    "name": "efs-volume",
                    "hostPath": {
                        "path": "/mnt/efs"
                    }
                }
            ]
        }
    }
}

In the node, the Amazon EFS volume is mounted in the /mnt/efs directory. In the container for the Amazon EKS job, the volume is mounted in the /efs directory.

IPv6 support

AWS Batch supports Amazon EKS clusters that have IPv6 addresses. No customizations are required for AWS Batch support. However, before you begin, we recommend that you review the considerations and conditions that are outlined in Assigning IPv6 addresses to pods and services in the Amazon EKS User Guide.