What does configuring EKS node groups look like with Gruntwork?

[zackproser]

A customer asked:

Can you modify the EKS node groups following a Reference Architecture deployment? Can you provide me some examples of what it looks like to configure node groups using Gruntwork's modules?

[zackproser]

Firstly, you can definitely modify the EKS cluster node groups following a Reference Architecture deployment. One of the benefits of having a Reference Architecture deployed is that you receive 100% of the code, so you can modify it however you wish.

Secondly, here's some examples of what it looks like to configure Node groups in terragrunt:

managed_node_group_configurations = {
    group = {
      min_size       = 2
      max_size       = 4
      desired_size   = 2
      instance_types = ["t3.micro"]
      subnet_ids     = dependency.vpc.outputs.private_app_subnet_ids
    }
  }
  cluster_instance_ami_filters = {
    owners = [local.common_vars.locals.account_ids.shared]
    filters = [
      {
        name   = "name"
        values = ["eks-workers-v0.70.0-*"]
      },
    ]
  }

Here's the configuration format for Node groups in our eks-cluster module:

variable "managed_node_group_configurations" {
  description = "Configure one or more Node Groups to manage the EC2 instances in this cluster. Set to empty object ({}) if you do not wish to configure managed node groups."
  # Ideally, this would be a map of (string, object), with all the supported properties, but object does not support
  # optional properties. We can't use a map(any) either as that would require the values to all have the same type.
  type = any

  # Each configuration must be keyed by a unique string that will be used as a suffix for the node group name. The
  # values support the following attributes:
  #
  #
  # OPTIONAL (defaults to value of corresponding module input):
  # - subnet_ids          list(string)       : (Defaults to value from var.node_group_default_subnet_ids) A list of the
  #                                            subnets into which the EKS Cluster's managed nodes will be launched.
  #                                            These should usually be all private subnets and include one in each AWS
  #                                            Availability Zone. NOTE: If using a cluster autoscaler with EBS volumes,
  #                                            each ASG may only belong to a single availability zone.
  # - min_size            number             : (Defaults to value from var.node_group_default_min_size) The minimum
  #                                            number of EC2 Instances representing workers launchable for this EKS
  #                                            Cluster. Useful for auto-scaling limits.
  # - max_size            number             : (Defaults to value from var.node_group_default_max_size) The maximum
  #                                            number of EC2 Instances representing workers that must be running for
  #                                            this EKS Cluster. We recommend making this at least twice the min_size,
  #                                            even if you don't plan on scaling the cluster up and down, as the extra
  #                                            capacity will be used to deploy updates to the cluster.
  # - desired_size        number             : (Defaults to value from var.node_group_default_desired_size) The current
  #                                            desired number of EC2 Instances representing workers that must be running
  #                                            for this EKS Cluster.
  # - instance_types      list(string)       : (Defaults to value from var.node_group_default_instance_types) A list of
  #                                            instance types (e.g., t2.medium) to use for the EKS Cluster's worker
  #                                            nodes. EKS will choose from this list of instance types when launching
  #                                            new instances. When using launch templates, this setting will override
  #                                            the configured instance type of the launch template.
  # - capacity_type       string             : (Defaults to value from var.node_group_default_capacity_type) Type of capacity
  #                                            associated with the EKS Node Group. Valid values: ON_DEMAND, SPOT.
  # - launch_template     LaunchTemplate     : (Defaults to value from var.node_group_default_launch_template)
  #                                            Launch template to use for the node. Specify either Name or ID of launch
  #                                            template. Must include version. Although the API supports using the
  #                                            values "$Latest" and "$Default" to configure the version, this can lead
  #                                            to a perpetual diff. Use the `latest_version` or `default_version` output
  #                                            of the aws_launch_template data source or resource instead. See
  #                                            https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/eks_node_group#launch_template-configuration-block
  #                                            for more information.
  # - instance_root_volume_size   number     : (Defaults to value from var.node_group_default_instance_root_volume_size)
  #                                            The root volume size of instances to use for the ASG in GB (e.g., 40).
  # - instance_root_volume_type   string     : (Defaults to value from var.node_group_default_instance_root_volume_type)
  #                                            The root volume type of instances to use for the ASG (e.g., "standard").
  # - instance_root_volume_encryption  bool  : (Defaults to value from var.node_group_default_instance_root_volume_encryption)
  #                                             Whether or not to enable root volume encryption for instances of the ASG.
  # - tags                map(string)        : (Defaults to value from var.node_group_default_tags) Custom tags to apply
  #                                            to the EC2 Instances in this node group. This should be a key value pair,
  #                                            where the keys are tag keys and values are the tag values. Merged with
  #                                            var.common_tags.
  # - labels              map(string)        : (Defaults to value from var.node_group_default_labels) Custom Kubernetes
  #                                            Labels to apply to the EC2 Instances in this node group. This should be a
  #                                            key value pair, where the keys are label keys and values are the label
  #                                            values. Merged with var.common_labels.
  # - eks_kubelet_extra_args        string   : Extra args to pass to the kubelet process on node boot.
  # - eks_bootstrap_script_options  string   : Extra option args to pass to the bootstrap.sh script. This will be
  #                                            passed through directly to the bootstrap script.
  # - cloud_init_parts    map(string)        : (Defaults to value from var.cloud_init_parts)
  #                                            Per-ASG cloud init scripts to run at boot time on the node.  See var.cloud_init_parts for accepted keys.
  #
  # Structure of LaunchTemplate object:
  # - name     string  : The Name of the Launch Template to use. One of ID or Name should be provided.
  # - id       string  : The ID of the Launch Template to use. One of ID or Name should be provided.
  # - version  string  : The version of the Launch Template to use.
  #
  # Example:
  # managed_node_group_configurations = {
  #   ngroup1 = {
  #     desired_size = 1
  #     min_size     = 1
  #     max_size     = 3
  #     subnet_ids  = [data.terraform_remote_state.vpc.outputs.private_app_subnet_ids[0]]
  #   }
  #   asg2 = {
  #     desired_size   = 1
  #     min_size       = 1
  #     max_size       = 3
  #     subnet_ids     = [data.terraform_remote_state.vpc.outputs.private_app_subnet_ids[0]]
  #     disk_size      = 50
  #   }
  #   ngroup2 = {}  # Only defaults
  # }
  default = {}
}