karpenter-controller

This component provisions Karpenter on an EKS cluster. It requires at least version 0.32.0 of Karpenter, though you are encouraged to use the latest version.

Usage

Stack Level: Regional

These instructions assume you are provisioning 2 EKS clusters in the same account and region, named "blue" and "green", and alternating between them. If you are only using a single cluster, you can ignore the "blue" and "green" references and remove the metadata block from the karpenter module.

components:
  terraform:
    # Base component of all `karpenter` components
    eks/karpenter:
      metadata:
        type: abstract
      vars:
        enabled: true
        eks_component_name: "eks/cluster"
        name: "karpenter"
        # https://github.com/aws/karpenter/tree/main/charts/karpenter
        chart_repository: "oci://public.ecr.aws/karpenter"
        chart: "karpenter"
        chart_version: "v0.36.0"
        # Enable Karpenter to get advance notice of spot instances being terminated
        # See https://karpenter.sh/docs/concepts/#interruption
        interruption_handler_enabled: true
        resources:
          limits:
            cpu: "300m"
            memory: "1Gi"
          requests:
            cpu: "100m"
            memory: "512Mi"
        cleanup_on_fail: true
        atomic: true
        wait: true
        rbac_enabled: true
        # "karpenter-crd" can be installed as an independent helm chart to manage the lifecycle of Karpenter CRDs
        crd_chart_enabled: true
        crd_chart: "karpenter-crd"
        # replicas set the number of Karpenter controller replicas to run
        replicas: 2
        # "settings" controls a subset of the settings for the Karpenter controller regarding batch idle and max duration.
        # you can read more about these settings here: https://karpenter.sh/docs/reference/settings/
        settings:
          batch_idle_duration: "1s"
          batch_max_duration: "10s"
        # The logging settings for the Karpenter controller
        logging:
          enabled: true
          level:
            controller: "info"
            global: "info"
            webhook: "error"

Provision Karpenter on EKS cluster

Here we describe how to provision Karpenter on an EKS cluster. We will be using the plat-ue2-dev stack as an example.

Provision Service-Linked Roles for EC2 Spot and EC2 Spot Fleet

Note: If you want to use EC2 Spot for the instances launched by Karpenter, you may need to provision the following Service-Linked Role for EC2 Spot:

Service-Linked Role for EC2 Spot

This is only necessary if this is the first time you're using EC2 Spot in the account. Since this is a one-time operation, we recommend you do this manually via the AWS CLI:

aws --profile <namespace>-<tenamt>-gbl-<stage>-admin iam create-service-linked-role --aws-service-name spot.amazonaws.com

Note that if the Service-Linked Roles already exist in the AWS account (if you used EC2 Spot or Spot Fleet before), and you try to provision them again, you will see the following errors:

An error occurred (InvalidInput) when calling the CreateServiceLinkedRole operation:
Service role name AWSServiceRoleForEC2Spot has been taken in this account, please try a different suffix

For more details, see:

The process of provisioning Karpenter on an EKS cluster consists of 3 steps.

1. Provision EKS IAM Role for Nodes Launched by Karpenter

note

VPC assumptions being made

We assume you've already created a VPC using our VPC component and have private subnets already set up. The Karpenter node pools will be launched in the private subnets.

EKS IAM Role for Nodes launched by Karpenter are provisioned by the eks/cluster component. (EKS can also provision a Fargate Profile for Karpenter, but deploying Karpenter to Fargate is not recommended.):

components:
  terraform:
    eks/cluster-blue:
      metadata:
        component: eks/cluster
        inherits:
          - eks/cluster
      vars:
        karpenter_iam_role_enabled: true

note

The AWS Auth API for EKS is used to authorize the Karpenter controller to interact with the EKS cluster.

Karpenter is installed using a Helm chart. The Helm chart installs the Karpenter controller and a webhook pod as a Deployment that needs to run before the controller can be used for scaling your cluster. We recommend a minimum of one small node group with at least one worker node.

As an alternative, you can run these pods on EKS Fargate by creating a Fargate profile for the karpenter namespace. Doing so will cause all pods deployed into this namespace to run on EKS Fargate. Do not run Karpenter on a node that is managed by Karpenter.

See Run Karpenter Controller... for more details.

We provision IAM Role for Nodes launched by Karpenter because they must run with an Instance Profile that grants permissions necessary to run containers and configure networking.

We define the IAM role for the Instance Profile in components/terraform/eks/cluster/controller-policy.tf.

Note that we provision the EC2 Instance Profile for the Karpenter IAM role in the components/terraform/eks/karpenter component (see the next step).

Run the following commands to provision the EKS Instance Profile for Karpenter and the IAM role for instances launched by Karpenter on the blue EKS cluster and add the role ARNs to the EKS Auth API:

atmos terraform plan eks/cluster-blue -s plat-ue2-dev
atmos terraform apply eks/cluster-blue -s plat-ue2-dev

For more details, refer to:

2. Provision `karpenter` component

In this step, we provision the components/terraform/eks/karpenter component, which deploys the following resources:

Karpenter CustomerResourceDefinitions (CRDs) using the Karpenter CRD Chart and the helm_release Terraform resource
Karpenter Kubernetes controller using the Karpenter Helm Chart and the helm_release Terraform resource
EKS IAM role for Kubernetes Service Account for the Karpenter controller (with all the required permissions)
An SQS Queue and Event Bridge rules for handling Node Interruption events (i.e. Spot)

Create a stack config for the blue Karpenter component in stacks/catalog/eks/clusters/blue.yaml:

eks/karpenter-blue:
  metadata:
    component: eks/karpenter
    inherits:
      - eks/karpenter
  vars:
    eks_component_name: eks/cluster-blue

Run the following commands to provision the Karpenter component on the blue EKS cluster:

atmos terraform plan eks/karpenter-blue -s plat-ue2-dev
atmos terraform apply eks/karpenter-blue -s plat-ue2-dev

3. Provision `karpenter-node-pool` component

In this step, we provision the components/terraform/eks/karpenter-node-pool component, which deploys Karpenter NodePools using the kubernetes_manifest resource.

tip

Why use a separate component for NodePools?

We create the NodePools as a separate component since the CRDs for the NodePools are created by the Karpenter component. This helps manage dependencies.

First, create an abstract component for the eks/karpenter-node-pool component:

components:
  terraform:
    eks/karpenter-node-pool:
      metadata:
        type: abstract
      vars:
        enabled: true
        # Disabling Manifest Experiment disables stored metadata with Terraform state
        # Otherwise, the state will show changes on all plans
        helm_manifest_experiment_enabled: false
        node_pools:
          default:
            # Whether to place EC2 instances launched by Karpenter into VPC private subnets. Set it to `false` to use public subnets
            private_subnets_enabled: true
            # You can use disruption to set the maximum instance lifetime for the EC2 instances launched by Karpenter.
            # You can also configure how fast or slow Karpenter should add/remove nodes.
            # See more: https://karpenter.sh/v0.36/concepts/disruption/
            disruption:
              max_instance_lifetime: "336h" # 14 days
            # Taints can be used to prevent pods without the right tolerations from running on this node pool.
            # See more: https://karpenter.sh/v0.36/concepts/nodepools/#taints
            taints: []
            total_cpu_limit: "1k"
            # Karpenter node pool total memory limit for all pods running on the EC2 instances launched by Karpenter
            total_memory_limit: "1200Gi"
            # Set acceptable (In) and unacceptable (Out) Kubernetes and Karpenter values for node provisioning based on
            # Well-Known Labels and cloud-specific settings. These can include instance types, zones, computer architecture,
            # and capacity type (such as AWS spot or on-demand).
            # See https://karpenter.sh/v0.36/concepts/nodepools/#spectemplatespecrequirements for more details
            requirements:
              - key: "karpenter.sh/capacity-type"
                operator: "In"
                # See https://karpenter.sh/docs/concepts/nodepools/#capacity-type
                # Allow fallback to on-demand instances when spot instances are unavailable
                # By default, Karpenter uses the "price-capacity-optimized" allocation strategy
                # https://aws.amazon.com/blogs/compute/introducing-price-capacity-optimized-allocation-strategy-for-ec2-spot-instances/
                # It is currently not configurable, but that may change in the future.
                # See https://github.com/aws/karpenter-provider-aws/issues/1240
                values:
                  - "on-demand"
                  - "spot"
              - key: "kubernetes.io/os"
                operator: "In"
                values:
                  - "linux"
              - key: "kubernetes.io/arch"
                operator: "In"
                values:
                  - "amd64"
              # The following two requirements pick instances such as c3 or m5
              - key: karpenter.k8s.aws/instance-category
                operator: In
                values: ["c", "m", "r"]
              - key: karpenter.k8s.aws/instance-generation
                operator: Gt
                values: ["2"]

Now, create the stack config for the blue Karpenter NodePool component in stacks/catalog/eks/clusters/blue.yaml:

eks/karpenter-node-pool/blue:
  metadata:
    component: eks/karpenter-node-pool
    inherits:
      - eks/karpenter-node-pool
  vars:
    eks_component_name: eks/cluster-blue

Finally, run the following commands to deploy the Karpenter NodePools on the blue EKS cluster:

atmos terraform plan eks/karpenter-node-pool/blue -s plat-ue2-dev
atmos terraform apply eks/karpenter-node-pool/blue -s plat-ue2-dev

Node Interruption

Karpenter also supports listening for and responding to Node Interruption events. If interruption handling is enabled, Karpenter will watch for upcoming involuntary interruption events that would cause disruption to your workloads. These interruption events include:

Spot Interruption Warnings
Scheduled Change Health Events (Maintenance Events)
Instance Terminating Events
Instance Stopping Events

tip

Interruption Handler vs. Termination Handler

The Node Interruption Handler is not the same as the Node Termination Handler. The latter is always enabled and cleanly shuts down the node in 2 minutes in response to a Node Termination event. The former gets advance notice that a node will soon be terminated, so it can have 5-10 minutes to shut down a node.

For more details, see refer to the Karpenter docs and FAQ

To enable Node Interruption handling, set var.interruption_handler_enabled to true. This will create an SQS queue and a set of Event Bridge rules to deliver interruption events to Karpenter.

Custom Resource Definition (CRD) Management

Karpenter ships with a few Custom Resource Definitions (CRDs). In earlier versions of this component, when installing a new version of the karpenter helm chart, CRDs were not be upgraded at the same time, requiring manual steps to upgrade CRDs after deploying the latest chart. However Karpenter now supports an additional, independent helm chart for CRD management. This helm chart, karpenter-crd, can be installed alongside the karpenter helm chart to automatically manage the lifecycle of these CRDs.

To deploy the karpenter-crd helm chart, set var.crd_chart_enabled to true. (Installing the karpenter-crd chart is recommended. var.crd_chart_enabled defaults to false to preserve backward compatibility with older versions of this component.)

Troubleshooting

For Karpenter issues, checkout the Karpenter Troubleshooting Guide

References

For more details on the CRDs, see:

Variables

Required Variables

chart (string) required

Chart name to be installed. The chart name can be local path, a URL to a chart, or the name of the chart if repository is specified. It is also possible to use the <repository>/<chart> format here if you are running Terraform on a system that the repository has been added to with helm repo add but this is not recommended

chart_repository (string) required

Repository URL where to locate the requested chart

region (string) required

AWS Region

resources required

The CPU and memory of the deployment's limits and requests

Type:

object({
limits = object({
  cpu    = string
  memory = string
})
requests = object({
  cpu    = string
  memory = string
})
})

Optional Variables

atomic (bool) optional

If set, installation process purges chart on fail. The wait flag will be set automatically if atomic is used

Default value: true

chart_description (string) optional

Set release description attribute (visible in the history)

Default value: null

chart_values (any) optional

Additional values to yamlencode as helm_release values

Default value: { }

chart_version (string) optional

Specify the exact chart version to install. If this is not specified, the latest version is installed

Default value: null

cleanup_on_fail (bool) optional

Allow deletion of new resources created in this upgrade when upgrade fails

Default value: true

crd_chart (string) optional

The name of the Karpenter CRD chart to be installed, if var.crd_chart_enabled is set to true.

Default value: "karpenter-crd"

crd_chart_enabled (bool) optional

karpenter-crd can be installed as an independent helm chart to manage the lifecycle of Karpenter CRDs. Set to true to install this CRD helm chart before the primary karpenter chart.

Default value: false

eks_component_name (string) optional

The name of the eks component

Default value: "eks/cluster"

helm_manifest_experiment_enabled (bool) optional

Enable storing of the rendered manifest for helm_release so the full diff of what is changing can been seen in the plan

Default value: false

interruption_handler_enabled (bool) optional

If true, deploy a SQS queue and Event Bridge rules to enable interruption handling by Karpenter.
https://karpenter.sh/docs/concepts/disruption/#interruption

Default value: true

interruption_queue_message_retention (number) optional

The message retention in seconds for the interruption handler SQS queue.

Default value: 300

kube_data_auth_enabled (bool) optional

If true, use an aws_eks_cluster_auth data source to authenticate to the EKS cluster.
Disabled by kubeconfig_file_enabled or kube_exec_auth_enabled.

Default value: false

kube_exec_auth_aws_profile (string) optional

The AWS config profile for aws eks get-token to use

Default value: ""

kube_exec_auth_aws_profile_enabled (bool) optional

If true, pass kube_exec_auth_aws_profile as the profile to aws eks get-token

Default value: false

kube_exec_auth_enabled (bool) optional

If true, use the Kubernetes provider exec feature to execute aws eks get-token to authenticate to the EKS cluster.
Disabled by kubeconfig_file_enabled, overrides kube_data_auth_enabled.

Default value: true

kube_exec_auth_role_arn (string) optional

The role ARN for aws eks get-token to use

Default value: ""

kube_exec_auth_role_arn_enabled (bool) optional

If true, pass kube_exec_auth_role_arn as the role ARN to aws eks get-token

Default value: true

kubeconfig_context (string) optional

Context to choose from the Kubernetes config file.
If supplied, kubeconfig_context_format will be ignored.

Default value: ""

kubeconfig_context_format (string) optional

A format string to use for creating the kubectl context name when
kubeconfig_file_enabled is true and kubeconfig_context is not supplied.
Must include a single %s which will be replaced with the cluster name.

Default value: ""

kubeconfig_exec_auth_api_version (string) optional

The Kubernetes API version of the credentials returned by the exec auth plugin

Default value: "client.authentication.k8s.io/v1beta1"

kubeconfig_file (string) optional

The Kubernetes provider config_path setting to use when kubeconfig_file_enabled is true

Default value: ""

kubeconfig_file_enabled (bool) optional

If true, configure the Kubernetes provider with kubeconfig_file and use that kubeconfig file for authenticating to the EKS cluster

Default value: false

logging optional

A subset of the logging settings for the Karpenter controller

Type:

object({
enabled = optional(bool, true)
level = optional(object({
  controller = optional(string, "info")
  global     = optional(string, "info")
  webhook    = optional(string, "error")
}), {})
})

Default value: { }

rbac_enabled (bool) optional

Enable/disable RBAC

Default value: true

replicas (number) optional

The number of Karpenter controller replicas to run

Default value: 2

settings optional

A subset of the settings for the Karpenter controller.
Some settings are implicitly set by this component, such as clusterName and
interruptionQueue. All settings can be overridden by providing a settings
section in the chart_values variable. The settings provided here are the ones
mostly likely to be set to other than default values, and are provided here for convenience.

Type:

object({
batch_idle_duration = optional(string, "1s")
batch_max_duration  = optional(string, "10s")
})

Default value: { }

timeout (number) optional

Time in seconds to wait for any individual kubernetes operation (like Jobs for hooks). Defaults to 300 seconds

Default value: null

wait (bool) optional

Will wait until all resources are in a ready state before marking the release as successful. It will wait for as long as timeout. Defaults to true

Default value: null

Context Variables

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

Additional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id.
This is for some rare cases where resources want additional configuration of tags
and therefore take a list of maps with tag key, value, and additional configuration.

Required: No

Default value: { }

attributes (list(string)) optional

ID element. Additional attributes (e.g. workers or cluster) to add to id,
in the order they appear in the list. New attributes are appended to the
end of the list. The elements of the list are joined by the delimiter
and treated as a single ID element.

Required: No

Default value: [ ]

context (any) optional

Single object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as null to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.

Required: No

Default value:

{
  "additional_tag_map": {},
  "attributes": [],
  "delimiter": null,
  "descriptor_formats": {},
  "enabled": true,
  "environment": null,
  "id_length_limit": null,
  "label_key_case": null,
  "label_order": [],
  "label_value_case": null,
  "labels_as_tags": [
    "unset"
  ],
  "name": null,
  "namespace": null,
  "regex_replace_chars": null,
  "stage": null,
  "tags": {},
  "tenant": null
}

delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.

Required: No

Default value: null

descriptor_formats (any) optional

Describe additional descriptors to be output in the descriptors output map.
Map of maps. Keys are names of descriptors. Values are maps of the form
\{<br/> format = string<br/> labels = list(string)<br/> \}
(Type is any so the map values can later be enhanced to provide additional options.)
format is a Terraform format string to be passed to the format() function.
labels is a list of labels, in order, to pass to format() function.
Label values will be normalized before being passed to format() so they will be
identical to how they appear in id.
Default is {} (descriptors output will be empty).

Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

Limit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for keep the existing setting, which defaults to 0.
Does not affect id_full.

Required: No

Default value: null

label_key_case (string) optional

Controls the letter case of the tags keys (label names) for tags generated by this module.
Does not affect keys of tags passed in via the tags input.
Possible values: lower, title, upper.
Default value: title.

Required: No

Default value: null

label_order (list(string)) optional

The order in which the labels (ID elements) appear in the id.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.

Required: No

Default value: null

label_value_case (string) optional

Controls the letter case of ID elements (labels) as included in id,
set as tag values, and output by this module individually.
Does not affect values of tags passed in via the tags input.
Possible values: lower, title, upper and none (no transformation).
Set this to title and set delimiter to "" to yield Pascal Case IDs.
Default value: lower.

Required: No

Default value: null

labels_as_tags (set(string)) optional

Set of labels (ID elements) to include as tags in the tags output.
Default is to include all labels.
Tags with empty values will not be included in the tags output.
Set to [] to suppress all generated tags.
Notes:
The value of the name tag, if included, will be the id, not the name.
Unlike other null-label inputs, the initial setting of labels_as_tags cannot be
changed in later chained modules. Attempts to change it will be silently ignored.

Required: No

Default value:

[
  "default"
]

name (string) optional

ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'.
This is the only ID element not also included as a tag.
The "name" tag is set to the full id string. There is no tag with the value of the name input.

Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

Terraform regular expression (regex) string.
Characters matching the regex will be removed from the ID elements.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.

Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.

Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs

metadata: Block status of the deployed release

Dependencies

Requirements

terraform, version: >= 1.3.0
aws, version: >= 4.9.0
helm, version: >= 2.0
kubernetes, version: >= 2.7.1, != 2.21.0

Providers

aws, version: >= 4.9.0

Modules

Name	Version	Source	Description
`eks`	1.5.0	`cloudposse/stack-config/yaml//modules/remote-state`	n/a
`iam_roles`	latest	`../../account-map/modules/iam-roles`	n/a
`karpenter`	0.10.1	`cloudposse/helm-release/aws`	Deploy Karpenter helm chart
`karpenter_crd`	0.10.1	`cloudposse/helm-release/aws`	Deploy karpenter-crd helm chart "karpenter-crd" can be installed as an independent helm chart to manage the lifecycle of Karpenter CRDs
`this`	0.25.0	`cloudposse/label/null`	n/a

Resources

The following resources are used by this module:

aws_cloudwatch_event_rule.interruption_handler (resource)
aws_cloudwatch_event_target.interruption_handler (resource)
aws_iam_policy.v1alpha (resource)
aws_iam_role_policy_attachment.v1alpha (resource)
aws_sqs_queue.interruption_handler (resource)
aws_sqs_queue_policy.interruption_handler (resource)

Data Sources

The following data sources are used by this module:

aws_eks_cluster_auth.eks (data source)
aws_iam_policy_document.interruption_handler (data source)
aws_partition.current (data source)

Usage​

Provision Karpenter on EKS cluster​

Provision Service-Linked Roles for EC2 Spot and EC2 Spot Fleet​

1. Provision EKS IAM Role for Nodes Launched by Karpenter​

VPC assumptions being made​

2. Provision karpenter component​

3. Provision karpenter-node-pool component​

Why use a separate component for NodePools?​

Node Interruption​

Interruption Handler vs. Termination Handler​

Custom Resource Definition (CRD) Management​

Troubleshooting​

References​

Variables​

Required Variables​

Optional Variables​

Context Variables​

Outputs​

Dependencies​

Requirements​

Providers​

Modules​

Resources​

Data Sources​

Related reading​

Usage

Provision Karpenter on EKS cluster

Provision Service-Linked Roles for EC2 Spot and EC2 Spot Fleet

1. Provision EKS IAM Role for Nodes Launched by Karpenter

VPC assumptions being made

2. Provision `karpenter` component

3. Provision `karpenter-node-pool` component

Why use a separate component for NodePools?

Node Interruption

Interruption Handler vs. Termination Handler

Custom Resource Definition (CRD) Management

Troubleshooting

References

Variables

Required Variables

Optional Variables

Context Variables

Outputs

Dependencies

Requirements

Providers

Modules

Resources

Data Sources

Related reading