# Amazon EKS Construct Library
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This construct library allows you to define [Amazon Elastic Container Service for Kubernetes (EKS)](https://aws.amazon.com/eks/) clusters.
In addition, the library also supports defining Kubernetes resource manifests within EKS clusters.

## Table Of Contents

* [Quick Start](#quick-start)
* [API Reference](https://docs.aws.amazon.com/cdk/api/latest/docs/aws-eks-readme.html)
* [Architectural Overview](#architectural-overview)
* [Provisioning clusters](#provisioning-clusters)
  * [Managed node groups](#managed-node-groups)
  * [Fargate Profiles](#fargate-profiles)
  * [Self-managed nodes](#self-managed-nodes)
  * [Endpoint Access](#endpoint-access)
  * [VPC Support](#vpc-support)
  * [Kubectl Support](#kubectl-support)
  * [ARM64 Support](#arm64-support)
  * [Masters Role](#masters-role)
  * [Encryption](#encryption)
* [Permissions and Security](#permissions-and-security)
* [Applying Kubernetes Resources](#applying-kubernetes-resources)
  * [Kubernetes Manifests](#kubernetes-manifests)
  * [Helm Charts](#helm-charts)
  * [CDK8s Charts](#cdk8s-charts)
* [Patching Kubernetes Resources](#patching-kubernetes-resources)
* [Querying Kubernetes Resources](#querying-kubernetes-resources)
* [Using existing clusters](#using-existing-clusters)
* [Known Issues and Limitations](#known-issues-and-limitations)

## Quick Start

This example defines an Amazon EKS cluster with the following configuration:

* Dedicated VPC with default configuration (Implicitly created using [ec2.Vpc](https://docs.aws.amazon.com/cdk/api/latest/docs/aws-ec2-readme.html#vpc))
* A Kubernetes pod with a container based on the [paulbouwer/hello-kubernetes](https://github.com/paulbouwer/hello-kubernetes) image.

```ts
// provisiong a cluster
const cluster = new eks.Cluster(this, 'hello-eks', {
  version: eks.KubernetesVersion.V1_19,
});

// apply a kubernetes manifest to the cluster
cluster.addManifest('mypod', {
  apiVersion: 'v1',
  kind: 'Pod',
  metadata: { name: 'mypod' },
  spec: {
    containers: [
      {
        name: 'hello',
        image: 'paulbouwer/hello-kubernetes:1.5',
        ports: [ { containerPort: 8080 } ]
      }
    ]
  }
});
```

In order to interact with your cluster through `kubectl`, you can use the `aws eks update-kubeconfig` [AWS CLI command](https://docs.aws.amazon.com/cli/latest/reference/eks/update-kubeconfig.html)
to configure your local kubeconfig. The EKS module will define a CloudFormation output in your stack which contains the command to run. For example:

```plaintext
Outputs:
ClusterConfigCommand43AAE40F = aws eks update-kubeconfig --name cluster-xxxxx --role-arn arn:aws:iam::112233445566:role/yyyyy
```

Execute the `aws eks update-kubeconfig ...` command in your terminal to create or update a local kubeconfig context:

```console
$ aws eks update-kubeconfig --name cluster-xxxxx --role-arn arn:aws:iam::112233445566:role/yyyyy
Added new context arn:aws:eks:rrrrr:112233445566:cluster/cluster-xxxxx to /home/boom/.kube/config
```

And now you can simply use `kubectl`:

```console
$ kubectl get all -n kube-system
NAME                           READY   STATUS    RESTARTS   AGE
pod/aws-node-fpmwv             1/1     Running   0          21m
pod/aws-node-m9htf             1/1     Running   0          21m
pod/coredns-5cb4fb54c7-q222j   1/1     Running   0          23m
pod/coredns-5cb4fb54c7-v9nxx   1/1     Running   0          23m
...
```

## Architectural Overview

The following is a qualitative diagram of the various possible components involved in the cluster deployment.

```text
 +-----------------------------------------------+               +-----------------+
 |                 EKS Cluster                   |    kubectl    |                 |
 |-----------------------------------------------|<-------------+| Kubectl Handler |
 |                                               |               |                 |
 |                                               |               +-----------------+
 | +--------------------+    +-----------------+ |
 | |                    |    |                 | |
 | | Managed Node Group |    | Fargate Profile | |               +-----------------+
 | |                    |    |                 | |               |                 |
 | +--------------------+    +-----------------+ |               | Cluster Handler |
 |                                               |               |                 |
 +-----------------------------------------------+               +-----------------+
    ^                                   ^                          +
    |                                   |                          |
    | connect self managed capacity     |                          | aws-sdk
    |                                   | create/update/delete     |
    +                                   |                          v
 +--------------------+                 +              +-------------------+
 |                    |                 --------------+| eks.amazonaws.com |
 | Auto Scaling Group |                                +-------------------+
 |                    |
 +--------------------+
```

In a nutshell:

* `EKS Cluster` - The cluster endpoint created by EKS.
* `Managed Node Group` - EC2 worker nodes managed by EKS.
* `Fargate Profile` - Fargate worker nodes managed by EKS.
* `Auto Scaling Group` - EC2 worker nodes managed by the user.
* `KubectlHandler` - Lambda function for invoking `kubectl` commands on the cluster - created by CDK.
* `ClusterHandler` - Lambda function for interacting with EKS API to manage the cluster lifecycle - created by CDK.

A more detailed breakdown of each is provided further down this README.

## Provisioning clusters

Creating a new cluster is done using the `Cluster` or `FargateCluster` constructs. The only required property is the kubernetes `version`.

```ts
new eks.Cluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
});
```

You can also use `FargateCluster` to provision a cluster that uses only fargate workers.

```ts
new eks.FargateCluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
});
```

> **NOTE: Only 1 cluster per stack is supported.** If you have a use-case for multiple clusters per stack, or would like to understand more about this limitation, see <https://github.com/aws/aws-cdk/issues/10073>.

Below you'll find a few important cluster configuration options. First of which is Capacity.
Capacity is the amount and the type of worker nodes that are available to the cluster for deploying resources. Amazon EKS offers 3 ways of configuring capacity, which you can combine as you like:

### Managed node groups

Amazon EKS managed node groups automate the provisioning and lifecycle management of nodes (Amazon EC2 instances) for Amazon EKS Kubernetes clusters.
With Amazon EKS managed node groups, you don’t need to separately provision or register the Amazon EC2 instances that provide compute capacity to run your Kubernetes applications. You can create, update, or terminate nodes for your cluster with a single operation. Nodes run using the latest Amazon EKS optimized AMIs in your AWS account while node updates and terminations gracefully drain nodes to ensure that your applications stay available.

> For more details visit [Amazon EKS Managed Node Groups](https://docs.aws.amazon.com/eks/latest/userguide/managed-node-groups.html).

**Managed Node Groups are the recommended way to allocate cluster capacity.**

By default, this library will allocate a managed node group with 2 *m5.large* instances (this instance type suits most common use-cases, and is good value for money).

At cluster instantiation time, you can customize the number of instances and their type:

```ts
new eks.Cluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
  defaultCapacity: 5,
  defaultCapacityInstance: ec2.InstanceType.of(ec2.InstanceClass.M5, ec2.InstanceSize.SMALL),
});
```

To access the node group that was created on your behalf, you can use `cluster.defaultNodegroup`.

Additional customizations are available post instantiation. To apply them, set the default capacity to 0, and use the `cluster.addNodegroupCapacity` method:

```ts
const cluster = new eks.Cluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
  defaultCapacity: 0,
});

cluster.addNodegroupCapacity('custom-node-group', {
  instanceTypes: [new ec2.InstanceType('m5.large')],
  minSize: 4,
  diskSize: 100,
  amiType: eks.NodegroupAmiType.AL2_X86_64_GPU,
  ...
});
```

#### Spot Instances Support

Use `capacityType` to create managed node groups comprised of spot instances. To maximize the availability of your applications while using
Spot Instances, we recommend that you configure a Spot managed node group to use multiple instance types with the `instanceTypes` property.

> For more details visit [Managed node group capacity types](https://docs.aws.amazon.com/eks/latest/userguide/managed-node-groups.html#managed-node-group-capacity-types).


```ts
cluster.addNodegroupCapacity('extra-ng-spot', {
  instanceTypes: [
    new ec2.InstanceType('c5.large'),
    new ec2.InstanceType('c5a.large'),
    new ec2.InstanceType('c5d.large'),
  ],
  minSize: 3,
  capacityType: eks.CapacityType.SPOT,
});

```

#### Launch Template Support

You can specify a launch template that the node group will use. For example, this can be useful if you want to use
a custom AMI or add custom user data.

When supplying a custom user data script, it must be encoded in the MIME multi-part archive format, since Amazon EKS merges with its own user data. Visit the [Launch Template Docs](https://docs.aws.amazon.com/eks/latest/userguide/launch-templates.html#launch-template-user-data)
for mode details.

```ts
const userData = `MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="==MYBOUNDARY=="

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

#!/bin/bash
echo "Running custom user data script"

--==MYBOUNDARY==--\\
`;
const lt = new ec2.CfnLaunchTemplate(this, 'LaunchTemplate', {
  launchTemplateData: {
    instanceType: 't3.small',
    userData: Fn.base64(userData),
  },
});
cluster.addNodegroupCapacity('extra-ng', {
  launchTemplateSpec: {
    id: lt.ref,
    version: lt.attrLatestVersionNumber,
  },
});

```

Note that when using a custom AMI, Amazon EKS doesn't merge any user data. Which means you do not need the multi-part encoding. and are responsible for supplying the required bootstrap commands for nodes to join the cluster.
In the following example, `/ect/eks/bootstrap.sh` from the AMI will be used to bootstrap the node.

```ts
const userData = ec2.UserData.forLinux();
userData.addCommands(
  'set -o xtrace',
  `/etc/eks/bootstrap.sh ${cluster.clusterName}`,
);
const lt = new ec2.CfnLaunchTemplate(this, 'LaunchTemplate', {
  launchTemplateData: {
    imageId: 'some-ami-id', // custom AMI
    instanceType: 't3.small',
    userData: Fn.base64(userData.render()),
  },
});
cluster.addNodegroupCapacity('extra-ng', {
  launchTemplateSpec: {
    id: lt.ref,
    version: lt.attrLatestVersionNumber,
  },
});
```

You may specify one `instanceType` in the launch template or multiple `instanceTypes` in the node group, **but not both**.

> For more details visit [Launch Template Support](https://docs.aws.amazon.com/eks/latest/userguide/launch-templates.html).

Graviton 2 instance types are supported including `c6g`, `m6g`, `r6g` and `t4g`.

### Fargate profiles

AWS Fargate is a technology that provides on-demand, right-sized compute
capacity for containers. With AWS Fargate, you no longer have to provision,
configure, or scale groups of virtual machines to run containers. This removes
the need to choose server types, decide when to scale your node groups, or
optimize cluster packing.

You can control which pods start on Fargate and how they run with Fargate
Profiles, which are defined as part of your Amazon EKS cluster.

See [Fargate Considerations](https://docs.aws.amazon.com/eks/latest/userguide/fargate.html#fargate-considerations) in the AWS EKS User Guide.

You can add Fargate Profiles to any EKS cluster defined in your CDK app
through the `addFargateProfile()` method. The following example adds a profile
that will match all pods from the "default" namespace:

```ts
cluster.addFargateProfile('MyProfile', {
  selectors: [ { namespace: 'default' } ]
});
```

You can also directly use the `FargateProfile` construct to create profiles under different scopes:

```ts
new eks.FargateProfile(scope, 'MyProfile', {
  cluster,
  ...
});
```

To create an EKS cluster that **only** uses Fargate capacity, you can use `FargateCluster`.
The following code defines an Amazon EKS cluster with a default Fargate Profile that matches all pods from the "kube-system" and "default" namespaces. It is also configured to [run CoreDNS on Fargate](https://docs.aws.amazon.com/eks/latest/userguide/fargate-getting-started.html#fargate-gs-coredns).

```ts
const cluster = new eks.FargateCluster(this, 'MyCluster', {
  version: eks.KubernetesVersion.V1_19,
});
```

**NOTE**: Classic Load Balancers and Network Load Balancers are not supported on
pods running on Fargate. For ingress, we recommend that you use the [ALB Ingress
Controller](https://docs.aws.amazon.com/eks/latest/userguide/alb-ingress.html)
on Amazon EKS (minimum version v1.1.4).

### Self-managed nodes

Another way of allocating capacity to an EKS cluster is by using self-managed nodes.
EC2 instances that are part of the auto-scaling group will serve as worker nodes for the cluster.
This type of capacity is also commonly referred to as *EC2 Capacity** or *EC2 Nodes*.

For a detailed overview please visit [Self Managed Nodes](https://docs.aws.amazon.com/eks/latest/userguide/worker.html).

Creating an auto-scaling group and connecting it to the cluster is done using the `cluster.addAutoScalingGroupCapacity` method:

```ts
cluster.addAutoScalingGroupCapacity('frontend-nodes', {
  instanceType: new ec2.InstanceType('t2.medium'),
  minCapacity: 3,
  vpcSubnets: { subnetType: ec2.SubnetType.PUBLIC }
});
```

To connect an already initialized auto-scaling group, use the `cluster.connectAutoScalingGroupCapacity()` method:

```ts
const asg = new ec2.AutoScalingGroup(...);
cluster.connectAutoScalingGroupCapacity(asg);
```

In both cases, the [cluster security group](https://docs.aws.amazon.com/eks/latest/userguide/sec-group-reqs.html#cluster-sg) will be automatically attached to
the auto-scaling group, allowing for traffic to flow freely between managed and self-managed nodes.

> **Note:** The default `updateType` for auto-scaling groups does not replace existing nodes. Since security groups are determined at launch time, self-managed nodes that were provisioned with version `1.78.0` or lower, will not be updated.
> To apply the new configuration on all your self-managed nodes, you'll need to replace the nodes using the `UpdateType.REPLACING_UPDATE` policy for the [`updateType`](https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-autoscaling.AutoScalingGroup.html#updatetypespan-classapi-icon-api-icon-deprecated-titlethis-api-element-is-deprecated-its-use-is-not-recommended%EF%B8%8Fspan) property.

You can customize the [/etc/eks/boostrap.sh](https://github.com/awslabs/amazon-eks-ami/blob/master/files/bootstrap.sh) script, which is responsible
for bootstrapping the node to the EKS cluster. For example, you can use `kubeletExtraArgs` to add custom node labels or taints.

```ts
cluster.addAutoScalingGroupCapacity('spot', {
  instanceType: new ec2.InstanceType('t3.large'),
  minCapacity: 2,
  bootstrapOptions: {
    kubeletExtraArgs: '--node-labels foo=bar,goo=far',
    awsApiRetryAttempts: 5
  }
});
```

To disable bootstrapping altogether (i.e. to fully customize user-data), set `bootstrapEnabled` to `false`.
You can also configure the cluster to use an auto-scaling group as the default capacity:

```ts
cluster = new eks.Cluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
  defaultCapacityType: eks.DefaultCapacityType.EC2,
});
```

This will allocate an auto-scaling group with 2 *m5.large* instances (this instance type suits most common use-cases, and is good value for money).
To access the `AutoScalingGroup` that was created on your behalf, you can use `cluster.defaultCapacity`.
You can also independently create an `AutoScalingGroup` and connect it to the cluster using the `cluster.connectAutoScalingGroupCapacity` method:

```ts
const asg = new ec2.AutoScalingGroup(...)
cluster.connectAutoScalingGroupCapacity(asg);
```

This will add the necessary user-data to access the apiserver and configure all connections, roles, and tags needed for the instances in the auto-scaling group to properly join the cluster.

#### Spot Instances

When using self-managed nodes, you can configure the capacity to use spot instances, greatly reducing capacity cost.
To enable spot capacity, use the `spotPrice` property:

```ts
cluster.addAutoScalingGroupCapacity('spot', {
  spotPrice: '0.1094',
  instanceType: new ec2.InstanceType('t3.large'),
  maxCapacity: 10
});
```

> Spot instance nodes will be labeled with `lifecycle=Ec2Spot` and tainted with `PreferNoSchedule`.

The [AWS Node Termination Handler](https://github.com/aws/aws-node-termination-handler) `DaemonSet` will be
installed from [Amazon EKS Helm chart repository](https://github.com/aws/eks-charts/tree/master/stable/aws-node-termination-handler) on these nodes.
The termination handler ensures that the Kubernetes control plane responds appropriately to events that
can cause your EC2 instance to become unavailable, such as [EC2 maintenance events](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/monitoring-instances-status-check_sched.html)
and [EC2 Spot interruptions](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-interruptions.html) and helps gracefully stop all pods running on spot nodes that are about to be
terminated.

> Handler Version: [1.7.0](https://github.com/aws/aws-node-termination-handler/releases/tag/v1.7.0)
>
> Chart Version: [0.9.5](https://github.com/aws/eks-charts/blob/v0.0.28/stable/aws-node-termination-handler/Chart.yaml)

To disable the installation of the termination handler, set the `spotInterruptHandler` property to `false`. This applies both to `addAutoScalingGroupCapacity` and `connectAutoScalingGroupCapacity`.

#### Bottlerocket

[Bottlerocket](https://aws.amazon.com/bottlerocket/) is a Linux-based open-source operating system that is purpose-built by Amazon Web Services for running containers on virtual machines or bare metal hosts.
At this moment, `Bottlerocket` is only supported when using self-managed auto-scaling groups.

> **NOTICE**: Bottlerocket is only available in [some supported AWS regions](https://github.com/bottlerocket-os/bottlerocket/blob/develop/QUICKSTART-EKS.md#finding-an-ami).

The following example will create an auto-scaling group of 2 `t3.small` Linux instances running with the `Bottlerocket` AMI.

```ts
cluster.addAutoScalingGroupCapacity('BottlerocketNodes', {
  instanceType: new ec2.InstanceType('t3.small'),
  minCapacity:  2,
  machineImageType: eks.MachineImageType.BOTTLEROCKET
});
```

The specific Bottlerocket AMI variant will be auto selected according to the k8s version for the `x86_64` architecture.
For example, if the Amazon EKS cluster version is `1.17`, the Bottlerocket AMI variant will be auto selected as
`aws-k8s-1.17` behind the scene.

> See [Variants](https://github.com/bottlerocket-os/bottlerocket/blob/develop/README.md#variants) for more details.

Please note Bottlerocket does not allow to customize bootstrap options and `bootstrapOptions` properties is not supported when you create the `Bottlerocket` capacity.

### Endpoint Access

When you create a new cluster, Amazon EKS creates an endpoint for the managed Kubernetes API server that you use to communicate with your cluster (using Kubernetes management tools such as `kubectl`)

By default, this API server endpoint is public to the internet, and access to the API server is secured using a combination of
AWS Identity and Access Management (IAM) and native Kubernetes [Role Based Access Control](https://kubernetes.io/docs/reference/access-authn-authz/rbac/) (RBAC).

You can configure the [cluster endpoint access](https://docs.aws.amazon.com/eks/latest/userguide/cluster-endpoint.html) by using the `endpointAccess` property:

```ts
const cluster = new eks.Cluster(this, 'hello-eks', {
  version: eks.KubernetesVersion.V1_19,
  endpointAccess: eks.EndpointAccess.PRIVATE // No access outside of your VPC.
});
```

The default value is `eks.EndpointAccess.PUBLIC_AND_PRIVATE`. Which means the cluster endpoint is accessible from outside of your VPC, but worker node traffic and `kubectl` commands issued by this library stay within your VPC.

### VPC Support

You can specify the VPC of the cluster using the `vpc` and `vpcSubnets` properties:

```ts
const vpc = new ec2.Vpc(this, 'Vpc');

new eks.Cluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
  vpc,
  vpcSubnets: [{ subnetType: ec2.SubnetType.PRIVATE }]
});
```

> Note: Isolated VPCs (i.e with no internet access) are not currently supported. See https://github.com/aws/aws-cdk/issues/12171

If you do not specify a VPC, one will be created on your behalf, which you can then access via `cluster.vpc`. The cluster VPC will be associated to any EKS managed capacity (i.e Managed Node Groups and Fargate Profiles).

If you allocate self managed capacity, you can specify which subnets should the auto-scaling group use:

```ts
const vpc = new ec2.Vpc(this, 'Vpc');
cluster.addAutoScalingGroupCapacity('nodes', {
  vpcSubnets: { subnets: vpc.privateSubnets }
});
```

There are two additional components you might want to provision within the VPC.

#### Kubectl Handler

The `KubectlHandler` is a Lambda function responsible to issuing `kubectl` and `helm` commands against the cluster when you add resource manifests to the cluster.

The handler association to the VPC is derived from the `endpointAccess` configuration. The rule of thumb is: *If the cluster VPC can be associated, it will be*.

Breaking this down, it means that if the endpoint exposes private access (via `EndpointAccess.PRIVATE` or `EndpointAccess.PUBLIC_AND_PRIVATE`), and the VPC contains **private** subnets, the Lambda function will be provisioned inside the VPC and use the private subnets to interact with the cluster. This is the common use-case.

If the endpoint does not expose private access (via `EndpointAccess.PUBLIC`) **or** the VPC does not contain private subnets, the function will not be provisioned within the VPC.

#### Cluster Handler

The `ClusterHandler` is a Lambda function responsible to interact with the EKS API in order to control the cluster lifecycle. To provision this function inside the VPC, set the `placeClusterHandlerInVpc` property to `true`. This will place the function inside the private subnets of the VPC based on the selection strategy specified in the [`vpcSubnets`](https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-eks.Cluster.html#vpcsubnetsspan-classapi-icon-api-icon-experimental-titlethis-api-element-is-experimental-it-may-change-without-noticespan) property.

You can configure the environment of this function by specifying it at cluster instantiation. For example, this can be useful in order to configure an http proxy:

```ts
const cluster = new eks.Cluster(this, 'hello-eks', {
  version: eks.KubernetesVersion.V1_19,
  clusterHandlerEnvironment: {
    'http_proxy': 'http://proxy.myproxy.com'
  }
});
```

### Kubectl Support

The resources are created in the cluster by running `kubectl apply` from a python lambda function.

#### Environment

You can configure the environment of this function by specifying it at cluster instantiation. For example, this can be useful in order to configure an http proxy:

```ts
const cluster = new eks.Cluster(this, 'hello-eks', {
  version: eks.KubernetesVersion.V1_19,
  kubectlEnvironment: {
    'http_proxy': 'http://proxy.myproxy.com'
  }
});
```

#### Runtime

The kubectl handler uses `kubectl`, `helm` and the `aws` CLI in order to
interact with the cluster. These are bundled into AWS Lambda layers included in
the `@aws-cdk/lambda-layer-awscli` and `@aws-cdk/lambda-layer-kubectl` modules.

You can specify a custom `lambda.LayerVersion` if you wish to use a different
version of these tools. The handler expects the layer to include the following
three executables:

```text
helm/helm
kubectl/kubectl
awscli/aws
```

See more information in the
[Dockerfile](https://github.com/aws/aws-cdk/tree/master/packages/%40aws-cdk/lambda-layer-awscli/layer) for @aws-cdk/lambda-layer-awscli
and the
[Dockerfile](https://github.com/aws/aws-cdk/tree/master/packages/%40aws-cdk/lambda-layer-kubectl/layer) for @aws-cdk/lambda-layer-kubectl.

```ts
const layer = new lambda.LayerVersion(this, 'KubectlLayer', {
  code: lambda.Code.fromAsset('layer.zip'),
});
```

Now specify when the cluster is defined:

```ts
const cluster = new eks.Cluster(this, 'MyCluster', {
  kubectlLayer: layer,
});

// or
const cluster = eks.Cluster.fromClusterAttributes(this, 'MyCluster', {
  kubectlLayer: layer,
});
```

#### Memory

By default, the kubectl provider is configured with 1024MiB of memory. You can use the `kubectlMemory` option to specify the memory size for the AWS Lambda function:

```ts
import { Size } from '@aws-cdk/core';

new eks.Cluster(this, 'MyCluster', {
  kubectlMemory: Size.gibibytes(4)
});

// or
eks.Cluster.fromClusterAttributes(this, 'MyCluster', {
  kubectlMemory: Size.gibibytes(4)
});
```

### ARM64 Support

Instance types with `ARM64` architecture are supported in both managed nodegroup and self-managed capacity. Simply specify an ARM64 `instanceType` (such as `m6g.medium`), and the latest
Amazon Linux 2 AMI for ARM64 will be automatically selected.

```ts
// add a managed ARM64 nodegroup
cluster.addNodegroupCapacity('extra-ng-arm', {
  instanceTypes: [new ec2.InstanceType('m6g.medium')],
  minSize: 2,
});

// add a self-managed ARM64 nodegroup
cluster.addAutoScalingGroupCapacity('self-ng-arm', {
  instanceType: new ec2.InstanceType('m6g.medium'),
  minCapacity: 2,
})
```

### Masters Role

When you create a cluster, you can specify a `mastersRole`. The `Cluster` construct will associate this role with the `system:masters` [RBAC](https://kubernetes.io/docs/reference/access-authn-authz/rbac/) group, giving it super-user access to the cluster.

```ts
const role = new iam.Role(...);
new eks.Cluster(this, 'HelloEKS', {
  version: eks.KubernetesVersion.V1_19,
  mastersRole: role,
});
```

If you do not specify it, a default role will be created on your behalf, that can be assumed by anyone in the account with `sts:AssumeRole` permissions for this role.

This is the role you see as part of the stack outputs mentioned in the [Quick Start](#quick-start).

```console
$ aws eks update-kubeconfig --name cluster-xxxxx --role-arn arn:aws:iam::112233445566:role/yyyyy
Added new context arn:aws:eks:rrrrr:112233445566:cluster/cluster-xxxxx to /home/boom/.kube/config
```

### Encryption

When you create an Amazon EKS cluster, envelope encryption of Kubernetes secrets using the AWS Key Management Service (AWS KMS) can be enabled.
The documentation on [creating a cluster](https://docs.aws.amazon.com/eks/latest/userguide/create-cluster.html)
can provide more details about the customer master key (CMK) that can be used for the encryption.

You can use the `secretsEncryptionKey` to configure which key the cluster will use to encrypt Kubernetes secrets. By default, an AWS Managed key will be used.

> This setting can only be specified when the cluster is created and cannot be updated.

```ts
const secretsKey = new kms.Key(this, 'SecretsKey');
const cluster = new eks.Cluster(this, 'MyCluster', {
  secretsEncryptionKey: secretsKey,
  // ...
});
```

You can also use a similiar configuration for running a cluster built using the FargateCluster construct.

```ts
const secretsKey = new kms.Key(this, 'SecretsKey');
const cluster = new eks.FargateCluster(this, 'MyFargateCluster', {
  secretsEncryptionKey: secretsKey
});
```

The Amazon Resource Name (ARN) for that CMK can be retrieved.

```ts
const clusterEncryptionConfigKeyArn = cluster.clusterEncryptionConfigKeyArn;
```

## Permissions and Security

Amazon EKS provides several mechanism of securing the cluster and granting permissions to specific IAM users and roles.

### AWS IAM Mapping

As described in the [Amazon EKS User Guide](https://docs.aws.amazon.com/en_us/eks/latest/userguide/add-user-role.html), you can map AWS IAM users and roles to [Kubernetes Role-based access control (RBAC)](https://kubernetes.io/docs/reference/access-authn-authz/rbac).

The Amazon EKS construct manages the *aws-auth* `ConfigMap` Kubernetes resource on your behalf and exposes an API through the `cluster.awsAuth` for mapping
users, roles and accounts.

Furthermore, when auto-scaling group capacity is added to the cluster, the IAM instance role of the auto-scaling group will be automatically mapped to RBAC so nodes can connect to the cluster. No manual mapping is required.

For example, let's say you want to grant an IAM user administrative privileges on your cluster:

```ts
const adminUser = new iam.User(this, 'Admin');
cluster.awsAuth.addUserMapping(adminUser, { groups: [ 'system:masters' ]});
```

A convenience method for mapping a role to the `system:masters` group is also available:

```ts
cluster.awsAuth.addMastersRole(role)
```

### Cluster Security Group

When you create an Amazon EKS cluster, a [cluster security group](https://docs.aws.amazon.com/eks/latest/userguide/sec-group-reqs.html)
is automatically created as well. This security group is designed to allow all traffic from the control plane and managed node groups to flow freely
between each other.

The ID for that security group can be retrieved after creating the cluster.

```ts
const clusterSecurityGroupId = cluster.clusterSecurityGroupId;
```

### Node SSH Access

If you want to be able to SSH into your worker nodes, you must already have an SSH key in the region you're connecting to and pass it when
you add capacity to the cluster. You must also be able to connect to the hosts (meaning they must have a public IP and you
should be allowed to connect to them on port 22):

See [SSH into nodes](test/example.ssh-into-nodes.lit.ts) for a code example.

If you want to SSH into nodes in a private subnet, you should set up a bastion host in a public subnet. That setup is recommended, but is
unfortunately beyond the scope of this documentation.

### Service Accounts

With services account you can provide Kubernetes Pods access to AWS resources.

```ts
// add service account
const sa = cluster.addServiceAccount('MyServiceAccount');

const bucket = new Bucket(this, 'Bucket');
bucket.grantReadWrite(serviceAccount);

const mypod = cluster.addManifest('mypod', {
  apiVersion: 'v1',
  kind: 'Pod',
  metadata: { name: 'mypod' },
  spec: {
    serviceAccountName: sa.serviceAccountName
    containers: [
      {
        name: 'hello',
        image: 'paulbouwer/hello-kubernetes:1.5',
        ports: [ { containerPort: 8080 } ],

      }
    ]
  }
});

// create the resource after the service account.
mypod.node.addDependency(sa);

// print the IAM role arn for this service account
new cdk.CfnOutput(this, 'ServiceAccountIamRole', { value: sa.role.roleArn })
```

Note that using `sa.serviceAccountName` above **does not** translate into a resource dependency.
This is why an explicit dependency is needed. See <https://github.com/aws/aws-cdk/issues/9910> for more details.

You can also add service accounts to existing clusters.
To do so, pass the `openIdConnectProvider` property when you import the cluster into the application.

```ts
// you can import an existing provider
const provider = eks.OpenIdConnectProvider.fromOpenIdConnectProviderArn(this, 'Provider', 'arn:aws:iam::123456:oidc-provider/oidc.eks.eu-west-1.amazonaws.com/id/AB123456ABC');

// or create a new one using an existing issuer url
const provider = new eks.OpenIdConnectProvider(this, 'Provider', issuerUrl);

const cluster = eks.Cluster.fromClusterAttributes({
  clusterName: 'Cluster',
  openIdConnectProvider: provider,
  kubectlRoleArn: 'arn:aws:iam::123456:role/service-role/k8sservicerole',
});

const sa = cluster.addServiceAccount('MyServiceAccount');

const bucket = new Bucket(this, 'Bucket');
bucket.grantReadWrite(serviceAccount);

// ...
```

Note that adding service accounts requires running `kubectl` commands against the cluster.
This means you must also pass the `kubectlRoleArn` when importing the cluster.
See [Using existing Clusters](https://github.com/aws/aws-cdk/tree/master/packages/@aws-cdk/aws-eks#using-existing-clusters).

## Applying Kubernetes Resources

The library supports several popular resource deployment mechanisms, among which are:

### Kubernetes Manifests

The `KubernetesManifest` construct or `cluster.addManifest` method can be used
to apply Kubernetes resource manifests to this cluster.

> When using `cluster.addManifest`, the manifest construct is defined within the cluster's stack scope. If the manifest contains
> attributes from a different stack which depend on the cluster stack, a circular dependency will be created and you will get a synth time error.
> To avoid this, directly use `new KubernetesManifest` to create the manifest in the scope of the other stack.

The following examples will deploy the [paulbouwer/hello-kubernetes](https://github.com/paulbouwer/hello-kubernetes)
service on the cluster:

```ts
const appLabel = { app: "hello-kubernetes" };

const deployment = {
  apiVersion: "apps/v1",
  kind: "Deployment",
  metadata: { name: "hello-kubernetes" },
  spec: {
    replicas: 3,
    selector: { matchLabels: appLabel },
    template: {
      metadata: { labels: appLabel },
      spec: {
        containers: [
          {
            name: "hello-kubernetes",
            image: "paulbouwer/hello-kubernetes:1.5",
            ports: [ { containerPort: 8080 } ]
          }
        ]
      }
    }
  }
};

const service = {
  apiVersion: "v1",
  kind: "Service",
  metadata: { name: "hello-kubernetes" },
  spec: {
    type: "LoadBalancer",
    ports: [ { port: 80, targetPort: 8080 } ],
    selector: appLabel
  }
};

// option 1: use a construct
new KubernetesManifest(this, 'hello-kub', {
  cluster,
  manifest: [ deployment, service ]
});

// or, option2: use `addManifest`
cluster.addManifest('hello-kub', service, deployment);
```

#### Adding resources from a URL

The following example will deploy the resource manifest hosting on remote server:

```ts
import * as yaml from 'js-yaml';
import * as request from 'sync-request';

const manifestUrl = 'https://url/of/manifest.yaml';
const manifest = yaml.safeLoadAll(request('GET', manifestUrl).getBody());
cluster.addManifest('my-resource', ...manifest);
```

#### Dependencies

There are cases where Kubernetes resources must be deployed in a specific order.
For example, you cannot define a resource in a Kubernetes namespace before the
namespace was created.

You can represent dependencies between `KubernetesManifest`s using
`resource.node.addDependency()`:

```ts
const namespace = cluster.addManifest('my-namespace', {
  apiVersion: 'v1',
  kind: 'Namespace',
  metadata: { name: 'my-app' }
});

const service = cluster.addManifest('my-service', {
  metadata: {
    name: 'myservice',
    namespace: 'my-app'
  },
  spec: // ...
});

service.node.addDependency(namespace); // will apply `my-namespace` before `my-service`.
```

**NOTE:** when a `KubernetesManifest` includes multiple resources (either directly
or through `cluster.addManifest()`) (e.g. `cluster.addManifest('foo', r1, r2,
r3,...)`), these resources will be applied as a single manifest via `kubectl`
and will be applied sequentially (the standard behavior in `kubectl`).

---

Since Kubernetes manifests are implemented as CloudFormation resources in the
CDK. This means that if the manifest is deleted from your code (or the stack is
deleted), the next `cdk deploy` will issue a `kubectl delete` command and the
Kubernetes resources in that manifest will be deleted.

#### Resource Pruning

When a resource is deleted from a Kubernetes manifest, the EKS module will
automatically delete these resources by injecting a _prune label_ to all
manifest resources. This label is then passed to [`kubectl apply --prune`].

[`kubectl apply --prune`]: https://kubernetes.io/docs/tasks/manage-kubernetes-objects/declarative-config/#alternative-kubectl-apply-f-directory-prune-l-your-label

Pruning is enabled by default but can be disabled through the `prune` option
when a cluster is defined:

```ts
new Cluster(this, 'MyCluster', {
  prune: false
});
```

#### Manifests Validation

The `kubectl` CLI supports applying a manifest by skipping the validation.
This can be accomplished by setting the `skipValidation` flag to `true` in the `KubernetesManifest` props.

```ts
new eks.KubernetesManifest(this, 'HelloAppWithoutValidation', {
  cluster: this.cluster,
  manifest: [ deployment, service ],
  skipValidation: true,
});
```

### Helm Charts

The `HelmChart` construct or `cluster.addHelmChart` method can be used
to add Kubernetes resources to this cluster using Helm.

> When using `cluster.addHelmChart`, the manifest construct is defined within the cluster's stack scope. If the manifest contains
> attributes from a different stack which depend on the cluster stack, a circular dependency will be created and you will get a synth time error.
> To avoid this, directly use `new HelmChart` to create the chart in the scope of the other stack.

The following example will install the [NGINX Ingress Controller](https://kubernetes.github.io/ingress-nginx/) to your cluster using Helm.

```ts
// option 1: use a construct
new HelmChart(this, 'NginxIngress', {
  cluster,
  chart: 'nginx-ingress',
  repository: 'https://helm.nginx.com/stable',
  namespace: 'kube-system'
});

// or, option2: use `addHelmChart`
cluster.addHelmChart('NginxIngress', {
  chart: 'nginx-ingress',
  repository: 'https://helm.nginx.com/stable',
  namespace: 'kube-system'
});
```

Helm charts will be installed and updated using `helm upgrade --install`, where a few parameters
are being passed down (such as `repo`, `values`, `version`, `namespace`, `wait`, `timeout`, etc).
This means that if the chart is added to CDK with the same release name, it will try to update
the chart in the cluster.

Helm charts are implemented as CloudFormation resources in CDK.
This means that if the chart is deleted from your code (or the stack is
deleted), the next `cdk deploy` will issue a `helm uninstall` command and the
Helm chart will be deleted.

When there is no `release` defined, a unique ID will be allocated for the release based
on the construct path.

By default, all Helm charts will be installed concurrently. In some cases, this
could cause race conditions where two Helm charts attempt to deploy the same
resource or if Helm charts depend on each other. You can use
`chart.node.addDependency()` in order to declare a dependency order between
charts:

```ts
const chart1 = cluster.addHelmChart(...);
const chart2 = cluster.addHelmChart(...);

chart2.node.addDependency(chart1);
```

#### CDK8s Charts

[CDK8s](https://cdk8s.io/) is an open-source library that enables Kubernetes manifest authoring using familiar programming languages. It is founded on the same technologies as the AWS CDK, such as [`constructs`](https://github.com/aws/constructs) and [`jsii`](https://github.com/aws/jsii).

> To learn more about cdk8s, visit the [Getting Started](https://github.com/awslabs/cdk8s/tree/master/docs/getting-started) tutorials.

The EKS module natively integrates with cdk8s and allows you to apply cdk8s charts on AWS EKS clusters via the `cluster.addCdk8sChart` method.

In addition to `cdk8s`, you can also use [`cdk8s+`](https://github.com/awslabs/cdk8s/tree/master/packages/cdk8s-plus), which provides higher level abstraction for the core kubernetes api objects.
You can think of it like the `L2` constructs for Kubernetes. Any other `cdk8s` based libraries are also supported, for example [`cdk8s-debore`](https://github.com/toricls/cdk8s-debore).

To get started, add the following dependencies to your `package.json` file:

```json
"dependencies": {
  "cdk8s": "0.30.0",
  "cdk8s-plus": "0.30.0",
  "constructs": "3.0.4"
}
```

> Note that the version of `cdk8s` must be `>=0.30.0`.

Similarly to how you would create a stack by extending `@aws-cdk/core.Stack`, we recommend you create a chart of your own that extends `cdk8s.Chart`,
and add your kubernetes resources to it. You can use `aws-cdk` construct attributes and properties inside your `cdk8s` construct freely.

In this example we create a chart that accepts an `s3.Bucket` and passes its name to a kubernetes pod as an environment variable.

Notice that the chart must accept a `constructs.Construct` type as its scope, not an `@aws-cdk/core.Construct` as you would normally use.
For this reason, to avoid possible confusion, we will create the chart in a separate file:

`+ my-chart.ts`

```ts
import * as s3 from '@aws-cdk/aws-s3';
import * as constructs from 'constructs';
import * as cdk8s from 'cdk8s';
import * as kplus from 'cdk8s-plus';

export interface MyChartProps {
  readonly bucket: s3.Bucket;
}

export class MyChart extends cdk8s.Chart {
  constructor(scope: constructs.Construct, id: string, props: MyChartProps) {
    super(scope, id);

    new kplus.Pod(this, 'Pod', {
      spec: {
        containers: [
          new kplus.Container({
            image: 'my-image',
            env: {
              BUCKET_NAME: kplus.EnvValue.fromValue(props.bucket.bucketName),
            },
          }),
        ],
      },
    });
  }
}
```

Then, in your AWS CDK app:

```ts
import * as s3 from '@aws-cdk/aws-s3';
import * as cdk8s from 'cdk8s';
import { MyChart } from './my-chart';

// some bucket..
const bucket = new s3.Bucket(this, 'Bucket');

// create a cdk8s chart and use `cdk8s.App` as the scope.
const myChart = new MyChart(new cdk8s.App(), 'MyChart', { bucket });

// add the cdk8s chart to the cluster
cluster.addCdk8sChart('my-chart', myChart);
```

##### Custom CDK8s Constructs

You can also compose a few stock `cdk8s+` constructs into your own custom construct. However, since mixing scopes between `aws-cdk` and `cdk8s` is currently not supported, the `Construct` class
you'll need to use is the one from the [`constructs`](https://github.com/aws/constructs) module, and not from `@aws-cdk/core` like you normally would.
This is why we used `new cdk8s.App()` as the scope of the chart above.

```ts
import * as constructs from 'constructs';
import * as cdk8s from 'cdk8s';
import * as kplus from 'cdk8s-plus';

export interface LoadBalancedWebService {
  readonly port: number;
  readonly image: string;
  readonly replicas: number;
}

export class LoadBalancedWebService extends constructs.Construct {
  constructor(scope: constructs.Construct, id: string, props: LoadBalancedWebService) {
    super(scope, id);

    const deployment = new kplus.Deployment(chart, 'Deployment', {
      spec: {
        replicas: props.replicas,
        podSpecTemplate: {
          containers: [ new kplus.Container({ image: props.image }) ]
        }
      },
    });

    deployment.expose({port: props.port, serviceType: kplus.ServiceType.LOAD_BALANCER})

  }
}
```

##### Manually importing k8s specs and CRD's

If you find yourself unable to use `cdk8s+`, or just like to directly use the `k8s` native objects or CRD's, you can do so by manually importing them using the `cdk8s-cli`.

See [Importing kubernetes objects](https://github.com/awslabs/cdk8s/tree/master/packages/cdk8s-cli#import) for detailed instructions.

## Patching Kubernetes Resources

The `KubernetesPatch` construct can be used to update existing kubernetes
resources. The following example can be used to patch the `hello-kubernetes`
deployment from the example above with 5 replicas.

```ts
new KubernetesPatch(this, 'hello-kub-deployment-label', {
  cluster,
  resourceName: "deployment/hello-kubernetes",
  applyPatch: { spec: { replicas: 5 } },
  restorePatch: { spec: { replicas: 3 } }
})
```

## Querying Kubernetes Resources

The `KubernetesObjectValue` construct can be used to query for information about kubernetes objects,
and use that as part of your CDK application.

For example, you can fetch the address of a [`LoadBalancer`](https://kubernetes.io/docs/concepts/services-networking/service/#loadbalancer) type service:

```ts
// query the load balancer address
const myServiceAddress = new KubernetesObjectValue(this, 'LoadBalancerAttribute', {
  cluster: cluster,
  objectType: 'service',
  objectName: 'my-service',
  jsonPath: '.status.loadBalancer.ingress[0].hostname', // https://kubernetes.io/docs/reference/kubectl/jsonpath/
});

// pass the address to a lambda function
const proxyFunction = new lambda.Function(this, 'ProxyFunction', {
  ...
  environment: {
    myServiceAddress: myServiceAddress.value
  },
})
```

Specifically, since the above use-case is quite common, there is an easier way to access that information:

```ts
const loadBalancerAddress = cluster.getServiceLoadBalancerAddress('my-service');
```

## Using existing clusters

The Amazon EKS library allows defining Kubernetes resources such as [Kubernetes
manifests](#kubernetes-resources) and [Helm charts](#helm-charts) on clusters
that are not defined as part of your CDK app.

First, you'll need to "import" a cluster to your CDK app. To do that, use the
`eks.Cluster.fromClusterAttributes()` static method:

```ts
const cluster = eks.Cluster.fromClusterAttributes(this, 'MyCluster', {
  clusterName: 'my-cluster-name',
  kubectlRoleArn: 'arn:aws:iam::1111111:role/iam-role-that-has-masters-access',
});
```

Then, you can use `addManifest` or `addHelmChart` to define resources inside
your Kubernetes cluster. For example:

```ts
cluster.addManifest('Test', {
  apiVersion: 'v1',
  kind: 'ConfigMap',
  metadata: {
    name: 'myconfigmap',
  },
  data: {
    Key: 'value',
    Another: '123454',
  },
});
```

At the minimum, when importing clusters for `kubectl` management, you will need
to specify:

* `clusterName` - the name of the cluster.
* `kubectlRoleArn` - the ARN of an IAM role mapped to the `system:masters` RBAC
  role. If the cluster you are importing was created using the AWS CDK, the
  CloudFormation stack has an output that includes an IAM role that can be used.
  Otherwise, you can create an IAM role and map it to `system:masters` manually.
  The trust policy of this role should include the the
  `arn:aws::iam::${accountId}:root` principal in order to allow the execution
  role of the kubectl resource to assume it.

If the cluster is configured with private-only or private and restricted public
Kubernetes [endpoint access](#endpoint-access), you must also specify:

* `kubectlSecurityGroupId` - the ID of an EC2 security group that is allowed
  connections to the cluster's control security group. For example, the EKS managed [cluster security group](#cluster-security-group).
* `kubectlPrivateSubnetIds` - a list of private VPC subnets IDs that will be used
  to access the Kubernetes endpoint.

## Known Issues and Limitations

* [One cluster per stack](https://github.com/aws/aws-cdk/issues/10073)
* [Service Account dependencies](https://github.com/aws/aws-cdk/issues/9910)
* [Support isolated VPCs](https://github.com/aws/aws-cdk/issues/12171)
