Attach your EKS cluster

Overview

To attach a cluster means to connect it to the Google Cloud by registering it with Google Cloud Fleet management and installing the GKE attached clusters software on it.

You can attach a cluster using the gcloud CLI or Terraform. To learn how to create and attach an EKS cluster using Terraform, check the GitHub repository of samples for GKE attached clusters.

To attach an EKS cluster using gcloud, perform the following steps.

Prerequisites

Ensure that your cluster meets the cluster requirements.

When attaching your cluster, you must specify:

a supported Google Cloud administrative region and
a platform version.

The administrative region is a Google Cloud region to administer your attached cluster from. You can choose any supported region, but best practice is to choose the region geographically closest to your cluster. No user data is stored in the administrative region.

The platform version is the version of GKE attached clusters to be installed on your cluster. You can list all supported versions by running the following command:

gcloud container attached get-server-config  \
  --location=GOOGLE_CLOUD_REGION

Replace GOOGLE_CLOUD_REGION with the name of the Google Cloud location to administer your cluster from.

Platform version numbering

These documents refer to the GKE attached clusters version as the platform version, to distinguish it from the Kubernetes version. GKE attached clusters uses the same version numbering convention as GKE - for example, 1.21.5-gke.1. When attaching or updating your cluster, you must choose a platform version whose minor version is the same as or one level below the Kubernetes version of your cluster. For example, you can attach a cluster running Kubernetes v1.22.* with GKE attached clusters platform version 1.21.* or 1.22.*.

This lets you upgrade your cluster to the next minor version before upgrading GKE attached clusters.

Attach an EKS cluster

To attach your EKS cluster to Google Cloud Fleet management, perform the following steps:

Ensure that your kubeconfig file has an entry for the cluster you'd like to attach:
```
aws eks update-kubeconfig --region AWS_REGION \
  --name CLUSTER_NAME
```
Retrieve the OIDC issuer URL with the following command:
```
aws eks describe-cluster \
  --region AWS_REGION \
  --name CLUSTER_NAME \
  --query "cluster.identity.oidc.issuer" \
  --output text
```
The output of this command is the URL of your OIDC issuer. Save this value for use later.
Run this command to extract your cluster's kubeconfig context and store it in the KUBECONFIG_CONTEXT environment variable:
```
KUBECONFIG_CONTEXT=$(kubectl config current-context)
```

Use the gcloud container attached clusters register command to register the cluster:

gcloud container attached clusters register CLUSTER_NAME \
  --location=GOOGLE_CLOUD_REGION \
  --fleet-project=PROJECT_NUMBER \
  --platform-version=PLATFORM_VERSION \
  --distribution=eks \
  --issuer-url=ISSUER_URL \
  --context=KUBECONFIG_CONTEXT \
  --kubeconfig=KUBECONFIG_PATH

Replace:

AWS_REGION: the AWS region where your EKS cluster is located
CLUSTER_NAME: the name of your cluster
GOOGLE_CLOUD_REGION: the Google Cloud region to administer your cluster
PLATFORM_VERSION: the GKE attached clusters version to use for the cluster
PROJECT_NUMBER: the fleet host project where the cluster will be registered
ISSUER_URL: the issuer URL retrieved earlier
KUBECONFIG_CONTEXT: context in the kubeconfig for accessing the EKS cluster, as extracted earlier
KUBECONFIG_PATH: path to your kubeconfig

Note: If attaching your cluster fails, the system automatically rolls back any changes made to Google Cloud resources related to the cluster, such as workload identity pool. This means the connection between your cluster and GKE attached clusters isn't established, but your actual EKS cluster remains unaffected. You can try again to attach the cluster after fixing the issue that caused the failure.

Authorize Cloud Logging / Cloud Monitoring

In order for GKE attached clusters to create and upload system logs and metrics to Google Cloud, it must be authorized.

To authorize the Kubernetes workload identity gke-system/gke-telemetry-agent to write logs to Google Cloud Logging, and metrics to Google Cloud Monitoring, run this command:

gcloud projects add-iam-policy-binding GOOGLE_PROJECT_ID \
  --member="serviceAccount:GOOGLE_PROJECT_ID.svc.id.goog[gke-system/gke-telemetry-agent]" \
  --role=roles/gkemulticloud.telemetryWriter

Replace GOOGLE_PROJECT_ID with the cluster's Google Cloud project ID.

This IAM binding grants access for all clusters in the Google Cloud project project to upload logs and metrics. You only need to run it after creating your first cluster for the project.

Adding this IAM binding will fail unless at least one cluster has been created in your Google Cloud project. This is because the workload identity pool it refers to (GOOGLE_PROJECT_ID.svc.id.goog) is not provisioned until cluster creation.