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Version: v0.37 Stable
Supported Configurations
Running the control plane as a container with:

Integrating GCP Workload Identity with vCluster

This tutorial guides you through the process of integrating GCP Service Accounts with your vCluster using Workload Identity.

Setting up Workload Identity requires you to link a GCP Service Account with the Kubernetes Service Account (KSA) used by your workloads. This KSA needs to be available in the control plane cluster in which your vCluster instance runs.

To achieve this setup, we'll need to use the sync.toHost feature to expose the KSA in the control plane cluster together with the vCluster Platform API to retrieve the updated name of the KSA in the control plane cluster.

Prerequisites​

This guide assumes you have the following prerequisites:

  • kubectl installed
  • gcloud CLI installed and configured
  • A running GKE cluster with Workload Identity Federation enabled (GCP docs)

Step-by-Step Guide​

1. Start vCluster Platform and create access key​

In order to integrate your workloads with GKE Workload Identity, you'll need a vCluster Platform instance running. If you don't have one already, follow the vCluster Platform installation guide.

Once you're done, you'll need to create a new access key. This will allow you to use the vCluster Platform API. Please follow this guide to create a new access key.

2. Set Up Environment Variables​

Next, you need to set up the necessary environment variables. These variables include information about your GCP project, vCluster details, and authentication keys.

# Set up environment variables
export GSA_NAME=my-gke-sa
export VCLUSTER_KSA_NAME=demo-sa
export VCLUSTER_KSA_NAMESPACE=default
export GCP_PROJECT_ID=my-gcp-project-id-12345 # Replace with your actual GCP project ID
export VCLUSTER_NAME=my-vcluster
export HOST=https://my.loft.host  # Replace with your actual host
export ACCESS_KEY=abcd1234 # Replace with your actual vCluster Platform access key

Before proceeding adjust all values to your specific case, make sure to specify correct GCP project ID, vCluster Platform host and auth key.

3. Read Updated Name From vCluster Platform API​

vCluster rewrites the ServiceAccount name when it syncs the ServiceAccount to the control plane cluster. The synced name follows the pattern NAME-x-NAMESPACE-x-VCLUSTER_NAME. Cloud IAM trust policies must reference that synced name, not the name used inside the tenant cluster.

vCluster caps the rewritten name at 63 characters. This cap is vCluster's own, not a Kubernetes limit, since Kubernetes accepts ServiceAccount names up to 253 characters. When the rewritten name is longer, vCluster keeps its first 52 characters and appends - plus the first 10 characters of the hex-encoded SHA-256 digest of the full rewritten name. A trust policy built from the untruncated name doesn't match, and the failure surfaces as a permissions error rather than a naming error.

Resolve the name through the API

Don't hard-code synced ServiceAccount names or reimplement the truncation rule in your own automation. Query the vCluster Platform API as shown below so the name stays correct when namespace or tenant cluster names change.

This applies to ServiceAccounts that sync into the vCluster control plane's namespace, which is the default. If you enable namespace syncing and the ServiceAccount's namespace matches a mapping, vCluster keeps the name unchanged and the API returns a name that doesn't exist. In that case, reference the ServiceAccount by its original name in the mapped namespace on the control plane cluster.

Define a function to fetch the KSA name using curl and use it to export KSA_NAME environment variable.

# Define the function to get the KSA name using curl
get_ksa_name() {
  local vcluster_ksa_name=$1
  local vcluster_ksa_namespace=$2
  local vcluster_name=$3
  local host=$4
  local access_key=$5

  local resource_path="/kubernetes/management/apis/management.loft.sh/v1/translatevclusterresourcenames"
  local host_with_scheme=$([[ $host =~ ^(http|https):// ]] && echo "$host" || echo "https://$host")
  local sanitized_host="${host_with_scheme%/}"
  local full_url="${sanitized_host}${resource_path}"

  local response=$(curl -s -k -X POST "$full_url" \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer ${access_key}" \
    -d @- <<EOF
{
  "spec": {
    "name": "${vcluster_ksa_name}",
    "namespace": "${vcluster_ksa_namespace}",
    "vclusterName": "${vcluster_name}"
  }
}
EOF
  )

  local status_name=$(echo "$response" | jq -r '.status.name')
  if [[ -z "$status_name" || "$status_name" == "null" ]]; then
    echo "Error: Unable to fetch KSA name from response: $response"
    exit 1
  fi
  echo "$status_name"
}

# Get the KSA name
export KSA_NAME=$(get_ksa_name "$SERVICE_ACCOUNT_NAME" "$SERVICE_ACCOUNT_NAMESPACE" "$VCLUSTER_NAME" "$HOST" "$ACCESS_KEY")

4. Create vCluster Configuration​

Create vcluster.yaml file with following content:

sync:
  toHost:
    serviceAccounts:
      enabled: true

5. Deploy vCluster​

All of the deployment options below have the following assumptions:

  • A vcluster.yaml is provided. Refer to the vcluster.yaml reference docs to explore all configuration options. This file is optional and can be removed from the examples.
  • The vCluster is called my-vcluster.
  • The vCluster is be deployed into the team-x namespace.

The vCluster CLI provides the most straightforward way to deploy and manage virtual clusters.

  1. Install the vCluster CLI:

    brew install loft-sh/tap/vcluster

    The binaries in the tap are signed using the Sigstore framework for enhanced security.

    Verify the CLI installed successfully.

    vcluster --version

    Output is similar to:

    vCluster version 0.x.x

  2. Deploy vCluster:

    Modify the following with your specific values to generate a copyable command:
    vcluster create my-vcluster --namespace team-x --values vcluster.yaml
    note

    After installation, vCluster automatically switches your Kubernetes context to the new virtual cluster. You can now run kubectl commands against the virtual cluster.

6. Connect to vCluster​

Establish a connection to your vCluster instance:

vcluster connect ${VCLUSTER_NAME}

7. Create Example Workload​

Create a file named gcs-list-buckets-deployment.yaml with the following content:

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: demo-sa
  namespace: default
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gcs-list-buckets
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gcs-list-buckets
  template:
    metadata:
      labels:
        app: gcs-list-buckets
    spec:
      serviceAccountName: demo-sa
      containers:
      - image: google/cloud-sdk:slim
        command:
          - "gcloud"
          - "storage"
          - "buckets"
          - "list"
        name: gcs-pod

Apply the deployment:

kubectl apply -f gcs-list-buckets-deployment.yaml

9. Create a GCP Service Account​

Create a new GCP Service Account (SA) that will be used for workload identity.

# Create a new GCP Service Account
gcloud iam service-accounts create ${GSA_NAME} \
  --display-name "Workload Identity experiment SA"

10. Bind IAM Policies to the GCP Service Account​

Bind the necessary IAM policies to the GCP Service Account, allowing it to be used by the Kubernetes Service Account and to list GCS buckets.

Namespace configuration

The namespace parameter depends on your vCluster deployment type:

  • vCluster (not using the platform): Use the namespace where vCluster is deployed
  • Platform-managed vCluster: The namespace follows the pattern loft-<project-name>-v-<vcluster-name>

For vCluster deployments not connected with the platform (i.e. deployed with vcluster create or Helm without the platform):

# Set the namespace where vCluster is deployed
export VCLUSTER_NAMESPACE="team-x"  # Replace with your actual namespace

# Bind IAM policy for Workload Identity User
gcloud iam service-accounts add-iam-policy-binding ${GSA_NAME}@${GCP_PROJECT_ID}.iam.gserviceaccount.com \
  --member "serviceAccount:${GCP_PROJECT_ID}.svc.id.goog[${VCLUSTER_NAMESPACE}/${KSA_NAME}]" \
  --role "roles/iam.workloadIdentityUser"

# Bind IAM policy for Storage Object Viewer
gcloud projects add-iam-policy-binding ${GCP_PROJECT_ID} \
  --member "serviceAccount:${GSA_NAME}@${GCP_PROJECT_ID}.iam.gserviceaccount.com" \
  --role "roles/storage.objectViewer"

# Add IAM policy binding to the GCP project
gcloud projects add-iam-policy-binding ${GCP_PROJECT_ID} \
  --member "serviceAccount:${GSA_NAME}@${GCP_PROJECT_ID}.iam.gserviceaccount.com" \
  --role "roles/editor"

11. Annotate the Kubernetes Service Account​

Annotate the Kubernetes Service Account with the GCP Service Account email.

# Annotate the Kubernetes Service Account
kubectl annotate serviceaccount \
  --namespace ${VCLUSTER_KSA_NAMESPACE} \
  ${VCLUSTER_KSA_NAME} \
  iam.gke.io/gcp-service-account=${GSA_NAME}@${GCP_PROJECT_ID}.iam.gserviceaccount.com

12. Verify the Setup​

Verify that the setup is complete and the pod is able to list the GCS buckets using the IAM role.

kubectl logs -l app=gcs-list-buckets -n default

Following these steps will integrate your GCP Service Account with your vCluster, allowing you to manage resources securely and efficiently.